User Commands ksh93(1)
NAME
ksh93, rksh93 - Korn Shell, a standard and restricted com-
mand and programming language
SYNOPSIS
ksh93 []abcefhikmnoprstuvxBCD] [-R file] [ ]o option] ...
[-] [arg ...]
rksh93 []abcefhikmnoprstuvxBCD] [-R file] []o option] ...
[-] [arg ...]
DESCRIPTION
ksh93 is a command and programming language that executes
commands read from a terminal or a file. rksh93 is a res-
tricted version of the command interpreter ksh93. rksh93 is
used to set up login names and execution environments whose
capabilities are more controlled than those of the standard
shell.
See Invocation for the meaning of arguments to the shell.
Definitions
A metacharacter is defined as one of the following charac-
ters:
; & ( ) < > NEWLINE SPACE TAB
A blank is a TAB or a SPACE.
An identifier is a sequence of letters, digits, or under-
scores starting with a letter or underscore. Identifiers are
used as components of variable names.
A vname is a sequence of one or more identifiers separated
by a period (.) and optionally preceded by a period (.).
vnames are used as function and variable names.
A word is a sequence of characters from the character set
defined by the current locale, excluding non-quoted meta-
characters.
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A command is a sequence of characters in the syntax of the
shell language. The shell reads each command and carries out
the desired action either directly or by invoking separate
utilities. A built-in command is a command that is carried
out by the shell itself without creating a separate process.
Some commands are built-in purely for convenience and are
not documented in this manual page. Built-ins that cause
side effects in the shell environment and built-ins that are
found before performing a path search (see Execution) are
documented in this manual page. For historical reasons, some
of these built-ins behave differently than other built-ins
and are called special built-ins.
Commands
A simple-command is a list of variable assignments (see
Variable Assignments) or a sequence of blank-separated words
which can be preceded by a list of variable assignments. See
the Environment section of this manual page.
The first word specifies the name of the command to be exe-
cuted. Except as specified in this section, the remaining
words are passed as arguments to the invoked command. The
command name is passed as argument 0. See exec(2). The value
of a simple-command is its exit status. If it terminates
normally, its value is 0-255. If it terminates abnormally,
its value is 256]signum. The name of the signal correspond-
ing to the exit status can be obtained by way of the -l
option of the kill built-in utility.
A pipeline is a sequence of one or more commands separated
by . The standard output of each command but the last is
connected by a pipe(2) to the standard input of the next
command. Each command, except possibly the last, is run as a
separate process. The shell waits for the last command to
terminate. The exit status of a pipeline is the exit status
of the last command unless the pipefail option is enabled.
Each pipeline can be preceded by the reserved word!. This
causes the exit status of the pipeline to become 0 if the
exit status of the last command is non-zero, and 1 if the
exit status of the last command is 0.
A list is a sequence of one or more pipelines separated by
;, &, &, &&, or , and optionally terminated by ;, &, or
&. Of these five symbols, ;, &, and & have equal pre-
cedence, which is lower than that of && and . The symbols
&& and also have equal precedence.
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A semicolon (;) causes sequential execution of the preceding
pipeline. An ampersand (&) causes asynchronous execution of
the preceding pipeline, that is, the shell does not wait for
that pipeline to finish. The symbol & causes asynchronous
execution of the preceding pipeline with a two-way pipe
established to the parent shell. The standard input and out-
put of the spawned pipeline can be written to and read from
by the parent shell by applying the redirection operators <&
and >& with arg p to commands and by using -p option of the
built-in commands read and print. The symbol && () causes
the list following it to be executed only if the preceding
pipeline returns a zero (non-zero) value. One or more NEW-
LINEs can appear in a list instead of a semicolon, to del-
imit a command. The first item of the first pipeline of a
list that is a simple command not beginning with a redirec-
tion, and not occurring within a while, until, or if list ,
can be preceded by a semicolon. This semicolon is ignored
unless the showme option is enabled as described with the
set built-in.
A command is either a simple-command or one of commands in
the following list. Unless otherwise stated, the value
returned by a command is that of the last simple-command
executed in the command.
for vname [ in word ... ] ;do list ;done
Each time a for command is executed, vname is set to the
next word taken from the in word list. If in word ... is
omitted, the for command executes the do list once for
each positional parameter that is set starting from 1.
Execution ends when there are no more words in the list.
See Parameter Expansion.
(( [expr1] ; [expr2] ; [expr3] )) ;do list ;done
The arithmetic expression expr1 is evaluated first. The
arithmetic expression expr2 is repeatedly evaluated
until it evaluates to zero and when non-zero, list is
executed and the arithmetic expression expr3 evaluated.
If any expression is omitted, then it behaves as if it
evaluated to 1. See Arithmetic Evaluation.
select vname [ in word ... ] ;do list ;done
A select command prints on standard error (file descrip-
tor 2) the set of words, each preceded by a number. If
in word... is omitted, the positional parameters start-
ing from 1 are used instead. See Parameter Expansion.
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The PS3 prompt is printed and a line is read from the
standard input. If this line consists of the number of
one of the listed words, then the value of the variable
vname is set to the word corresponding to this number.
If this line is empty, the selection list is printed
again. Otherwise the value of the variable vname is set
to null. The contents of the line read from standard
input is saved in the variable REPLY. The list is exe-
cuted for each selection until a break or EOF is encoun-
tered. If the REPLY variable is set to null by the exe-
cution of list, the selection list is printed before
displaying the PS3 prompt for the next selection.
case word in [ [(] pattern [ pattern ] ... ) list ;; ] ...
esac
A case command executes the list associated with the
first pattern that matches word. The form of the pat-
terns is the same as that used for file name generation.
See File Name Generation.
The ;; operator causes execution of case to terminate.
If ;& is used in place of ;; the next subsequent list,
if any, is executed.
if list ;then list [ ;elif list ;then list ] ... [ ;else
list ] ;fi
The list following if is executed and, if it returns a
zero exit status, the list following the first then is
executed. Otherwise, the list following elif is exe-
cuted, and, if its value is zero, the list following the
next then is executed. Failing each successive elif
list, the else list is executed. If the if list has
non-zero exit status and there is no else list, then the
if command returns a zero exit status.
while list ;do list ;done
until list ;do list ;done
A while command repeatedly executes the while list and,
if the exit status of the last command in the list is
zero, executes the do list, otherwise the loop ter-
minates. If no commands in the do list are executed,
then the while command returns a zero exit status, until
can be used in place of while to negate the loop termi-
nation test.
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((expression))
The expression is evaluated using the rules for arith-
metic evaluation described in this manual page. If the
value of the arithmetic expression is non-zero, the exit
status is 0. Otherwise the exit status is 1.
(list;)
Execute list in a separate environment. If two adjacent
open parentheses are needed for nesting, a SPACE must be
inserted to avoid evaluation as an arithmetic command as
described in this section.
list is simply executed. Unlike the metacharacters, (
and ), { and } are reserved words and must occur at the
beginning of a line or after a ; to be recognized.
[ expression ]
Evaluates expression and returns a zero exit status when
expression is true. See Conditional Expressions for a
description of expression.
function varname { list ;}
varname () { list ;}
Define a function which is referenced by varname. A
function whose varname contains a . is called a discip-
line function and the portion of the varname preceding
the last . must refer to an existing variable.
The body of the function is the list of commands between
{ and }. A function defined with the function varname
syntax can also be used as an argument to the . special
built-in command to get the equivalent behavior as if
the varname() syntax were used to define it. See Func-
tions.
time [ pipeline ]
If pipeline is omitted, the user and system time for the
current shell and completed child processes is printed
on standard error. Otherwise, pipeline is executed and
the elapsed time as well as the user and system time are
printed on standard error. The TIMEFORMAT variable can
be set to a format string that specifies how the timing
information should be displayed. See Shell Variables for
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a description of the TIMEFORMAT variable.
The following reserved words are recognized as reserved only
when they are the first word of a command and are not
quoted:
case
do
done
else
elif
esac
for
fi
function
if
select
then
time
until
while
{ }
[ ]
!
Variable Assignments
One or more variable assignments can start a simple command
or can be arguments to the typeset, export, or readonly spe-
cial built-in commands. The syntax for an assignment is of
the form:
varname=word
varname[word]=word
No space is permitted between varname and the = or
between = and word.
varname=(assignlist)
No space is permitted between varname and the =. An
assignlist can be one of the following:
word ...
Indexed array assignment.
[word]=word ...
Associative array assignment. If prefixed by typeset
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-a, creates an indexed array instead.
assignment ...
Compound variable assignment. This creates a com-
pound variable varname with sub-variables of the
form varname.name, where name is the name portion of
assignment. The value of varname contains all the
assignment elements. Additional assignments made to
sub-variables of varname are also displayed as part
of the value of varname. If no assignments are
specified, varname is a compound variable allowing
subsequence child elements to be defined.
typeset [options] assignment ...
Nested variable assignment. Multiple assignments can
be specified by separating each of them with a ;.
The previous value is unset before the assignment.
In addition, a ]= can be used in place of the = to sig-
nify adding to or appending to the previous value. When
]= is applied to an arithmetic type, word is evaluated
as an arithmetic expression and added to the current
value. When applied to a string variable, the value
defined by word is appended to the value. For compound
assignments, the previous value is not unset and the new
values are appended to the current ones provided that
the types are compatible.
Comments
A word beginning with # causes that word and all the follow-
ing characters up to a NEWLINE to be commented, or ignored.
Aliasing
The first word of each command is replaced by the text of an
alias if an alias for this word has been defined. An alias
name consists of any number of characters excluding meta-
characters, quoting characters, file expansion characters,
parameter expansion characters, command substitution charac-
ters, and =. The replacement string can contain any valid
shell script including the metacharacters listed in the Com-
mands section. The first word of each command in the
replaced text, other than any that are in the process of
being replaced, are tested for aliases. If the last charac-
ter of the alias value is a BLANK then the word following
the alias is also checked for alias substitution.
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Aliases can be used to redefine built-in commands but cannot
be used to redefine the reserved words listed in the Com-
mands section. Aliases can be created and listed with the
alias command and can be removed with the unalias command.
Aliasing is performed when scripts are read, not while they
are executed. For an alias to take effect, the alias defini-
tion command has to be executed before the command which
references the alias is read. The following aliases are com-
piled into the shell but can be unset or redefined:
autoload='typeset -fu'
command='command '
fc=hist
float='typeset -lE'
functions='typeset -f'
hash='alias -t --'
history='hist -l'
integer='typeset -li'
nameref='typeset -n'
nohup='nohup '
r='hist -s'
redirect='command exec'
source='command .'
stop='kill -s STOP'
suspend='kill -s STOP $$'
times='{ { time;} 2>&1;}'
type='whence -v'
Tilde Substitution
After alias substitution is performed, each word is checked
to see if it begins with an unquoted tilde (~). For tilde
substitution, word also refers to the word portion of param-
eter expansion. See Parameter Expansion.
If it does, the word up to a / is checked to see if it
matches a user name in the password database. If a match is
found, the ~ and the matched login name are replaced by the
login directory of the matched user. If no match is found,
the original text is left unchanged. A ~ by itself, or in
front of a /, is replaced by $HOME. A ~ followed by a ] or -
is replaced by the value of $PWD and $OLDPWD respectively.
In addition, when expanding a variable assignment, tilde
substitution is attempted when the value of the assignment
begins with a ~, and when a ~ appears after a colon (:). The
: also terminates a ~ login name.
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Command Substitution
The standard output from a command enclosed in parentheses
preceded by a dollar sign ($) or a pair of grave accents
(``) can be used as part or all of a word. Trailing NEWLINEs
are removed. In the second (obsolete) form, the string
between the quotes is processed for special quoting charac-
ters before the command is executed. See Quoting.
The command substitution $(cat file) can be replaced by the
equivalent but faster $((list) runs
process list asynchronously connected to some file in
/dev/fd. The name of this file becomes the argument to the
command. If the form with > is selected then writing on this
file provides input for list. If < is used, then the file
passed as an argument contains the output of the list pro-
cess.
For example,
paste <(cut -f1 file1) <(cut -f3 file2) tee \
>(process1) >(process2)
cuts fields 1 and 3 from the files file1 and file2 respec-
tively, pastes the results together, and sends it to the
processes process1 and process2. It also displays the
results to the standard output. The file, which is passed as
an argument to the command, is a UNIX pipe(2). Programs that
expect to lseek(2) on the file do not work.
Parameter Expansion
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A parameter is a variable, one or more digits, or any of the
characters *, @, #, ?, -, $, and !. A variable is denoted by
a vname. To create a variable whose vname contains a ., a
variable whose vname consists of everything before the last
. must already exist. A variable has a value and zero or
more attributes. Variables can be assigned values and attri-
butes by using the typeset special built-in command. The
attributes supported by the shell are described later with
the typeset special built-in command. Exported variables
pass values and attributes to the environment.
The shell supports both indexed and associative arrays. An
element of an array variable is referenced by a subscript. A
subscript for an indexed array is denoted by an arithmetic
expression, (see Arithmetic Evaluation), between a [ and a
]. Use set -A vname value ... to assign values to an indexed
array. The value of all subscripts must be in the range of 0
through 1,048,575. Indexed arrays do not need to be
declared. Any reference to a variable with a valid subscript
is legal and an array is created if necessary.
An associative array is created with the -A option to
typeset. A subscript for an associative array is denoted by
a string enclosed between [ and ].
Referencing any array without a subscript is equivalent to
referencing the array with subscript 0.
The value of a variable can be assigned by:
vname=value [vname=value] ...
or
vname[subscript]=value [vname[subscript]=value] ...
No space is allowed before or after the =. A nameref is a
variable that is a reference to another variable. A nameref
is created with the -n attribute of typeset. The value of
the variable at the time of the typeset command becomes the
variable that is referenced whenever the nameref variable is
used. The name of a nameref cannot contain a dot (.). When a
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variable or function name contains a ., and the portion of
the name up to the first . matches the name of a nameref,
the variable referred to is obtained by replacing the nam-
eref portion with the name of the variable referenced by the
nameref. If a nameref is used as the index of a for loop, a
name reference is established for each item in the list. A
nameref provides a convenient way to refer to the variable
inside a function whose name is passed as an argument to a
function. For example, if the name of a variable is passed
as the first argument to a function, the command
typeset -n var=$1
inside the function causes references and assignments to var
to be references and assignments to the variable whose name
has been passed to the function. If either of the floating
point attributes, -E, or -F, or the integer attribute, -i,
is set for vname, then the value is subject to arithmetic
evaluation as described in this manual page. Positional
parameters, parameters denoted by a number, can be assigned
values with the set special built-in command. Parameter $0
is set from argument zero when the shell is invoked. The
character $ is used to introduce substitutable parameters.
${parameter}
The shell reads all the characters from ${ to the match-
ing } as part of the same word even if it contains
braces or metacharacters. The value, if any, of the
parameter is substituted. The braces are required when
parameter is followed by a letter, digit, or underscore
that is not to be interpreted as part of its name, when
the variable name contains a ., or when a variable is
subscripted. If parameter is one or more digits then it
is a positional parameter. A positional parameter of
more than one digit must be enclosed in braces. If
parameter is * or @, then all the positional parameters,
starting with $1, are substituted and separated by a
field separator character. If an array vname with sub-
script * or @ is used, then the value for each of the
elements is substituted, separated by the first charac-
ter of the value of IFS.
${#parameter}
If parameter is * or @, the number of positional parame-
ters is substituted. Otherwise, the length of the value
of the parameter is substituted.
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${#vname[*]}
${#vname[@]}
The number of elements in the array vname is substi-
tuted.
${!vname}
Expands to the name of the variable referred to by
vname. This is vname except when vname is a name refer-
ence.
${!vname[subscript]}
Expands to name of the subscript unless subscript is *
or @. When subscript is *, the list of array subscripts
for vname is generated. For a variable that is not an
array, the value is 0 if the variable is set. Otherwise
it is null. When subscript is @, it is the same as $
{vname[*]}, except that when used in double quotes, each
array subscript yields a separate argument.
${!prefix*}
Expands to the names of the variables whose names begin
with prefix.
${parameter:-word}
If parameter is set and is non-null then substitute its
value. Otherwise substitute word.
word is not evaluated unless it is to be used as the
substituted string.
In the following example, pwd is executed only if d is
not set or is NUL:
print ${d:-$(pwd)}
If the colon (: ) is omitted from the expression, the
shell only checks whether parameter is set or not.
${parameter:=word}
If parameter is not set or is null, set it to word. The
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value of the parameter is then substituted. Positional
parameters cannot be assigned to in this way.
word is not evaluated unless it is to be used as the
substituted string.
In the following example, pwd is executed only if d is
not set or is NUL:
print ${d:-$(pwd)}
If the colon (:) is omitted from the expression, the
shell only checks whether parameter is set or not.
${parameter:?word}
If parameter is set and is non-null, substitute its
value. Otherwise, print word and exit from the shell ,
if the shell is not interactive. If word is omitted then
a standard message is printed.
word is not evaluated unless it is to be used as the
substituted string.
In the following example, pwd is executed only if d is
not set or is NUL:
print ${d:-$(pwd)}
If the colon (: ) is omitted from the expression, the
shell only checks whether parameter is set or not.
${parameter:]word}
If parameter is set and is non-null, substitute word.
Otherwise substitute nothing.
word is not evaluated unless it is to be used as the
substituted string.
In the following example, pwd is executed only if d is
not set or is NUL:
print ${d:-$(pwd)}
If the colon (:) is omitted from the expression, the
shell only checks whether parameter is set or not.
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${parameter:offset:length}
${parameter:offset}
Expands to the portion of the value of parameter start-
ing at the character (counting from 0) determined by
expanding offset as an arithmetic expression and con-
sisting of the number of characters determined by the
arithmetic expression defined by length.
In the second form, the remainder of the value is used.
A negative offset counts backwards from the end of
parameter.
One or more BLANKs is required in front of a minus sign
to prevent the shell from interpreting the operator as
:-. If parameter is * or @, or is an array name indexed
by * or @, then offset and length refer to the array
index and number of elements respectively. A negative
offset is taken relative to one greater than the highest
subscript for indexed arrays. The order for associative
arrays is unspecified.
${parameter#pattern}
${parameter##pattern}
If the shell pattern matches the beginning of the value
of parameter, then the value of this expansion is the
value of the parameter with the matched portion deleted.
Otherwise the value of this parameter is substituted. In
the first form the smallest matching pattern is deleted
and in the second form the largest matching pattern is
deleted. When parameter is @, *, or an array variable
with subscript @ or *, the substring operation is
applied to each element in turn.
${parameter%pattern}
${parameter%%pattern}
If the shell pattern matches the end of the value of
parameter, then the value of this expansion is the value
of the parameter with the matched part deleted. Other-
wise substitute the value of parameter. In the first
form the smallest matching pattern is deleted, and in
the second form the largest matching pattern is deleted.
When parameter is @, *, or an array variable with sub-
script @ or *, the substring operation is applied to
each element in turn.
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${parameter/pattern/string}
${parameter/pattern/string}
${parameter/#pattern/string}
${parameter/%pattern/string}
Expands parameter and replaces the longest match of pat-
tern with the specified string. Each occurrence of \n in
string is replaced by the portion of parameter that
matches the nth sub-pattern.
When string is null, the pattern is deleted and the / in
front of string can be omitted. When parameter is @, *,
or an array variable with subscript @ or *, the substi-
tution operation is applied to each element in turn. In
this case, the string portion of word is re-evaluated
for each element.
In the first form, only the first occurrence of pattern
is replaced.
In the second form, each match for pattern is replaced
by the specified string.
The third form restricts the pattern match to the begin-
ning of the string.
The fourth form restricts the pattern match to the end
of the string.
The following parameters are automatically set by the shell:
# The number of positional parameters in
decimal.
- Options supplied to the shell on invoca-
tion or by the set command.
? The decimal value returned by the last
executed command.
$ The process number of this shell.
Initially, the value of is the absolute
pathname of the shell or script being
executed as passed in the environment. It
is subsequently assigned the last
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argument of the previous command.
This parameter is not set for commands
which are asynchronous. This parameter is
also used to hold the name of the match-
ing MAIL file when checking for mail.
! The process number of the last background
command invoked or the most recent job
put in the background with the bg built-
in command.
.sh.command When processing a DEBUG trap, this vari-
able contains the current command line
that is about to run.
.sh.edchar This variable contains the value of the
keyboard character (or sequence of char-
acters if the first character is an ESC,
ASCI 033) that has been entered when
processing a KEYBD trap. If the value is
changed as part of the trap action, then
the new value replaces the key (or key
sequence) that caused the trap. See the
Key Bindings section of this manual page.
.sh.edcol The character position of the cursor at
the time of the most recent KEYBD trap.
.sh.edmode The value is set to ESC when processing a
KEYBD trap while in vi insert mode. Oth-
erwise, .sh.edmode is null when process-
ing a KEYBD trap. See the vi Editing Mode
section of this manual page.
.sh.edtext The characters in the input buffer at the
time of the most recent KEYBD trap. The
value is null when not processing a KEYBD
trap.
.sh.file The pathname of the file than contains
the current command.
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.sh.fun The name of the current function that is
being executed.
.sh.match An indexed array which stores the most
recent match and sub-pattern matches
after conditional pattern matches that
match and after variables expansions
using the operators #, %, or /. The 0th
element stores the complete match and the
ith element stores the ith sub-match. The
.sh.match variable is unset when the
variable that has expanded is assigned a
new value.
.sh.name Set to the name of the variable at the
time that a discipline function is
invoked.
.sh.subscript Set to the name subscript of the variable
at the time that a discipline function is
invoked.
.sh.subshell The current depth for sub-shells and com-
mand substitution.
.sh.value Set to the value of the variable at the
time that the set or append discipline
function is invoked.
.sh.version Set to a value that identifies the ver-
sion of this shell.
LINENO The current line number within the script
or function being executed.
OLDPWD The previous working directory set by the
cd command.
OPTARG The value of the last option argument
processed by the getopts built-in com-
mand.
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OPTIND The index of the last option argument
processed by the getopts built-in com-
mand.
PID The process number of the parent of the
shell.
PWD The present working directory set by the
cd command.
RANDOM Each time this variable is referenced, a
random integer, uniformly distributed
between 0 and 32767, is generated. The
sequence of random numbers can be ini-
tialized by assigning a numeric value to
RANDOM.
REPLY This variable is set by the select state-
ment and by the read built-in command
when no arguments are supplied.
SECONDS Each time this variable is referenced,
the number of seconds since shell invoca-
tion is returned. If this variable is
assigned a value, then the value returned
upon reference is the value that was
assigned plus the number of seconds since
the assignment.
The following variables are used by the shell:
CDPATH Defines the search path for the cd command.
COLUMNS Defines the width of the edit window for the
shell edit modes and for printing select
lists.
EDITOR If the VISUAL variable is not set, the value
of this variable is checked for the patterns
as described with VISUAL and the corresponding
editing option is turned on.
See the set command in the Special Command
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section of this manual page.
ENV Performs parameter expansion, command substi-
tution, and arithmetic substitution on the
value to generate the pathname of the script
that is executed when the shell is invoked.
This file is typically used for alias and
function definitions. The default value is
$HOME/.kshrc.
See the Invocation section of this manual
page.
ENV is not set by the shell.
FCEDIT Obsolete name for the default editor name for
the hist command. FCEDIT is not used when
HISTEDIT is set.
The shell specifies a default value to FCEDIT.
FIGNORE A pattern that defines the set of file names
that is ignored when performing file name
matching.
FPATH The search path for function definitions. The
directories in this path are searched for a
file with the same name as the function or
command when a function with the -u attribute
is referenced and when a command is not found.
If an executable file with the name of that
command is found, then it is read and executed
in the current environment. Unlike PATH, the
current directory must be represented expli-
citly by dot (.) rather than by adjacent colon
(:) characters or a beginning or ending colon
(:).
HISTCMD The number of the current command in the his-
tory file.
HISTEDIT The name for the default editor name for the
hist command.
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HISTFILE If this variable is set when the shell is
invoked, the value is the pathname of the file
that is used to store the command history. See
the Command Re-entry section of this manual
page.
HISTSIZE If this variable is set when the shell is
invoked, then the number of previously entered
commands that are accessible by this shell is
greater than or equal to this number. The
default is 512.
HOME The default argument (home directory) for the
cd command.
HOME is not set by the shell. HOME is set by
login(1).
IFS Internal field separators, normally SPACE,
TAB, and NEWLINE that are used to separate the
results of command substitution or parameter
expansion and to separate fields with the
built-in command read. The first character of
the IFS variable is used to separate arguments
for the "$*" substitution. See the Quoting
section of this manual page.
Each single occurrence of an IFS character in
the string to be split, that is not in the
issspace character class, and any adjacent
characters in IFS that are in the issspace
character class, delimit a field. One or more
characters in IFS that belong to the issspace
character class, delimit a field. In addition,
if the same issspace character appears con-
secutively inside IFS, this character is
treated as if it were not in the issspace
class, so that if IFS consists of two tab
characters, then two adjacent tab characters
delimit a null field.
The shell specifies a default value to IFS.
LANG This variable determines the locale category
for any category not specifically selected
with a variable starting with LC or LANG.
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LCAL This variable overrides the value of the LANG
variable and any other LC variable.
LCOLATE This variable determines the locale category
for character collation information.
LCTYPE This variable determines the locale category
for character handling functions. It deter-
mines the character classes for pattern match-
ing. See the File Name Generation section of
this manual page.
LCNUMERIC This variable determines the locale category
for the decimal point character.
LINES If this variable is set, the value is used to
determine the column length for printing
select lists. Select lists prints vertically
until about two-thirds of LINES lines are
filled.
MAIL If this variable is set to the name of a mail
file and the MAILPATH variable is not set,
then the shell informs the user of arrival of
mail in the specified file.
MAIL is not set by the shell. On some systems,
MAIL is set by login(1).
MAILCHECK Specifies how often in seconds the shell
checks for changes in the modification time of
any of the files specified by the MAILPATH or
MAIL variables. The default value is 600
seconds. When the time has elapsed the shell
checks before issuing the next prompt.
The shell specifies a default value to MAIL-
CHECK.
MAILPATH A colon ( : ) separated list of file names. If
this variable is set, then the shell informs
the user of any modifications to the specified
files that have occurred within the last MAIL-
CHECK seconds. Each file name can be followed
by a ? and a message that is printed. The
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message undergoes parameter expansion, command
substitution, and arithmetic substitution with
the variable $ defined as the name of the
file that has changed. The default message is
you have mail in $.
PATH The search path for commands. Except in .pro-
file, users cannot change PATH if executing
under rksh93. See the Execution section of
this manual page.
The shell specifies a default value to PATH.
PS1 The value of this variable is expanded for
parameter expansion, command substitution, and
arithmetic substitution to define the primary
prompt string which by default is $. The char-
acter ! in the primary prompt string is
replaced by the command number. Two successive
occurrences of ! produces a single ! when the
prompt string is printed. See the Command Re-
entry section of this manual page.
The shell specifies a default value to PS1.
PS2 Secondary prompt string, by default, >.
The shell specifies a default value to PS2.
PS3 Selection prompt string used within a select
loop, by default #?.
The shell specifies a default value to PS3.
PS4 The value of this variable is expanded for
parameter evaluation, command substitution,
and arithmetic substitution and precedes each
line of an execution trace. By default, PS4 is
]. When PS4 is unset, the execution trace
prompt is also ] .
The shell specifies a default value to PS4.
SHEL The pathname of the shell is kept in the
environment. At invocation, if the basename of
this variable is rsh, rksh, rksh93, or krsh,
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the shell becomes restricted.
SHEL is not set by the shell. On some sys-
tems, SHEL is set by login(1).
TIMEFORMAT The value of this parameter is used as a for-
mat string specifying how the timing informa-
tion for pipelines prefixed with the time
reserved word should be displayed. The % char-
acter introduces a format sequence that is
expanded to a time value or other information.
The format sequences and their meanings are as
follows.
%%
A literal %.
%[p][l]R
The elapsed time in seconds.
%[p][l]U
The number of CPU seconds spent in user
mode.
%[p][l]S
The number of CPU seconds spent in system
mode.
%P
The CPU percentage, computed as (U ] S) /
R.
The braces denote optional portions. The
optional p is a digit specifying the preci-
sion, the number of fractional digits after a
decimal point. A value of 0 causes no decimal
point or fraction to be output. At most three
places after the decimal point can be
displayed. Values of p greater than 3 are
treated as 3. If p is not specified, the value
3 is used.
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The optional l specifies a longer format,
including hours if greater than zero, minutes,
and seconds of the form HhMmS.Fs. The
value of p determines whether or not the frac-
tion is included.
All other characters are output without change
and a trailing NEWLINE is added. If unset, the
default value, $'0eal%2lR0ser%2lU0ys%2lS', is
used. If the value is null, no timing informa-
tion is displayed.
TMOUT If set to a value greater than zero, TMOUT is
the default time-out value for the read
built-in command. The select compound command
terminates after TMOUT seconds when input is
from a terminal. Otherwise, the shell ter-
minates if a line is not entered within the
prescribed number of seconds while reading
from a terminal. The shell can be compiled
with a maximum bound for this value which can-
not be exceeded.
The shell specifies a default value to TMOUT.
VISUAL If the value of this variable matches the pat-
tern *[Vv][Ii]*, then the vi option is turned
on. See Special Commands. If the value matches
the pattern *gmacs* , the gmacs option is
turned on. If the value matches the pattern
*macs*, then the emacs option is turned on.
The value of VISUAL overrides the value of
EDITOR.
Field Splitting
After parameter expansion and command substitution, the
results of substitutions are scanned for the field separator
characters (those found in IFS) and split into distinct
fields where such characters are found. Explicit null fields
("" or '') are retained. Implicit null fields, those result-
ing from parameters that have no values or command substitu-
tions with no output, are removed.
If the braceexpand (-B) option is set, each of the fields
resulting from IFS are checked to see if they contain one or
more of the brace patterns. Valid brace patterns: {*,*},
{l1..l2} , {n1..n2}, {n1..n2%fmt} {n1..n2 ..n3}, or {n1..n2
..n3%fmt} , where * represents any character, l1,l2 are
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letters and n1,n2,n3 are signed numbers and fmt is a format
specified as used by printf. In each case, fields are
created by prepending the characters before the { and
appending the characters after the } to each of the strings
generated by the characters between the { and }. The result-
ing fields are checked to see if they have any brace pat-
terns.
In the first form, a field is created for each string
between { and ,, between , and ,, and between , and }. The
string represented by * can contain embedded matching { and
} without quoting. Otherwise, each { and } with * must be
quoted.
In the second form, l1 and l2 must both be either upper case
or both be lower case characters in the C locale. In this
case a field is created for each character from l1 through
l2.
In the remaining forms, a field is created for each number
starting at n1. This continues until it reaches n2 and
increments n1 by n3. The cases where n3 is not specified
behave as if n3 were 1 if n1<=n2, and -1 otherwise. In forms
which specify %fmt, any format flags, widths and precisions
can be specified and fmt can end in any of the specifiers
cdiouxX. For example, {a,z}{1..5..3%02d}{b..c}x expands to
the 8 fields, a01bx, a01cx, a04bx, a04cx, z01bx, z01cx,
z04bx, and z4cx.
File Name Generation
Following splitting, each field is scanned for the charac-
ters *, ?, (, and [, unless the -f option has been set. If
one of these characters appears, then the word is regarded
as a pattern.
Each file name component that contains any pattern character
is replaced with a lexicographically sorted set of names
that matches the pattern from that directory. If no file
name is found that matches the pattern, then that component
of the file name is left unchanged unless the pattern is
prefixed with ~(N) in which case it is removed. If FIGNORE
is set, then each file name component that matches the pat-
tern defined by the value of FIGNORE is ignored when gen-
erating the matching file names. The names . and .. are also
ignored. If FIGNORE is not set, the character . at the start
of each file name component is ignored unless the first
character of the pattern corresponding to this component is
the character . itself. For other uses of pattern matching
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the / and . are not specially treated.
* Match any string, including the null string. When
used for file name expansion, if the globstar
option is on, two adjacent *s by themselves match
all files and zero or more directories and sub-
directories. If the two adjacent *s are followed
by a /, only directories and subdirectories
match.
? Matches any single character.
[...] Match any one of the enclosed characters. A pair
of characters separated by - matches any charac-
ter lexically between the pair, inclusive. If the
first character following the opening [ is a !,
any character not enclosed is matched. A - can be
included in the character set by putting it as
the first or last character. Within [ and ],
character classes can be specified with the syn-
tax [:class:] where class is one of the following
classes defined in the ANSI-C standard:
alnum alpha blank cntrl digit graph
lower print punct space upper
word xdigit
word is equivalent to alnum plus the character .
Within [ and ], an equivalence class can be
specified with the syntax [=c=] which matches all
characters with the same primary collation weight
(as defined by the current locale) as the charac-
ter c. Within [ and ], [.symbol.] matches the
collating symbol symbol.
A pattern-list is a list of one or more patterns separated
from each other with an & or . An & signifies that all pat-
terns must be matched whereas requires that only one pat-
tern be matched. Composite patterns can be formed with one
or more of the following sub-patterns:
?(pattern-list) Optionally matches any one of the
specified patterns.
*(pattern-list) Matches zero or more occurrences of
the specified patterns.
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](pattern-list) Matches one or more occurrences of the
specified patterns.
{n(pattern-list) Matches n occurrences of the specified
patterns.
{m,n(pattern-list) Matches from m to n occurrences of the
specified patterns. If m is omitted, 0
is used. If n is omitted at least m
occurrences are matched.
@(pattern-list) Matches exactly one of the specified
patterns.
!(pattern-list) Matches anything except one of the
specified patterns.
By default, each pattern, or sub-pattern matches the longest
string possible consistent with generating the longest
overall match. If more than one match is possible, the one
starting closest to the beginning of the string is chosen.
However, for each of the compound patterns a - can be
inserted in front of the ( to cause the shortest match to
the specified pattern-list to be used.
When pattern-list is contained within parentheses, the
backslash character \ is treated specially even when inside
a character class. All ANSI-C character escapes are recog-
nized and match the specified character. In addition the
following escape sequences are recognized:
\d Matches any character in the digit class.
\D Matches any character not in the digit class.
\s Matches any character in the space class.
\S Matches any character not in the space class.
\w Matches any character in the word class.
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\W Matches any character not in the word class.
A pattern of the form %(pattern-pairs) is a sub-pattern that
can be used to match nested character expressions. Each
pattern-pair is a two character sequence which cannot con-
tain & or . The first pattern-pair specifies the starting
and ending characters for the match. Each subsequent
pattern-pair represents the beginning and ending characters
of a nested group that is skipped over when counting start-
ing and ending character matches. The behavior is unspeci-
fied when the first character of a pattern-pair is
alphanumeric except for the following:
D Causes the ending character to terminate the search for
this pattern without finding a match.
E Causes the ending character to be interpreted as an
escape character.
L Causes the ending character to be interpreted as a
quote character causing all characters to be ignored
when looking for a match.
Q Causes the ending character to be interpreted as a
quote character causing all characters other than any
escape character to be ignored when looking for a
match.
%({}Q"E\), matches characters starting at { until the match-
ing } is found not counting any { or } that is inside a dou-
ble quoted string or preceded by the escape character \.
Without the {} this pattern matches any C language string.
Each sub-pattern in a composite pattern is numbered, start-
ing at 1, by the location of the ( within the pattern. The
sequence \n, where n is a single digit and \n comes after
the nth. sub-pattern, matches the same string as the sub-
pattern itself.
A pattern can contain sub-patterns of the form
~(options:pattern-list), where either options or :pattern-
list can be omitted. Unlike the other compound patterns,
these sub-patterns are not counted in the numbered sub-
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patterns. If options is present, it can consist of one or
more of the following:
] Enable the following options. This is the default.
- Disable the following options.
E The remainder of the pattern uses extended regular
expression syntax like the egrep(1) command.
F The remainder of the pattern uses fgrep(1) expression
syntax.
g File the longest match (greedy).
This is the default.
G The remainder of the pattern uses basic regular expres-
sion syntax like the grep(1) command.
i Treat the match as case insensitive.
K The remainder of the pattern uses shell pattern syntax.
This is the default.
l Left anchor the pattern.
This is the default for K style patterns.
N This is ignored. However, when it is the first letter
and is used with file name generation, and no matches
occur, the file pattern expands to the empty string.
r Right anchor the pattern.
This is the default for K style patterns.
If both options and :pattern-list are specified, then the
options apply only to pattern-list. Otherwise, these options
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remain in effect until they are disabled by a subsequent
~(...) or at the end of the sub-pattern containing ~(...).
Quoting
Each of the metacharacters listed in the Definitions has a
special meaning to the shell.
g File the longest match (greedy). This is the default.
i Treat the match as case insensitive.
If both options and :pattern-list are specified, then the
options apply only to pattern-list. Otherwise, the options
remain in effect until they are disabled by a subsequent
~(...) or at the end of the sub-pattern containing ~(...).
Each of the metacharacters listed in the Definitions section
of this manual page has a special meaning to the shell and
causes termination of a word unless quoted. A character can
be quoted, that is, made to stand for itself, by preceding
it with a backslash (\). The pair \NEWLINE is removed. All
characters enclosed between a pair of single quote marks
('') that is not preceded by a $ are quoted. A single quote
cannot appear within the single quotes. A single quoted
string preceded by an unquoted $ is processed as an ANSI-C
string except for the following:
\0 Causes the remainder of the string to be
ignored.
\cx Expands to the character CTRL-x.
\C[.name.] Expands to the collating element name.
\e Equivalent to the escape character (ASCI
033),
\E Equivalent to the escape character (ASCI
033),
Inside double quote marks (""), parameter and command sub-
stitution occur and \ quotes the characters \, `, ", and $.
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A $ in front of a double quoted string is ignored in the C
or POSIX locale, and might cause the string to be replaced
by a locale specific string otherwise. The meaning of $* and
$@ is identical when not quoted or when used as a variable
assignment value or as a file name. However, when used as a
command argument, "$*" is equivalent to "$1d$2d...", where d
is the first character of the IFS variable, whereas "$@" is
equivalent to "$1" "$2" .... Inside grave quote marks (``),
\fR quotes the characters \, `, and $. If the grave quotes
occur within double quotes, then \ also quotes the character
".
The special meaning of reserved words or aliases can be
removed by quoting any character of the reserved word. The
recognition of function names or built-in command names can-
not be altered by quoting them.
Arithmetic Evaluation
The shell performs arithmetic evaluation for arithmetic sub-
stitution, to evaluate an arithmetic command, to evaluate an
indexed array subscript, and to evaluate arguments to the
built-in commands shift and let. Arithmetic evaluation is
also performed on argument operands of the built-in command
printf that correspond to numeric format specifiers in the
format operand. See printf(1). Evaluations are performed
using double precision floating point arithmetic or long
double precision floating point for systems that provide
this data type. Floating point constants follow the ANSI-C
programming language floating point conventions. Integer
constants follow the ANSI-C programming language integer
constant conventions although only single byte character
constants are recognized and character casts are not recog-
nized. Constants can be of the form [base#]n where base is a
decimal number between two and sixty-four representing the
arithmetic base and n is a number in that base. The digits
greater than 9 are represented by the lower case letters,
the upper case letters, @, and respectively. For bases
less than or equal to 36, upper and lower case characters
can be used interchangeably.
An arithmetic expression uses the same syntax, precedence,
and associativity of expression as the C language. All the C
language operators that apply to floating point quantities
can be used. In addition, the operator ** can be used for
exponentiation. It has higher precedence than multiplication
and is left associative. When the value of an arithmetic
variable or subexpression can be represented as a long
integer, all C language integer arithmetic operations can be
performed. Variables can be referenced by name within an
arithmetic expression without using the parameter expansion
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syntax. When a variable is referenced, its value is
evaluated as an arithmetic expression.
Any of the following math library functions that are in the
C math library can be used within an arithmetic expression:
abs acos acosh asin asinh atan atan2 atanh cbrt
copysign cos cosh erf erfc exp exp2 expm1 fabs
fdim finite floor fma fmax fmod hypot ilogb
int isinf isnan lgamma log log2 logb
nearbyint nextafter nexttoward pow remainder
rint round sin sinh sqrt tan tanh tgamma trunc
An internal representation of a variable as a double preci-
sion floating point can be specified with the -E [n] or -F
[n] option of the typeset special built-in command. The -E
option causes the expansion of the value to be represented
using scientific notation when it is expanded. The optional
option argument n defines the number of significant figures.
The -F option causes the expansion to be represented as a
floating decimal number when it is expanded. The optional
option argument n defines the number of places after the
decimal point in this case.
An internal integer representation of a variable can be
specified with the -i [n] option of the typeset special
built-in command. The optional option argument n specifies
an arithmetic base to be used when expanding the variable.
If you do not specify an arithmetic base, base 10 is used.
Arithmetic evaluation is performed on the value of each
assignment to a variable with the -E, -F, or -i option.
Assigning a floating point number to a variable whose type
is an integer causes the fractional part to be truncated.
Prompting
When used interactively, the shell prompts with the value of
PS1 after expanding it for parameter expansion, command sub-
stitution, and arithmetic substitution, before reading a
command. In addition, each single ! in the prompt is
replaced by the command number. A !! is required to place !
in the prompt. If at any time a NEWLINE is typed and further
input is needed to complete a command, then the secondary
prompt, that is, the value of PS2, is issued.
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Conditional Expressions
A conditional expression is used with the [ compound com-
mand to test attributes of files and to compare strings.
Field splitting and file name generation are not performed
on the words between [ and ].
Each expression can be constructed from one or more of the
following unary or binary expressions:
-a file True, if file exists.
This option is the same as -e. This
option is obsolete.
-b file True, if file exists and is a block
special file.
-c file True, if file exists and is a character
special file.
-d file True, if file exists and is a direc-
tory.
-e file True, if file exists.
-f file True, if file exists and is an ordinary
file.
-g file True, if file exists and it has its
setgid bit set.
-G file True, if file exists and its group
matches the effective group id of this
process.
-h file True, if file exists and is a symbolic
link.
-k file True, if file exists and it has its
sticky bit set.
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-L file True, if file exists and is a symbolic
link.
-n string True, if length of string is non-zero.
-N file True, if file exists and the modifica-
tion time is greater than the last
access time.
-o option True, if option named option is on.
-o ?option True, if option named option is a valid
option name.
-O file True, if file exists and is owned by
the effective user id of this process.
-p file True, if file exists and is a FIFO spe-
cial file or a pipe.
-r file True, if file exists and is readable by
current process.
-s file True, if file exists and has size
greater than zero.
-S file True, if file exists and is a socket.
-t fildes True, if file descriptor number fildes
is open and associated with a terminal
device.
-u file True, if file exists and it has its
setuid bit set.
-w file True, if file exists and is writable by
current process.
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-x file True, if file exists and is executable
by current process. If file exists and
is a directory, then true if the
current process has permission to
search in the directory.
-z string True, if length of string is zero.
file1 -ef file2 True, if file1 and file2 exist and
refer to the same file.
file1 -nt file2 True, if file1 exists and file2 does
not, or file1 is newer than file2.
file1 -ot file2 True, if file2 exists and file1 does
not, or file1 is older than file2.
string True, if string is not null.
string == pattern True, if string matches pattern. Any
part of pattern can be quoted to cause
it to be matched as a string. With a
successful match to pattern, the
.sh.match array variable contains the
match and sub-pattern matches.
string = pattern Same as ==, but is obsolete.
string != pattern True, if string does not match pattern.
When the string matches the pattern the
.sh.match array variable contains the
match and sub-pattern matches.
string =~ ere True if string matches the pattern
~(E)ere where ere is an extended regu-
lar expression.
string1 < string2 True, if string1 comes before string2
based on ASCI value of their charac-
ters.
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string1 > string2 True, if string1 comes after string2
based on ASCI value of their charac-
ters.
In each of the following expressions, if file is of the form
/dev/fd/n, where n is an integer, the test is applied to the
open file whose descriptor number is n. The following
obsolete arithmetic comparisons are supported:
exp1 -eq exp2 True, if exp1 is equal to exp2.
exp1 -ge exp2 True, if exp1 is greater than or equal to
exp2.
exp1 -gt exp2 True, if exp1 is greater than exp2.
exp1 -le exp2 True, if exp1 is less than or equal to
exp2.
exp1 -lt exp2 True, if exp1 is less than exp2.
exp1 -ne exp2 True, if exp1 is not equal to exp2.
A compound expression can be constructed from these primi-
tives by using any of the following, listed in decreasing
order of precedence:
(expression) True, if expression is true.
Used to group expressions.
! expression True, if expression is false.
expression1 && expression2 True, if expression1 and
expression2 are both true.
expression1 expression2 True, if either expression1 or
expression2 is true.
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Input and Output
Before a command is executed, its input and output can be
redirected using a special notation interpreted by the
shell. The following can appear anywhere in a simple command
or can precede or follow a command and are not passed on to
the invoked command. Command substitution, parameter expan-
sion, and arithmetic substitution occur before word or digit
is used except as noted in this section. File name genera-
tion occurs only if the shell is interactive and the pattern
matches a single file. Field splitting is not performed.
In each of the following redirections, if file is of the
form /dev/sctp/host/port, /dev/tcp/host/port, or
/dev/udp/host/port, where host is a hostname or host
address, and port is a service specified by name or an
integer port number, then the redirection attempts to make a
tcp, sctp or udp connection to the corresponding socket.
No intervening space is allowed between the characters of
redirection operators.
word Use file word as standard output (file
descriptor 1). If the file does not exist then
it is created. If the file exists, and the
noclobber option is on, this causes an error.
Otherwise, it is truncated to zero length.
>word Same as >, except that it overrides the
noclobber option.
>>word Use file word as standard output. If the file
exists, then output is appended to it (by
first seeking to the end-of-file). Otherwise,
the file is created.
<>word Open file word for reading and writing as
standard input.
<<[-]word The shell input is read up to a line that is
the same as word after any quoting has been
removed, or to an end-of-file. No parameter
substitution, command substitution, arithmetic
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User Commands ksh93(1)
substitution or file name generation is per-
formed on word. The resulting document, called
a here-document, becomes the standard input.
If any character of word is quoted, then no
interpretation is placed upon the characters
of the document. Otherwise, parameter expan-
sion, command substitution, and arithmetic
substitution occur, \NEWLINE is ignored, and \
must be used to quote the characters \, $, `.
If - is appended to <<, then all leading tabs
are stripped from word and from the document.
If # is appended to <<, then leading SPACEs
and TABs are stripped off the first line of
the document and up to an equivalent indenta-
tion is stripped from the remaining lines and
from word. A tab stop is assumed to occur at
every 8 columns for the purposes of determin-
ing the indentation.
<<&digit. See dup(2).
<&digit- The file descriptor specified by digit is
moved to standard input. Similarly for the
standard output using >&digit-.
<&- The standard input is closed. Similarly for
the standard output using >&-.
<&p The input from the co-process is moved to
standard input.
>&p The output to the co-process is moved to stan-
dard output.
<#((expr)) Evaluate arithmetic expression expr and posi-
tion file descriptor 0 to the resulting value
bytes from the start of the file. The vari-
ables CUR and EOF evaluate to the current
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User Commands ksh93(1)
offset and end-of-file offset respectively
when evaluating expr.
>#((expr)) The same as <# except applies to file descrip-
tor 1.
<#pattern Seek forward to the beginning of the next line
containing pattern.
<##pattern The same as <#, except that the portion of the
file that is skipped is copied to standard
output.
If one of the redirection operators is preceded by a digit,
with no intervening space, then the file descriptor number
referred to is that specified by the digit (instead of the
default 0 or 1). If one of the redirection operators other
than >&- and the ># and <# forms, is preceded by {varname}
with no intervening space, then a file descriptor number >
10 is selected by the shell and stored in the variable var-
name. If >&- or the any of the ># and <# forms is preceded
by {varname} the value of varname defines the file descrip-
tor to close or position. For example:
... 2>&1
means file descriptor 2 is to be opened for writing as a
duplicate of file descriptor 1 and
exec [n]fname 2>&1
SunOS 5.11 Last change: 10 Feb 2009 39
User Commands ksh93(1)
first associates file descriptor 1 with file fname. It then
associates file descriptor 2 with the file associated with
file descriptor 1, that is, fname. If the order of redirec-
tions were reversed, file descriptor 2 would be associated
with the terminal (assuming file descriptor 1 had been) and
then file descriptor 1 would be associated with file fname.
If a command is followed by & and job control is not active,
the default standard input for the command is the empty file
/dev/null. Otherwise, the environment for the execution of a
command contains the file descriptors of the invoking shell
as modified by input and output specifications.
Environment
The environment is a list of name-value pairs that is passed
to an executed program in the same way as a normal argument
list. See environ(5).
The names must be identifiers and the values are character
strings. The shell interacts with the environment in several
ways. On invocation, the shell scans the environment and
creates a variable for each name found, giving it the
corresponding value and attributes and marking it export.
Executed commands inherit the environment. If the user modi-
fies the values of these variables or creates new ones,
using the export or typeset -x commands, they become part of
the environment. The environment seen by any executed com-
mand is thus composed of any name-value pairs originally
inherited by the shell, whose values can be modified by the
current shell, plus any additions which must be noted in
export or typeset -x commands. The environment for any
simple-command or function can be augmented by prefixing it
with one or more variable assignments. A variable assignment
argument is a word of the form identifier=value. Thus:
TERM=450 cmd args
and
(export TERM; TERM=450; cmd args)
are equivalent (as far as the execution of cmd is concerned
except for special built-in commands listed in the Built-Ins
section, those that are preceded with a dagger. If the
obsolete -k option is set, all variable assignment arguments
are placed in the environment, even if they occur after the
SunOS 5.11 Last change: 10 Feb 2009 40
User Commands ksh93(1)
command name.
The following example first prints a=b c and then c:
echo a=b c
set -k
echo a=b c
This feature is intended for use with scripts written for
early versions of the shell and its use in new scripts is
strongly discouraged.
Functions
For historical reasons, there are two ways to define func-
tions, the name() syntax and the function name syntax. These
are described in the Commands section of this manual page.
Shell functions are read in and stored internally. Alias
names are resolved when the function is read. Functions are
executed like commands with the arguments passed as posi-
tional parameters. See the Execution section of this manual
page for details.
Functions defined by the function name syntax and called by
name execute in the same process as the caller and share all
files and present working directory with the caller. Traps
caught by the caller are reset to their default action
inside the function. A trap condition that is not caught or
ignored by the function causes the function to terminate and
the condition to be passed on to the caller. A trap on EXIT
set inside a function is executed in the environment of the
caller after the function completes. Ordinarily, variables
are shared between the calling program and the function.
However, the typeset special built-in command used within a
function defines local variables whose scope includes the
current function. They can be passed to functions that they
call in the variable assignment list that precedes the call
or as arguments passed as name references. Errors within
functions return control to the caller.
Functions defined with the name() syntax and functions
defined with the function name syntax that are invoked with
the . special built-in are executed in the caller's environ-
ment and share all variables and traps with the caller.
Errors within these function executions cause the script
SunOS 5.11 Last change: 10 Feb 2009 41
User Commands ksh93(1)
that contains them to abort.
The special built-in command return is used to return from
function calls.
Function names can be listed with the -f or ]f option of the
typeset special built-in command. The text of functions,
when available, is also listed with -f. Functions can be
undefined with the -f option of the unset special built-in
command.
Ordinarily, functions are unset when the shell executes a
shell script. Functions that need to be defined across
separate invocations of the shell should be placed in a
directory and the FPATH variable should contain the name of
this directory. They can also be specified in the ENV file.
Discipline Functions
Each variable can have zero or more discipline functions
associated with it. The shell initially understands the dis-
cipline names get, set, append, and unset but on most sys-
tems others can be added at run time via the C programming
interface extension provided by the builtin built-in util-
ity. If the get discipline is defined for a variable, it is
invoked whenever the specified variable is referenced. If
the variable .sh.value is assigned a value inside the dis-
cipline function, the referenced variable is evaluated to
this value instead. If the set discipline is defined for a
variable, it is invoked whenever the specified variable is
assigned a value. If the append discipline is defined for a
variable, it is invoked whenever a value is appended to the
specified variable. The variable .sh.value is specified the
value of the variable before invoking the discipline, and
the variable is assigned the value of .sh.value after the
discipline completes. If .sh.value is unset inside the dis-
cipline, then that value is unchanged. If the unset discip-
line is defined for a variable, it is invoked whenever the
specified variable is unset. The variable is not unset
unless it is unset explicitly from within this discipline
function.
The variable .sh.name contains the name of the variable for
which the discipline function is called, .sh.subscript is
the subscript of the variable, and .sh.value contains the
value being assigned inside the set discipline function. For
the set discipline, changing .sh.value changes the value
that gets assigned.
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Jobs
If the monitor option of the set command is turned on, an
interactive shell associates a job with each pipeline. It
keeps a table of current jobs, printed by the jobs command,
and assigns them small integer numbers. When a job is
started asynchronously with &, the shell prints a line which
looks like:
[1] 1234
indicating that the job which was started asynchronously was
job number 1 and had one (top-level) process, whose process
id was 1234.
If you are running a job and wish to stop it, CTRL-z sends a
STOP signal to the current job. The shell normally displays
a message that the job has been stopped, and displays
another prompt. You can then manipulate the state of this
job, putting it in the background with the bg command, or
run some other commands and then eventually bring the job
back into the foreground with the foreground command fg. A
CTRL-z takes effect immediately and is like an interrupt in
that pending output and unread input are discarded when it
is typed.
A job being run in the background stops if it tries to read
from the terminal. Background jobs are normally allowed to
produce output, but this can be disabled by giving the com-
mand sttytostop. If you set this tty option, then background
jobs stop when they try to produce output like they do when
they try to read input.
There are several ways to refer to jobs in the shell. A job
can be referred to by the process id of any process of the
job or by one of the following:
%number The job with the specified number.
%string Any job whose command line begins with string.
%?string Any job whose command line contains string.
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User Commands ksh93(1)
%% Current job.
%] Equivalent to %%.
%- Previous job.
The shell learns immediately whenever a process changes
state. It normally informs you whenever a job becomes
blocked so that no further progress is possible, but only
just before it prints a prompt. This is done so that it does
not otherwise disturb your work. The notify option of the
set command causes the shell to print these job change mes-
sages as soon as they occur.
When the monitor option is on, each background job that com-
pletes triggers any trap set for CHLD.
When you try to leave the shell while jobs are running or
stopped, you are warned that You have stopped(running) jobs.
You can use the jobs command to see what they are. If you
immediately try to exit again, the shell does not warn you a
second time, and the stopped jobs are terminated. When a
login shell receives a HUP signal, it sends a HUP signal to
each job that has not been disowned with the disown built-in
command.
Signals
The INT and QUIT signals for an invoked command are ignored
if the command is followed by & and the monitor option is
not active. Otherwise, signals have the values inherited by
the shell from its parent. See the trap built-in command.
Execution
Each time a command is read, the substitutions are carried
out. If the command name matches one of the ones in the Spe-
cial Built-in Commands section of this manual page, it is
executed within the current shell process. Next, the command
name is checked to see if it matches a user defined func-
tion. If it does, the positional parameters are saved and
then reset to the arguments of the function call. A function
is also executed in the current shell process. When the
function completes or issues a return, the positional param-
eter list is restored. For functions defined with the func-
tion name syntax, any trap set on EXIT within the function
is executed. The exit value of a function is the value of
the last command executed. If a command name is not a
SunOS 5.11 Last change: 10 Feb 2009 44
User Commands ksh93(1)
special built-in command or a user defined function, but it
is one of the built-in commands, it is executed in the
current shell process.
The shell variable PATH defines the search path for the
directory containing the command. Alternative directory
names are separated by a colon (:). The default path is
/bin:/usr/bin:, specifying /bin, /usr/bin, and the current
directory in that order. The current directory can be speci-
fied by two or more adjacent colons, or by a colon at the
beginning or end of the path list. If the command name con-
tains a slash (/), the search path is not used. Otherwise,
each directory in the path is searched for an executable
file of the specified name that is not a directory. If
found, and if the shell determines that there is a built-in
version of a command corresponding to a specified pathname,
this built-in is invoked in the current process. If found,
and this directory is also contained in the value of the
FPATH variable, then this file is loaded into the current
shell environment as if it were the argument to the . com-
mand except that only preset aliases are expanded, and a
function of the specified name is executed as described in
this manual page. If not found, and the file .paths is
found, and this file contains a line of the form FPATH=path
where path is an existing directory, and this directory con-
tains a file of the specified name, then this file is loaded
into the current shell environment as if it were the argu-
ment to the . special built-in command and a function of the
specified name is executed. Otherwise, if found, a process
is created and an attempt is made to execute the command
using exec(2).
When an executable is found, the directory where it is found
in is searched for a file named .paths. If this file is
found and it contains a line of the form BUILTINLIB=value,
the library named by value is searched for as if it were an
option argument to builtin -f, and if it contains a built-in
of the specified name this is executed instead of a command
by this name. Otherwise, if this file is found and it con-
tains a line of the form name=value in the first or second
line, then the environment variable name is modified by
prepending the directory specified by value to the directory
list. If value is not an absolute directory, then it speci-
fies a directory relative to the directory that the execut-
able was found. If the environment variable name does not
already exist it is added to the environment list for the
specified command.
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User Commands ksh93(1)
If the file has execute permission but is not an a.out file,
it is assumed to be a file containing shell commands. A
separate shell is spawned to read it. All non-exported vari-
ables are removed in this case. If the shell command file
doesn't have read permission, and/or if the setuid and set-
gid bits are set on the file, then the shell executes an
agent whose job it is to set up the permissions and execute
the shell with the shell command file passed down as an open
file. A parenthesized command is executed in a sub-shell
without removing non-exported variables.
Command Re-entry
The text of the last HISTSIZE (default 512) commands entered
from a terminal device is saved in a history file. The file
$HOME/.shhistory is used if the HISTFILE variable is not
set or if the file it names is not writable. A shell can
access the commands of all interactive shells which use the
same named HISTFILE. The built-in command hist is used to
list or edit a portion of this file. The portion of the file
to be edited or listed can be selected by number or by giv-
ing the first character or characters of the command. A sin-
gle command or range of commands can be specified. If you do
not specify an editor program as an argument to hist then
the value of the variable HISTEDIT is used. If HISTEDIT is
unset, the obsolete variable FCEDIT is used. If FCEDIT is
not defined, then /bin/ed is used. The edited commands are
printed and executed again upon leaving the editor unless
you quit without writing. The -s option (and in obsolete
versions, the editor name -) is used to skip the editing
phase and to re-execute the command. In this case a substi-
tution parameter of the form old=newcan be used to modify
the command before execution. For example, with the preset
alias r, which is aliased to 'hist -s', typing `r bad=good
c' re-executes the most recent command which starts with the
letter c, replacing the first occurrence of the string bad
with the string good.
Inline Editing Options
Normally, each command line entered from a terminal device
is simply typed followed by a NEWLINE (RETURN or LINE FED).
If either the emacs, gmacs, or vi option is active, the user
can edit the command line. To be in either of these edit
modes set the corresponding option. An editing option is
automatically selected each time the VISUAL or EDITOR vari-
able is assigned a value ending in either of these option
names.
The editing features require that the user's terminal accept
RETURN as carriage return without line feed and that a SPACE
must overwrite the current character on the screen.
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Unless the multiline option is on, the editing modes imple-
ment a concept where the user is looking through a window at
the current line. The window width is the value of COLUMNS
if it is defined, otherwise 80. If the window width is too
small to display the prompt and leave at least 8 columns to
enter input, the prompt is truncated from the left. If the
line is longer than the window width minus two, a mark is
displayed at the end of the window to notify the user. As
the cursor moves and reaches the window boundaries the win-
dow is centered about the cursor. The mark is a > (<, *) if
the line extends on the right , left, or both sides of the
window.
The search commands in each edit mode provide access to the
history file. Only strings are matched, not patterns,
although a leading ^ in the string restricts the match to
begin at the first character in the line.
Each of the edit modes has an operation to list the files or
commands that match a partially entered word. When applied
to the first word on the line, or the first word after a ;,
, &, or (, and the word does not begin with ~ or contain a
/, the list of aliases, functions, and executable commands
defined by the PATH variable that could match the partial
word is displayed. Otherwise, the list of files that match
the specified word is displayed. If the partially entered
word does not contain any file expansion characters, a * is
appended before generating these lists. After displaying the
generated list, the input line is redrawn. These operations
are called command name listing and file name listing,
respectively. There are additional operations, referred to
as command name completion and file name completion, which
compute the list of matching commands or files, but instead
of printing the list, replace the current word with a com-
plete or partial match. For file name completion, if the
match is unique, a / is appended if the file is a directory
and a space is appended if the file is not a directory. Oth-
erwise, the longest common prefix for all the matching files
replaces the word. For command name completion, only the
portion of the file names after the last / are used to find
the longest command prefix. If only a single name matches
this prefix, then the word is replaced with the command name
followed by a space. When using a TAB for completion that
does not yield a unique match, a subsequent TAB provides a
numbered list of matching alternatives. A specific selection
can be made by entering the selection number followed by a
TAB.
Key Bindings
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User Commands ksh93(1)
The KEYBD trap can be used to intercept keys as they are
typed and change the characters that are actually seen by
the shell. This trap is executed after each character (or
sequence of characters when the first character is ESC) is
entered while reading from a terminal.
The variable .sh.edchar contains the character or character
sequence which generated the trap. Changing the value of
.sh.edchar in the trap action causes the shell to behave as
if the new value were entered from the keyboard rather than
the original value. The variable .sh.edcol is set to the
input column number of the cursor at the time of the input.
The variable .sh.edmode is set to ESC when in vi insert mode
and is null otherwise. By prepending ${.sh.editmode} to a
value assigned to .sh.edchar it causes the shell to change
to control mode if it is not already in this mode.
This trap is not invoked for characters entered as arguments
to editing directives, or while reading input for a charac-
ter search.
emacs Editing Mode
This mode is entered by enabling either the emacs or gmacs
option. The only difference between these two modes is the
way they handle ^T. To edit, the user moves the cursor to
the point needing correction and then inserts or deletes
characters or words as needed. All the editing commands are
control characters or escape sequences. The notation for
control characters is caret (^) followed by the character.
For example, ^F is the notation for CTRL/F. This is entered
by depressing f while holding down the CTRL (control) key.
The SHIFT key is not depressed. (The notation ^? indicates
the DEL (delete) key.)
The notation for escape sequences is M- followed by a char-
acter. For example, M-f (pronounced Meta f) is entered by
depressing ESC (ASCI 033) followed by f. M-F is the nota-
tion for ESC followed by F.
All edit commands operate from any place on the line, not
just at the beginning. The RETURN or the LINE FED key is
not entered after edit commands except when noted.
^F Move the cursor forward (right) one character.
SunOS 5.11 Last change: 10 Feb 2009 48
User Commands ksh93(1)
M-[C Move the cursor forward (right) one character.
M-f Move the cursor forward one word. The emacs
editor's idea of a word is a string of charac-
ters consisting of only letters, digits and
underscores.
^B Move the cursor backward (left) one character.
M-[D Move the cursor backward (left) one character.
M-b Move the cursor backward one word.
^A Move the cursor to the beginning of the line.
M-[H Move the cursor to the beginning of the line.
^E Move the cursor to the end of the line.
M-[Y Move the cursor to the end of line.
^]char Move the cursor forward to the character char
on the current line.
M-^]char Move the cursor backwards to the character char
on the current line.
^X^X Interchange the cursor and the mark.
erase Delete the previous character. The user-defined
erase character is defined by the stty(1) com-
mand, and is usually ^H or #.
lnext Removes the next character's editing features.
The user-defined literal next character is
defined by the stty(1) command, or is ^V if not
defined.
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User Commands ksh93(1)
^D Delete the current character.
M-d Delete the current word.
M-^H MetaBACKSPACE. Delete the previous word.
M-h Delete the previous word.
M-^? MetaDEL. Delete the previous word. If your
interrupt character is ^? (DEL, the default),
this command does not work.
^T Transpose the current character with the previ-
ous character, and advance the cursor in emacs
mode. Transpose two previous characters in
gmacs mode.
^C Capitalize the current character.
M-c Capitalize the current word.
M-l Change the current word to lower case.
^K Delete from the cursor to the end of the line.
If preceded by a numerical parameter whose
value is less than the current cursor position,
delete from specified position up to the cur-
sor. If preceded by a numerical parameter whose
value is greater than the current cursor posi-
tion, then delete from cursor up to specified
cursor position.
^W Kill from the cursor to the mark.
M-p Push the region from the cursor to the mark on
the stack.
kill Kill the entire current line. The user-defined
kill character is defined by the stty(1) com-
mand, usually a ^G or @. If two kill characters
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User Commands ksh93(1)
are entered in succession, all kill characters
from then on cause a line feed. This is useful
when using paper terminals.
^Y Restore the last item removed from line. Yank
the item back to the line.
^L Line feed and print the current line.
M-^L Clear the screen.
^@ Null character. Set mark.
M-space MetaSPACE. Set the mark.
^J New line. Execute the current line.
^M Return. Execute the current line.
EOF End-of-file character, normally ^D, is pro-
cessed as an end-of-file only if the current
line is null.
^P Fetch the previous command. Each time ^P is
entered the previous command back in time is
accessed. Moves back one line when it is not on
the first line of a multi-line command.
M-[A Equivalent to ^P.
M-< Fetch the least recent (oldest) history line.
M-> Fetch the most recent (youngest) history line.
^N Fetch the next command line. Each time ^N is
entered the next command line forward in time
is accessed.
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User Commands ksh93(1)
M-[B Equivalent to ^N.
^Rstring Reverse search history for a previous command
line containing string. If a parameter of zero
is specified, the search is forward. string is
terminated by a RETURN or NEWLINE. If string is
preceded by a ^, the matched line must begin
with string. If string is omitted, then the
next command line containing the most recent
string is accessed. In this case a parameter of
zero reverses the direction of the search.
^O Operate. Execute the current line and fetch the
next line relative to current line from the
history file.
M-digits Escape. Define numeric parameter. The digits
are taken as a parameter to the next command.
The commands that accept a parameter are: ^F,
^B, ERASE, ^C, ^D, ^K, ^R, ^P, ^N, ^], M-., M-,
M-^], M-, M-=, M-b, M-c, M-d, M-f, M-h, M-l,
and M-^H.
M-letter Soft-key. Search the alias list for an alias by
the name letter. If an alias of letter is
defined, insert its value on the input queue.
letter must not be one of the metafunctions in
this section.
M-[letter Soft key. Search the alias list for an alias by
the name letter. If an alias of this name is
defined, insert its value on the input queue.
This can be used to program function keys on
many terminals.
M-. The last word of the previous command is
inserted on the line. If preceded by a numeric
parameter, the value of this parameter deter-
mines which word to insert rather than the last
word.
M- Same as M-..
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User Commands ksh93(1)
M-* Attempt filename generation on the current
word. As asterisk is appended if the word does
not match any file or contain any special pat-
tern characters.
M-ESC Command or file name completion as described in
this manual page.
^ITAB Attempts command or file name completion as
described in this manual page. If a partial
completion occurs, repeating this behaves as if
M-= were entered. If no match is found or
entered after SPACE, a TAB is inserted.
M-= If not preceded by a numeric parameter, gen-
erates the list of matching commands or file
names as described in this manual page. Other-
wise, the word under the cursor is replaced by
the item corresponding to the value of the
numeric parameter from the most recently gen-
erated command or file list. If the cursor is
not on a word, the word is inserted instead.
^U Multiply parameter of next command by 4.
\ Escape the next character. Editing characters,
the user's erase, kill and interrupt (normally
^?) characters can be entered in a command line
or in a search string if preceded by a \. The \
removes the next character's editing features,
if any.
M-^V Display the version of the shell.
M-# If the line does not begin with a #, a # is
inserted at the beginning of the line and after
each NEWLINE, and the line is entered. This
causes a comment to be inserted in the history
file. If the line begins with a #, the # is
deleted and one # after each NEWLINE is also
deleted.
vi Editing Mode
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There are two typing modes. Initially, when you enter a com-
mand you are in the input mode. To edit, the user enters
control mode by typing ESC (033) and moves the cursor to the
point needing correction and then inserts or deletes charac-
ters or words as needed. Most control commands accept an
optional repeat count prior to the command.
When in vi mode on most systems, canonical processing is
initially enabled and the command is echoed again if the
speed is 1200 baud or greater and it contains any control
characters or less than one second has elapsed since the
prompt was printed. The ESC character terminates canonical
processing for the remainder of the command and the user can
then modify the command line. This scheme has the advantages
of canonical processing with the type-ahead echoing of raw
mode.
If the option viraw is also set, the terminal is always have
canonical processing disabled. This mode is implicit for
systems that do not support two alternate end of line delim-
iters, and might be helpful for certain terminals.
Input Edit Commands
By default the editor is in input mode.
The following input edit commands are supported:
ERASE User defined erase character as defined by the
stty command, usually ^H or #. Delete previous
character.
^W Delete the previous blank separated word. On some
systems the viraw option might be required for
this to work.
EOF As the first character of the line causes the
shell to terminate unless the ignoreeof option is
set. Otherwise this character is ignored.
lnext User defined literal next character as defined by
the stty(1) or ^V if not defined. Removes the next
character's editing features, if any. On some sys-
tems the viraw option might be required for this
to work.
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\ Escape the next ERASE or KIL character.
^I TAB Attempts command or file name completion as
described in this manual page and returns to input
mode. If a partial completion occurs, repeating
this behaves as if = were entered from control
mode. If no match is found or entered after SPACE,
a TAB is inserted.
Motion Edit Commands
The motion edit commands move the cursor.
The following motion edit commands are supported:
[count]l Move the cursor forward (right) one character.
[count][C Move the cursor forward (right) one character.
[count]w Move the cursor forward one alphanumeric word.
[count]W Move the cursor to the beginning of the next
word that follows a blank.
[count]e Move the cursor to the end of the word.
[count]E Move the cursor to the end of the current blank
delimited word.
[count]h Move the cursor backward (left) one character.
[count][D Move the cursor backward (left) one character.
[count]b Move the cursor backward one word.
[count]B Move the cursor to the preceding blank
separated word.
[count] Move the cursor to column count.
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[count]fc Find the next character c in the current line.
[count]Fc Find the previous character c in the current
line.
[count]tC Equivalent to f followed by h.
[count]Tc Equivalent to F followed by l.
[count]; Repeat count times the last single character
find command: f, F, t, or T.
[count], Reverse the last single character find command
count times.
0 Move the cursor to the start of line.
^ Move the cursor to start of line.
[H Move the cursor to the first non-blank charac-
ter in the line.
$ Move the cursor to the end of the line.
[Y Move the cursor to the end of the line.
% Moves to balancing (, ), {, }, [, or ]. If cur-
sor is not on one of the characters described
in this section, the remainder of the line is
searched for the first occurrence of one of the
characters first.
Search Edit Commands
The search edit commands access your command history.
The following search edit commands are supported:
[count]k Fetch the previous command. Each time k is
entered, the previous command back in time is
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accessed.
[count]- Fetch the previous command. Each time k is
entered, the previous command back in time is
accessed.
Equivalent to k.
[count][A Fetch the previous command. Each time k is
entered, the previous command back in time is
accessed.
Equivalent to k.
[count]j Fetch the next command. Each time j is entered,
the next command forward in time is accessed.
[count] Fetch the next command. Each time j is entered,
the next command forward in time is accessed.
Equivalent to j.
[count][B Fetch the next command. Each time j is entered,
the next command forward in time is accessed.
Equivalent to j.
[count]G Fetch command number count. The default is the
least recent history command.
/string Search backward through history for a previous
command containing string. string is terminated
by a RETURN or NEWLINE. If string is preceded
by a ^, the matched line must begin with
string. If string is null, the previous string
is used.
?string Search forward through history for a previous
command containing string. string is terminated
by a RETURN or NEWLINE. If string is preceded
by a ^, the matched line must begin with
string. If string is null, the previous string
is used.
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Same as / except that search is in the forward
direction.
n Search in the backwards direction for the next
match of the last pattern to / or ? commands.
N Search in the forward direction for next match
of the last pattern to / or ?.
Text Modification Edit Commands
The following commands modify the line:
a Enter input mode and enter text after the
current character.
A Append text to the end of the line.
Equivalent to $a.
[count]cmotion Delete current character through the
c[count]motion character that motion would move the cur-
sor to and enter input mode. If motion is
c, the entire line is deleted and input
mode entered.
C Delete the current character through the
end of line and enter input mode.
Equivalent to c$.
S Equivalent to cc.
[count]s Replace characters under the cursor in
input mode.
D[count]dmotion Delete the current character through the
end of line. Equivalent to d$.
d[count]motion Delete current character through the
character that motion would move to. If
motion is d , the entire line is deleted.
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i Enter input mode and insert text before
the current character.
I Insert text before the beginning of the
line. Equivalent to 0i.
[count]P Place the previous text modification
before the cursor.
[count]p Place the previous text modification
after the cursor.
R Enter input mode and replace characters
on the screen with characters you type
overlay fashion.
[count]rc Replace the count characters starting at
the current cursor position with c, and
advance the cursor.
[count]x Delete current character.
[count]X Delete preceding character.
[count]. Repeat the previous text modification
command.
[count]~ Invert the case of the count characters
starting at the current cursor position
and advance the cursor.
[count] Causes the count word of the previous
command to be appended and input mode
entered. The last word is used if count
is omitted.
* Causes an * to be appended to the current
word and file name generation attempted.
If no match is found, it rings the bell.
Otherwise, the word is replaced by the
matching pattern and input mode is
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entered.
\ Command or file name completion as
described in this manual page.
Other Edit Commands
The following miscellaneous edit commands are supported:
[count]ymotion Yank the current character through the
y[count]motion character to which motion would move the
cursor. Put the yanked characters in the
delete buffer. The text and cursor posi-
tion are unchanged.
yy Yank the current line.
Y Yank the current line from the current
cursor location to the end of the line.
Equivalent to y$.
u Undo the last text modifying command.
U Undo all the text modifying commands per-
formed on current line.
[count]V Return the command :
hist -e ${VISUAL:-${EDITOR:-vi}} count
in the input buffer. If count is omitted,
the current line is used.
^L Line feed and print the current line. This
command only works in control mode.
^J New line. Execute the current line,
regardless of mode.
^M Return. Execute the current line, regard-
less of mode.
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# If the first character of the command is a
# , delete this # and each # that follows
a NEWLINE.
Otherwise, send the line after inserting a
# in front of each line in the command.
This is command is useful for causing the
current line to be inserted in the history
as a comment and un-commenting previously
commented commands in the history file.
[count]= If count is not specified, generate the
list of matching commands or file names as
described in this manual page.
Otherwise, replace the word at the current
cursor location with the count item from
the most recently generated command or
file list. If the cursor is not on a word,
it is inserted after the current cursor
location.
@letter Search your alias list for an alias by the
name letter. If an alias of this name is
defined, insert its value on the input
queue for processing.
^V Display version of the shell.
Built-in Commands
The following simple-commands are executed in the shell pro-
cess. Input and output redirection is permitted. Unless oth-
erwise indicated, the output is written on file descriptor 1
and the exit status, when there is no syntax error, is 0.
Except for :, true, false, echo, newgrp, and login, all
built-in commands accept -- to indicate the end of options.
They also interpret the option --man as a request to display
the manual page onto standard error and -? as a help request
which prints a usage message on standard error.
Commands that are preceded by one or two ] symbols are spe-
cial built-in commands and are treated specially in the fol-
lowing ways:
1. Variable assignment lists preceding the command
remain in effect when the command completes.
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2. I/O redirections are processed after variable
assignments.
3. Errors cause a script that contains them to abort.
4. They are not valid function names.
5. Words following a command preceded by ] that are
in the format of a variable assignment are expanded
with the same rules as a variable assignment. This
means that tilde substitution is performed after
the = sign and field splitting and file name gen-
eration are not performed.
] : [arg ...]
The command only expands parameters.
] . name [arg ...]
If name is a function defined with the function name
reserved word syntax, the function is executed in the
current environment (as if it had been defined with the
name() syntax.) Otherwise if name refers to a file, the
file is read in its entirety and the commands are exe-
cuted in the current shell environment. The search path
specified by PATH is used to find the directory contain-
ing the file. If any arguments arg are specified, they
become the positional parameters while processing the .
command and the original positional parameters are
restored upon completion. Otherwise the positional
parameters are unchanged. The exit status is the exit
status of the last command executed.
] alias [-ptx] [name[ =value] ...
alias with no arguments prints the list of aliases in
the form name=value on standard output. The -p option
causes the word alias to be inserted before each one.
When one or more arguments are specified, an alias is
defined for each name whose value is specified. A trail-
ing space in value causes the next word to be checked
for alias substitution. The obsolete -t option is used
to set and list tracked aliases. The value of a tracked
alias is the full pathname corresponding to the speci-
fied name. The value becomes undefined when the value of
PATH is reset but the alias remains tracked. Without the
-t option, for each name in the argument list for which
no value is specified, the name and value of the alias
is printed. The obsolete -x option has no effect. The
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exit status is non-zero if a name is specified, but no
value, and no alias has been defined for the name.
bg [ job...]
This command is only on systems that support job con-
trol. Puts each specified job into the background. The
current job is put in the background if job is not
specified. See the Jobs section of this manual page for
a description of the format of job.
] break [n]
Exit from the enclosing for, while, until, or select
loop, if any. If n is specified, then break n levels.
builtin [-ds ] [-f file] [name ...]
If name is not specified, and no -f option is specified,
the built-ins are printed on standard output. The -s
option prints only the special built-ins. Otherwise,
each name represents the pathname whose basename is the
name of the built-in. The entry point function name is
determined by prepending b to the built-in name. The ISO
C/C] prototype is bmycommand(int argc, char *argv[],
void *context) for the built-in command mycommand where
argv is an array of argc elements and context is an
optional pointer to a Shellt structure as described in
Special built-ins cannot be bound to a
pathname or deleted. The -d option deletes each of the
specified built-ins. On systems that support dynamic
loading, the -f option names a shared library containing
the code for built-ins. The shared library prefix and/or
suffix, which depend on the system, can be omitted. Once
a library is loaded, its symbols become available for
subsequent invocations of builtin. Multiple libraries
can be specified with separate invocations of the buil-
tin command. Libraries are searched in the reverse order
in which they are specified. When a library is loaded,
it looks for a function in the library whose name is
libinit() and invokes this function with an argument of
0.
cd [-LP] [arg]
cd [-LP] old new
This command has two forms.
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In the first form it changes the current directory to
arg. If arg is a -, the directory is changed to the pre-
vious directory. The shell variable HOME is the default
arg. The variable PWD is set to the current directory.
The shell variable CDPATH defines the search path for
the directory containing arg. Alternative directory
names are separated by a colon (:). The default path is
NUL (specifying the current directory). The current
directory is specified by a null path name, which can
appear immediately after the equal sign or between the
colon delimiters anywhere else in the path list. If arg
begins with a /, the search path is not used. Otherwise,
each directory in the path is searched for arg.
The second form of cd substitutes the string new for the
string old in the current directory name, PWD, and tries
to change to this new directory. By default, symbolic
link names are treated literally when finding the direc-
tory name. This is equivalent to the -L option. The -P
option causes symbolic links to be resolved when deter-
mining the directory. The last instance of -L or -P on
the command line determines which method is used. The cd
command cannot be executed by rksh93.
command [-pvVx] name [arg ...]
Without the -v or -V options, executes name with the
arguments specified by arg.
The -p option causes a default path to be searched
rather than the one defined by the value of PATH. Func-
tions are not searched when finding name. In addition,
if name refers to a special built-in, none of the spe-
cial properties associated with the leading daggers are
honored. For example, the predefined alias
redirect='command exec' prevents a script from terminat-
ing when an invalid redirection is specified.
With the -x option, if command execution would result in
a failure because there are too many arguments, errno
E2BIG, the shell invokes command name multiple times
with a subset of the arguments on each invocation. Argu-
ments that occur prior to the first word that expands to
multiple arguments and after the last word that expands
to multiple arguments are passed on each invocation. The
exit status is the maximum invocation exit status.
With the -v option, command is equivalent to the built-
in whence command described in this section. The -V
option causes command to act like whence -v.
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]continue [n]
Resumes the next iteration of the enclosing for, while,
until, or select loop. If n is specified, then resume at
the nth enclosing loop.
disown [job...]
Causes the shell not to send a HUP signal to each speci-
fied job, or all active jobs if job is omitted, when a
login shell terminates.
echo [arg ...]
When the first arg does not begin with a -, and none of
the arguments contain a backslash (\), prints each of
its arguments separated by a SPACE and terminated by a
NEWLINE. Otherwise, the behavior of echo is system
dependent and print or printf described in this section
should be used. See echo(1) for usage and description.
]eval [arg ...]
The arguments are read as input to the shell and the
resulting commands are executed.
]exec [-c] [-a name ...] [arg ...]
If arg is specified, the command specified by the argu-
ments is executed in place of this shell without creat-
ing a new process. The -c option causes the environment
to be cleared before applying variable assignments asso-
ciated with the exec invocation. The -a option causes
name rather than the first arg, to become argv[0] for
the new process. Input and output arguments can appear
and affect the current process. If arg is not specified,
the effect of this command is to modify file descriptors
as prescribed by the input/output redirection list. In
this case, any file descriptor numbers greater than 2
that are opened with this mechanism are closed when
invoking another program.
]exit [n]
Causes the shell to exit with the exit status specified
by n. The value is the least significant 8 bits of the
specified status. If n is omitted, then the exit status
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is that of the last command executed. An end-of-file
also causes the shell to exit except for a shell which
has the ignoreeof option turned on. See set.
]export [-p] [name[=value] ...
If name is not specified, the names and values of each
variable with the export attribute are printed with the
values quoted in a manner that allows them to be re-
entered. The -p option causes the word export to be
inserted before each one. Otherwise, the specified names
are marked for automatic export to the environment of
subsequently-executed commands.
false
Does nothing, and exits 1. Used with until for infinite
loops.
fg [job ...]
This command is only on systems that support job con-
trol. Each job specified is brought to the foreground
and waited for in the specified order. Otherwise, the
current job is brought into the foreground. See Jobs for
a description of the format of job.
getconf [name [pathname]
Prints the current value of the configuration parameter
specified by name. The configuration parameters are
defined by the IE POSIX 1003.1 and IE POSIX 1003.2
standards. See pathconf(2) and sysconf(3C).
The pathname argument is required for parameters whose
value depends on the location in the file system. If no
arguments are specified, getconf prints the names and
values of the current configuration parameters. The
pathname / is used for each of the parameters that
requires pathname.
getopts [ -a name] optstring vname [arg ...]
Checks arg for legal options. If arg is omitted, the
positional parameters are used. An option argument
begins with a ] or a -. An option that does not begin
with ] or - or the argument -- ends the options. Options
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beginning with ] are only recognized when optstring
begins with a ]. optstring contains the letters that
getopts recognizes. If a letter is followed by a :, that
option is expected to have an argument. The options can
be separated from the argument by blanks. The option
-?causes getopts to generate a usage message on standard
error. The -a option can be used to specify the name to
use for the usage message, which defaults to $0. getopts
places the next option letter it finds inside variable
vname each time it is invoked. The option letter is
prepended with a ] when arg begins with a ]. The index
of the next arg is stored in OPTIND. The option argu-
ment, if any, gets stored in OPTARG. A leading : in opt-
string causes getopts to store the letter of an invalid
option in OPTARG, and to set vname to ? for an unknown
option and to: when a required option argument is miss-
ing. Otherwise, getopts prints an error message. The
exit status is non-zero when there are no more options.
There is no way to specify any of the options :, ], -,
?, [, and ]. The option # can only be specified as the
first option.
hist [ -e ename][-nlr] [ first[last ] ]
hist -s [ old=new ] [ command]
In the first form, a range of commands from first to
last is selected from the last HISTSIZE commands that
were typed at the terminal. The arguments first and last
can be specified as a number or as a string. A string is
used to locate the most recent command starting with the
specified string. A negative number is used as an offset
to the current command number. If the -l option is
selected, the commands are listed on standard output.
Otherwise, the editor program ename is invoked on a file
containing these keyboard commands. If ename is not sup-
plied, then the value of the variable HISTEDIT is used.
If HISTEDIT is not set, then FCEDIT (default /bin/ed) is
used as the editor. When editing is complete, the edited
command(s) is executed if the changes have been saved.
If last is not specified, then it is set to first. If
first is not specified, the default is the previous com-
mand for editing and -16 for listing. The option -r rev-
erses the order of the commands and the option -n
suppresses command numbers when listing. In the second
form, command is interpreted as first described in this
section and defaults to the last command executed. The
resulting command is executed after the optional substi-
tution old=new is performed.
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jobs -lnp [job ...]
Lists information about each specified job, or all
active jobs if job is omitted. The -l option lists pro-
cess ids in addition to the normal information. The -n
option only displays jobs that have stopped or exited
since last notified. The -p option causes only the pro-
cess group to be listed. See Jobs for a description of
the format of job.
kill [-s signame] job ...
kill [-n signum] job ...
kill -l [sig ...]
Sends either the TERM (terminate) signal or the speci-
fied signal to the specified jobs or processes. Signals
are either specified by number with the -n option or by
name with the -s option (as specified in ,
stripped of the prefix `SIG with the exception that
SIGCLD is named CHLD). For backward compatibility, the n
and s can be omitted and the number or name placed
immediately after the -. If the signal being sent is
TERM (terminate) or HUP (hang up), then the job or pro-
cess is sent a CONT (continue) signal if it is stopped.
The argument job can be the process id of a process that
is not a member of one of the active jobs. See Jobs for
a description of the format of job. In the third form,
kill -l, if sig is not specified, the signal names are
listed. Otherwise, for each sig that is a name, the
corresponding signal number is listed. For each sig that
is a number, the signal name corresponding to the least
significant 8 bits of sig is listed.
let [arg ...]
Each arg is a separate arithmetic expression to be
evaluated. See the Arithmetic Evaluation section of this
manual page for a description of arithmetic expression
evaluation. The exit status is 0 if the value of the
last expression is non-zero, and 1 otherwise.
]newgrp [arg ...]
Equivalent to exec /bin/newgrp arg ...
print [-Renprs] [ -u unit] [ -f format ] [ arg ...]
With no options or with option - or --, each arg is
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printed on standard output. The -f option causes the
arguments to be printed as described by printf. In this
case, any e, n, r, or R options are ignored. Otherwise,
unless the -R or -r, are specified, the following escape
conventions are applied:
\a Alert character (ASCI 07)
\b Backspace character (ASCI 010)
\c Causes print to end without processing more
arguments and not adding a NEWLINE
\f Form-feed character (ASCI 014)
\n NEWLINE character (ASCI 012)
\r RETURN character (ASCI 015)
\t TAB character (ASCI 011)
\v Vertical TAB character (ASCI 013)
\E Escape character (ASCI 033)
\\ Backslash character \
\0x Character defined by the 1, 2, or 3-digit octal
string specified by x
The -R option prints all subsequent arguments and
options other than -n. The -e causes the escape conven-
tions to be applied This is the default behavior. It
reverses the effect of an earlier -r. The -p option
causes the arguments to be written onto the pipe of the
process spawned with & instead of standard output. The
-s option causes the arguments to be written onto the
history file instead of standard output. The -u option
can be used to specify a one digit file descriptor unit
number unit on which the output is placed. The default
is 1. If the option -n is used, no NEWLINE is added to
the output.
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printf format[arg ...]
The arguments arg are printed on standard output in
accordance with the ANSI-C formatting rules associated
with the format string format. If the number of argu-
ments exceeds the number of format specifications, the
format string is reused to format remaining arguments.
The following extensions can also be used: A %b format
can be used instead of %s to cause escape sequences in
the corresponding arg to be expanded as described in
print. A %B option causes each of the arguments to be
treated as variable names and the binary value of the
variables is printed. This is most useful for variables
with an attribute of b. A %H format can be used instead
of %s to cause characters in arg that are special in
HTML and XML to be output as their entity name. A %P
format can be used instead of %s to cause arg to be
interpreted as an extended regular expression and be
printed as a shell pattern. A %R format can be used
instead of %s to cause arg to be interpreted as a shell
pattern and to be printed as an extended regular expres-
sion. A %q format can be used instead of %s to cause the
resulting string to be quoted in a manner than can be
input again to the shell. A %(date-format)T format can
be use to treat an argument as a date/time string and to
format the date/time according to the date-format as
defined for the date(1) command. A %Z format outputs a
byte whose value is 0. The precision field of the %d
format can be followed by a . and the output base. In
this case, the # flag character causes base# to be
prepended. The # flag when used with the d specifier
without an output base, causes the output to be
displayed in thousands units with one of the suffixes k
M G T P E to indicate the unit. The # flag when used
with the i specifier causes the output to be displayed
in 1024 with one of the suffixes Ki Mi Gi Ti Pi Ei to
indicate the unit. The = flag has been added to center
the output within the specified field width.
pwd [-LP]
Outputs the value of the current working directory. The
-L option is the default. It prints the logical name of
the current directory. If the -P option is specified,
all symbolic links are resolved from the name. The last
instance of -L or -P on the command line determines
which method is used.
read [-Aprs] [-d delim] [ -n n] [ -N n] [-t timeout] [-u
unit] [vname?prompt] [ vname ... ]
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The shell input mechanism. One line is read and is bro-
ken up into fields using the characters in IFS as
separators. The escape character, \, is used to remove
any special meaning for the next character and for line
continuation. The -d option causes the read to continue
to the first character of delim rather than NEWLINE. The
-n option causes at most n bytes to read rather a full
line but returns when reading from a slow device as soon
as any characters have been read. The -N option causes
exactly n to be read unless an end-of-file has been
encountered or the read times out because of the -t
option. In raw mode, -r, the \ character is not treated
specially. The first field is assigned to the first
vname, the second field to the second vname, etc., with
leftover fields assigned to the last vname. When vname
has the binary attribute and -n or -N is specified, the
bytes that are read are stored directly into the vari-
able. If the -v is specified, then the value of the
first vname is used as a default value when reading from
a terminal device. The -A option causes the variable
vname to be unset and each field that is read to be
stored in successive elements of the indexed array
vname. The -p option causes the input line to be taken
from the input pipe of a process spawned by the shell
using &. If the -s option is present, the input is
saved as a command in the history file. The option -u
can be used to specify a one digit file descriptor unit
unit to read from. The file descriptor can be opened
with the exec special built-in command. The default
value of unit n is 0. The option -t is used to specify a
time out in seconds when reading from a terminal or
pipe. If vname is omitted, then REPLY is used as the
default vname. An end-of-file with the -p option causes
cleanup for this process so that another can be spawned.
If the first argument contains a ?, the remainder of
this word is used as a prompt on standard error when the
shell is interactive. The exit status is 0 unless an
end-of-file is encountered or read has timed out.
]readonly [-p] [ vname[=value] ...
If vname is not specified, the names and values of each
variable with the read-only attribute is printed with
the values quoted in a manner that allows them to be
input again. The -p option causes the word readonly to
be inserted before each one. Otherwise, the specified
vnames are marked readonly and these names cannot be
changed by subsequent assignment.
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]return [n]
Causes a shell function or script to return to the
invoking script with the exit status specified by n. The
value is the least significant 8 bits of the specified
status. If n is omitted, then the return status is that
of the last command executed. If return is invoked while
not in a function or a script, then it behaves the same
as exit.
]set [ ]BCGabefhkmnoprstuvx] []o [ option ] ] ... [ ]A
vname] [arg...]
The set command supports the following options:
-a
All subsequent variables that are defined are
automatically exported.
-A
Array assignment. Unset the variable vname and
assign values sequentially from the arg list. If ]A
is used, the variable vname is not unset first.
-b
Prints job completion messages as soon as a back-
ground job changes state rather than waiting for the
next prompt.
-B
Enable brace pattern field generation. This is the
default behavior.
-C
Prevents redirection (>) from truncating existing
files. Files that are created are opened with the
OEXCL mode. Requires > to truncate a file when
turned on.
-e
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If a command has a non-zero exit status, execute the
ER trap, if set, and exit. This mode is disabled
while reading profiles.
-f
Disables file name generation.
-G
Causes the pattern ** by itself to match files and
zero or more directories and subdirectories when
used for file name generation. If followed by a /
only directories and subdirectories are matched.
-h
Each command becomes a tracked alias when first
encountered.
-k
Obsolete. All variable assignment arguments are
placed in the environment for a command, not just
those that precede the command name.
-m
Background jobs run in a separate process group and
a line prints upon completion. The exit status of
background jobs is reported in a completion message.
On systems with job control, this option is turned
on automatically for interactive shells.
-n
Read commands and check them for syntax errors, but
do not execute them. Ignored for interactive shells.
-o
If no option name is supplied, the list of options
and their current settings are written to standard
output. When invoked with a ], the options are writ-
ten in a format that can be input again to the shell
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to restore the settings. This option can be repeated
to enable or disable multiple options.
The following argument can be one of the following
option names:
allexport
Same as -a.
bgnice
All background jobs are run at a lower priority.
This is the default mode.
braceexpand
Same as -B.
emacs
Puts you in an emacs style inline editor for
command entry.
errexit
Same as -e.
globstar
Same as -G.
gmacs
Puts you in a gmacs style inline editor for com-
mand entry.
ignoreeof
The shell does not exit on end-of-file. The com-
mand exit must be used.
keyword
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Same as -k.
markdirs
All directory names resulting from file name
generation have a trailing / appended.
monitor
Same as -m.
multiline
The built-in editors use multiple lines on the
screen for lines that are longer than the width
of the screen. This might not work for all ter-
minals.
noclobber
Same as -C.
noexec
Same as -n.
noglob
Same as -f.
nolog
Do not save function definitions in the history
file.
notify
Same as -b.
nounset
Same as -u.
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pipefail
A pipeline does not complete until all com-
ponents of the pipeline have completed, and the
return value is the value of the last non-zero
command to fail or zero if no command has
failed.
privileged
Same as -p.
showme
When enabled, simple commands or pipelines pre-
ceded by a a semicolon (;) is displayed as if
the xtrace option were enabled but is not exe-
cuted. Otherwise, the leading ; is ignored.
trackall
Same as -h.
verbose
Same as -v.
vi
Puts you in insert mode of a vi style inline
editor until you hit the escape character 033.
This puts you in control mode. A return sends
the line.
viraw
Each character is processed as it is typed in vi
mode.
xtrace
Same as -x.
If no option name is supplied, the current
options settings are printed.
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-p
Disables processing of the $HOME/.profile file and
uses the file /etc/suidprofile instead of the ENV
file. This mode is on whenever the effective uid
(gid) is not equal to the real uid (gid). Turning
this off causes the effective uid and gid to be set
to the real uid and gid.
-r
Enables the restricted shell. This option cannot be
unset once set.
-s
Sort the positional parameters lexicographically.
-t
Obsolete. Exit after reading and executing one com-
mand.
-u
Treat unset parameters as an error when substitut-
ing.
-v
Print shell input lines as they are read.
-x
Print commands and their arguments as they are exe-
cuted.
--
Do not change any of the options. This is useful in
setting $1 to a value beginning with -. If no argu-
ments follow this option then the positional parame-
ters are unset.
As an obsolete feature, if the first arg is - then the
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-x and -v options are turned off and the next arg is
treated as the first argument. Using ] rather than -
causes these options to be turned off. These options can
also be used upon invocation of the shell. The current
set of options can be found in $-. Unless -A is speci-
fied, the remaining arguments are positional parameters
and are assigned, in order, to $1 $2 .... If no argu-
ments are specified, then the names and values of all
variables are printed on the standard output.
]shift [n]
The positional parameters from $n]1 ... are renamed $1
..., the default n is 1. The parameter n can be any
arithmetic expression that evaluates to a non-negative
number less than or equal to $#.
sleep seconds
Suspends execution for the number of decimal seconds or
fractions of a second specified by seconds.
]trap -p [action] [sig] ...
The -p option causes the trap action associated with
each trap as specified by the arguments to be printed
with appropriate quoting. Otherwise, action is processed
as if it were an argument to eval when the shell
receives signal(s) sig. Each sig can be specified as a
number or as the name of the signal. Trap commands are
executed in order of signal number. Any attempt to set a
trap on a signal that was ignored on entry to the
current shell is ineffective. If action is omitted and
the first sig is a number, or if action is -, then the
trap(s) for each sig are reset to their original values.
If action is the null string then this signal is ignored
by the shell and by the commands it invokes. If sig is
ER then action is executed whenever a command has a
non-zero exit status. If sig is DEBUG then action is
executed before each command. The variable .sh.command
contains the contents of the current command line when
action is running. If sig is 0 or EXIT and the trap
statement is executed inside the body of a function
defined with the function name syntax, then the command
action is executed after the function completes. If sig
is 0 or EXIT for a trap set outside any function then
the command action is executed on exit from the shell.
If sig is KEYBD, then action is executed whenever a key
is read while in emacs, gmacs, or vi mode. The trap
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command with no arguments prints a list of commands
associated with each signal number.
true
Does nothing, and exits 0. Used with while for infinite
loops.
]typeset []AHflabnprtux ] [ ]EFLRZi[n] ] [ vname[=value ] ]
Sets attributes and values for shell variables and func-
tions. When invoked inside a function defined with the
function name syntax, a new instance of the variable
vname is created, and the variable's value and type are
restored when the function completes.
Using ] rather than - causes these options to be turned
off. If no vname arguments are specified, a list of
vnames (and optionally the values) of the variables is
printed. Using ] rather than - keeps the values from
being printed.) The -p option causes typeset followed by
the option letters to be printed before each name rather
than the names of the options. If any option other than
-p is specified, only those variables which have all of
the specified options are printed. Otherwise, the vnames
and attributes of all variables that have attributes are
printed.
The following list of attributes can be specified:
-a Declares vname to be an indexed array. This is
optional unless except for compound variable
assignments.
-A Declares vname to be an associative array. Sub-
scripts are strings rather than arithmetic expres-
sions.
-b The variable can hold any number of bytes of data.
The data can be text or binary. The value is
represented by the base64 encoding of the data. If
-Z is also specified, the size in bytes of the
data in the buffer is determined by the size asso-
ciated with the -Z. If the base64 string assigned
results in more data, it is truncated. Otherwise,
it is filled with bytes whose value is zero. The
printf format %B can be used to output the actual
data in this buffer instead of the base64 encoding
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of the data.
-E Declares vname to be a double precision floating
point number. If n is non-zero, it defines the
number of significant figures that are used when
expanding vname. Otherwise, ten significant fig-
ures is used.
-f The names refer to function names rather than
variable names. No assignments can be made and the
only other valid options are -t, -u, and -x. The
-t option turns on execution tracing for this
function. The -u option causes this function to be
marked undefined. The FPATH variable is searched
to find the function definition when the function
is referenced. If no options other than -f is
specified, then the function definition is
displayed on standard output. If ]f is specified,
then a line containing the function name followed
by a shell comment containing the line number and
path name of the file where this function was
defined, if any, is displayed.
The -i attribute cannot be specified with -f.
-F Declares vname to be a double precision floating
point number. If n is non-zero, it defines the
number of places after the decimal point that are
used when expanding vname. Otherwise ten places
after the decimal point is used.
-H This option provides UNIX to hostname file mapping
on non-UNIX machines.
-i Declares vname to be represented internally as
integer. The right hand side of an assignment is
evaluated as an arithmetic expression when assign-
ing to an integer. If n is non-zero, it defines
the output arithmetic base, otherwise the output
base is ten.
The -i attribute cannot be specified along with
-R, -L, -Z, or -f.
-l All uppercase characters are converted to lower-
case. The uppercase option, -u, is turned off.
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-L Left justify and remove leading blanks from value.
If n is non-zero, it defines the width of the
field, otherwise it is determined by the width of
the value of first assignment. When the variable
is assigned to, it is filled on the right with
blanks or truncated, if necessary, to fit into the
field. The -R option is turned off.
The -i attribute cannot be specified with -L.
-n Declares vname to be a reference to the variable
whose name is defined by the value of variable
vname. This is usually used to reference a vari-
able inside a function whose name has been passed
as an argument.
-R Right justify and fill with leading blanks. If n
is non-zero, it defines the width of the field,
otherwise it is determined by the width of the
value of first assignment. The field is left
filled with blanks or truncated from the end if
the variable is reassigned. The -L option is
turned off.
The -i attribute cannot be specified with -R.
-r The specified vnames are marked read-only and
these names cannot be changed by subsequent
assignment.
-t Tags the variables. Tags are user definable and
have no special meaning to the shell.
-u All lowercase characters are converted to upper-
case. The lowercase option, -l, is turned off.
-x The specified vnames are marked for automatic
export to the environment of subsequently-executed
commands. Variables whose names contain a . cannot
be exported.
-Z Right justify and fill with leading zeros if the
first non-blank character is a digit and the -L
option has not been set. Remove leading zeros if
the -L option is also set. If n is non-zero, it
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User Commands ksh93(1)
defines the width of the field, otherwise it is
determined by the width of the value of first
assignment.
The -i attribute cannot be specified with -Z.
ulimit [-HSacdfmnpstv] [ limit]
Set or display a resource limit. Many systems do not
support one or more of these limits. The limit for a
specified resource is set when limit is specified. The
value of limit can be a number in the unit specified
with each resource, or the value unlimited. When more
than one resource is specified, then the limit name and
unit is printed before the value.
If no option is specified, -f is assumed.
The following are the available resource limits:
-a Lists all of the current resource limits.
-c The number of 512-byte blocks on the size of core
dumps.
-d The number of Kbytes on the size of the data area.
-f The number of 512-byte blocks on files that can be
written by the current process or by child
processes (files of any size can be read).
-H Specifies a hard limit for the specified resource.
A hard limit cannot be increased once it is set.
If neither the -H nor -S option is specified, the
limit applies to both. The current resource limit
is printed when limit is omitted. In this case,
the soft limit is printed unless -H is specified.
-m The number of Kbytes on the size of physical
memory.
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-n The number of file descriptors plus 1.
-p The number of 512-byte blocks for pipe buffering.
-s The number of Kbytes on the size of the stack
area.
-S Specifies a soft limit for the specified resource.
A soft limit can be increased up to the value of
the hard limit.
If neither the -H nor -S option is specified, the
limit applies to both. The current resource limit
is printed when limit is omitted. In this case,
the soft limit is printed unless -H is specified.
-t The number of CPU seconds to be used by each pro-
cess.
-v The number of Kbytes for virtual memory.
umask [-S][mask]
The user file-creation mask is set to mask. mask can
either be an octal number or a symbolic value as
described in chmod(1).
If a symbolic value is specified, the new umask value is
the complement of the result of applying mask to the
complement of the previous umask value. If mask is omit-
ted, the current value of the mask is printed. The -S
option causes the mode to be printed as a symbolic
value. Otherwise, the mask is printed in octal.
See umask(2)
]unalias [-a] name
The aliases specified by the list of names are removed
from the alias list. The -a option causes all the
aliases to be unset.
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]unset [-fnv] vname
The variables specified by the list of vnames are unas-
signed, i.e., their values and attributes are erased.
Read-only variables cannot be unset. If the -f option is
set, then the names refer to function names. If the -v
option is set, then the names refer to variable names.
The -f option overrides -v. If -n is set and name is a
name reference, then name is unset rather than the vari-
able that it references. The default is equivalent to
-v. Unsetting LINENO, MAILCHECK, OPTARG, OPTIND, RANDOM,
SECONDS, TMOUT, and removes their special meaning even
if they are subsequently assigned to.
wait [job]
Wait for the specified job and report its termination
status. If job is not specified, then all currently
active child processes are waited for. The exit status
from this command is that of the last process waited for
if job is specified; otherwise it is zero. See Jobs for
a description of the format of job.
whence [-afpv] name ...
For each name, indicate how it would be interpreted if
used as a command name. The -v option produces a more
verbose report. The -f option skips the search for func-
tions. The -p option does a path search for name even if
name is an alias, a function, or a reserved word. The -a
option is similar to the -v option but causes all
interpretations of the specified name to be reported.
Invocation
If the shell is invoked by exec(2), and the first character
of argument zero ($0) is -, then the shell is assumed to be
a login shell and commands are read from /etc/profile and
then from either .profile in the current directory or
$HOME/.profile, if either file exists. Next, for interactive
shells, commands are read first from /etc/ksh.kshrc, and
then from the file named by performing parameter expansion,
command substitution, and arithmetic substitution on the
value of the environment variable ENV if the file exists. If
the -s option is not present and arg and a file by the name
of arg exists, then it reads and executes this script. Oth-
erwise, if the first arg does not contain a /, a path search
is performed on the first arg to determine the name of the
script to execute. The script arg must have execute permis-
sion and any setuid and setgid settings are ignored. If the
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script is not found on the path, arg is processed as if it
named a built-in command or function.
Commands are then read as described, and the following
options are interpreted by the shell when it is invoked:
-c If the -c option is present, then commands
are read from the first arg. Any remaining
arguments become positional parameters start-
ing at 0.
-D A list of all double quoted strings that are
preceded by a $ is printed on standard output
and the shell exits. This set of strings is
subject to language translation when the
locale is not C or POSIX. No commands are
executed.
-i If the -i option is present or if the shell
input and output are attached to a terminal
(as told by tcgetattr(3C), this shell is
interactive. In this case TERM is ignored (so
that kill 0 does not kill an interactive
shell) and INTR is caught and ignored (so
that wait is interruptible). In all cases,
QUIT is ignored by the shell.
-R filename The -R filename option is used to generate a
cross reference database that can be used by
a separate utility to find definitions and
references for variables and commands.
-r If the -r option is present, the shell is a
restricted shell.
-s If the -s option is present or if no argu-
ments remain, then commands are read from the
standard input. Shell output, except for the
output of the Special Commands listed, is
written to file descriptor 2.
The remaining options and arguments are described under the
set command. An optional - as the first argument is ignored.
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rksh93 Only
rksh93 is used to set up login names and execution environ-
ments whose capabilities are more controlled than those of
the standard shell.
The actions of rksh93 are identical to those of ksh93,
except that the following are disallowed:
o Unsetting the restricted option
o Changing directory. See cd(1).
o Setting or unsetting the value or attributes of
SHEL, ENV, FPATH, or PATH
o Specifying path or command names containing /,
o Redirecting output (>, >, <>, and >>).
o Adding or deleting built-in commands.
o Using command -p to invoke a command.
These restrictions are enforced after .profile and the ENV
files are interpreted.
When a command to be executed is found to be a shell pro-
cedure, rksh93 invokes ksh93 to execute it. Thus, it is pos-
sible to provide to the end-user shell procedures that have
access to the full power of the standard shell, while impos-
ing a limited menu of commands. This scheme assumes that the
end-user does not have write and execute permissions in the
same directory. The net effect of these rules is that the
writer of the .profile has complete control over user
actions, by performing guaranteed setup actions and leaving
the user in an appropriate directory (probably not the login
directory). The system administrator often sets up a direc-
tory of commands, for example, /usr/rbin, that can be safely
invoked by rksh.
USAGE
See largefile(5) for the description of the behavior of
ksh93 and rksh93 when encountering files greater than or
equal to 2 Gbyte ( 2^31 bytes).
EXIT STATUS
The following exit values are returned:
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User Commands ksh93(1)
non-zero
Returns non-zero when errors, such as syntax errors, are
detected by the shell.
If the shell is being used non-interactively, then exe-
cution of the shell file is abandoned unless the error
occurs inside a sub-shell in which case the sub-shell is
abandoned.
exit status of last command executed
Returns the exit status of the last command executed.
Run time errors detected by the shell are reported by
printing the command or function name and the error con-
dition. If the line number that the error occurred on is
greater than one, then the line number is also printed
in square brackets ([]) after the command or function
name.
See the ksh93 exit command for additional details.
FILES
/etc/profile
The system initialization file, executed for login
shells.
/etc/ksh.kshrc
The system wide startup file, executed for interactive
shells.
$HOME/.profile
The personal initialization file, executed for login
shells after /etc/profile.
$HOME/.kshrc
Default personal initialization file, executed after
/etc/ksh.kshrc, for interactive shells when ENV is not
set.
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/etc/suid-profile
Alternative initialization file, executed instead of the
personal initialization file when the real and effective
user or group id do not match.
/dev/null
NUL device.
AUTHORS
David Korn, dgk@research.att.com
ATRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
ATRIBUTE TYPE ATRIBUTE VALUE
Availability SUNWcsu
Interface Stability See below.
The scripting interface is Uncommitted. The environment
variables, .paths feature, and editing modes are Volatile.
SEE ALSO
cat(1), cd(1), chmod(1), cut(1), date(1), egrep(1), echo(1),
egrep(1), env(1), fgrep(1), grep(1), login(1), newgrp(1),
paste(1), printf(1), stty(1), test(1), umask(1), vi(1),
dup(2), exec(2), fork(2), ioctl(2), lseek(2), pathconf(2),
pipe(2), sysconf(3C), ulimit(2), umask(2),
rand(3C)tcgetattr(3C), wait(3C), a.out(4), profile(4),
attributes(5), environ(5), largefile(5), standards(5)
Bolsky, Morris I. and Korn, David G., The New KornShell Com-
mand and Programming Language, Prentice Hall, 1995.
POSIX-Part 2: Shell and Utilities, IE Std 1003.2-1992,
ISO/IEC 9945-2, IE, 1993.
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NOTES
If a command is executed, and then a command with the same
name is installed in a directory in the search path before
the directory where the original command was found, the
shell continues to exec the original command. Use the -t
option of the alias command to correct this situation.
Some very old shell scripts contain a caret (^) as a synonym
for the pipe character ().
Using the hist built-in command within a compound command
causes the whole command to disappear from the history file.
The built-in command . file reads the whole file before any
commands are executed. alias and unalias commands in the
file do not apply to any commands defined in the file.
Traps are not processed while a job is waiting for a fore-
ground process. Thus, a trap on CHLD is not executed until
the foreground job terminates.
It is a good idea to leave a space after the comma operator
in arithmetic expressions to prevent the comma from being
interpreted as the decimal point character in certain
locales.
There might be some restrictions on creating a .paths file
which is portable across other operating systems.
If the system supports the 64-bit instruction set,
/bin/ksh93 executes the 64-bit version of ksh93.
SunOS 5.11 Last change: 10 Feb 2009 89
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