User Commands set(1)
NAME
set, unset, setenv, unsetenv, export - shell built-in func-
tions to determine the characteristics for environmental
variables of the current shell and its descendents
SYNOPSIS
sh
set [--aefhkntuvx [argument]...
unset [name]...
export [name]...
csh
set [var [= value]
set var [n] = word
unset pattern
setenv [VAR [word]
unsetenv variable
ksh
set []abCefhkmnopstuvx] []o option]... []A name]
[arg]...
unset [-f] name...
**export [name [=value]...
**export [-p]
ksh93
]set []abCefGhkmnoprstuvx] []o option]... []A vname]
[arg]...
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User Commands set(1)
]unset [-fnv] vname...
]export [-p] [name[=value]...
DESCRIPTION
sh
The set built-in command has the following options:
-- Does not change any of the flags. This option is use-
ful in setting $1 to -.
-a Marks variables which are modified or created for
export.
-e Exits immediately if a command exits with a non-zero
exit status.
-f Disables file name generation.
-h Locates and remembers function commands as functions
are defined. Function commands are normally located
when the function is executed.
-k All keyword arguments are placed in the environment
for a command, not just those that precede the command
name.
-n Reads commands but does not execute them.
-t Exits after reading and executing one command.
-u Treats unset variables as an error when substituting.
-v Prints shell input lines as they are read.
-x Prints commands and their arguments as they are exe-
cuted.
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Using ] rather than - causes these flags to be turned off.
These flags can also be used upon invocation of the shell.
The current set of flags can be found in $-. The remaining
arguments are positional parameters and are assigned, in
order, to $1, $2, .... If no arguments are specified the
values of all names are printed.
For each name, unset removes the corresponding variable or
function value. The variables PATH, PS1, PS2, MAILCHECK, and
IF cannot be unset.
With the export built-in, the specified names are marked for
automatic export to the environment of subsequently executed
commands. If no arguments are specified, variable names that
have been marked for export during the current shell's exe-
cution are listed. Function names are not exported.
csh
With no arguments, set displays the values of all shell
variables. Multiword values are displayed as a parenthesized
list. With the var argument alone, set assigns an empty
(null) value to the variable var. With arguments of the form
var = value set assigns value to var, where value is one of:
word A single word (or quoted string).
(wordlist) A space-separated list of words enclosed in
parentheses.
Values are command and filename expanded before being
assigned. The form set var[n]=word replaces the n'th word in
a multiword value with word.
unset removes variables whose names match (filename substi-
tution) pattern. All variables are removed by `unset *'.
With no arguments, setenv displays all environment vari-
ables. With the VAR argument, setenv sets the environment
variable VAR to an empty (null) value. (By convention,
environment variables are normally specified upper-case
names.) With both VAR and word arguments specified, setenv
sets VAR to word, which must be either a single word or a
quoted string. The PATH variable can take multiple word
arguments, separated by colons (see EXAMPLES). The most com-
monly used environment variables, USER, TERM, and PATH, are
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automatically imported to and exported from the csh vari-
ables user, term, and path. Use setenv if you need to change
these variables. In addition, the shell sets the PWD
environment variable from the csh variable cwd whenever the
latter changes.
The environment variables LCTYPE, LCMESAGES, LCTIME,
LCOLATE, LCNUMERIC, and LCMONETARY take immediate
effect when changed within the C shell. See environ(5) for
descriptions of these environment variables.
unsetenv removes variable from the environment. As with
unset, pattern matching is not performed.
ksh
The flags for the set built-in have meaning as follows:
-A Array assignment. Unsets the variable name and
assigns values sequentially from the list arg.
If ]A is used, the variable name is not unset
first.
-a All subsequent variables that are defined are
automatically exported.
-b Causes the shell to notify the user asynchro-
nously of background job completions.
-C Prevents existing files from being overwritten
by the shell's > redirection operator. The >
redirection operator overrides this noclobber
option for an individual file.
-e If a command has a non-zero exit status, exe-
cutes the ER trap, if set, and exits. This
mode is disabled while reading profiles.
-f Disables file name generation.
-h Each command becomes a tracked alias when first
encountered.
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-k 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 com-
pletion message. On systems with job control,
this flag is turned on automatically for
interactive shells.
-n Reads commands and checks them for syntax
errors, but does not execute them. Ignored for
interactive shells.
]o Writes the current option stettings to standard
output in a format that is suitable for reinput
to the shell as commands that achieve the same
option settings.
-o option The option argument can be one of the following
option names:
allexport Same as -a.
errexit Same as -e.
bgnice All background jobs are run at a
lower priority. This is the
default mode. emacs Puts you in
an emacs style in-line editor for
command entry.
gmacs Puts you in a gmacs style in-line
editor for command entry.
ignoreeof The shell does not exit on end-
of-file. The command exit must be
used.
keyword Same as -k.
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markdirs All directory names resulting
from file name generation have a
trailing / appended.
monitor Same as -m.
noclobber Prevents redirection operator >
from truncating existing files.
Requires the > operator to trun-
cate a file when turned on. Same
as -C.
noexec Same as -n.
noglob Same as -f.
nolog Does not save function defini-
tions in history file.
notify Same as -b.
nounset Same as -u.
privileged Same as -p.
verbose Same as -v.
trackall Same as -h.
vi Puts you in insert mode of a vi
style in-line editor until you
hit 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.
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xtrace Same as -x.
If no option name is supplied then the current option set-
tings are printed.
-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 is
not equal to the real uid, or when the effective gid
is not equal to the real gid. Turning this off
causes the effective uid and gid to be set to the
real uid and gid.
-s Sorts the positional parameters lexicographically.
-t Exits after reading and executing one command.
-u Treats unset parameters as an error when substitut-
ing.
-v Prints shell input lines as they are read.
-x Prints commands and their arguments as they are exe-
cuted.
- Turns off -x and -v flags and stops examining argu-
ments for flags.
- Does not change any of the flags. This option is
useful in setting $1 to a value beginning with -. If
no arguments follow this flag then the positional
parameters are unset.
Using ] rather than - causes these flags to be turned off.
These flags can also be used upon invocation of the shell.
The current set of flags can be found in $-. Unless -A is
specified, the remaining arguments are positional parameters
and are assigned, in order, to $1 $2 .... If no arguments
are specified then the names and values of all variables are
printed on the standard output.
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The variables specified by the list of names are unassigned,
that is, their values and attributes are erased. readonly
variables cannot be unset. If the -f flag is set, then the
names refer to function names. Unsetting ERNO, LINENO,
MAILCHECK, OPTARG, OPTIND, RANDOM, SECONDS, TMOUT, and
removes their special meaning even if they are subsequently
assigned.
When using unset, the variables specified by the list of
names are unassigned, i.e., their values and attributes are
erased. readonly variables cannot be unset. If the -f, flag
is set, then the names refer to function names. Unsetting
ERNO, LINENO, MAILCHECK, OPTARG, OPTIND, RANDOM, SECONDS,
TMOUT, and removes their special meaning even if they are
subsequently assigned.
With the export built-in, the specified names are marked for
automatic export to the environment of subsequently-executed
commands.
When -p is specified, export writes to the standard output
the names and values of all exported variables in the fol-
lowing format:
"export %s=%s\n", name, value
if name is set, and:
"export %s\n", name
if name is unset.
The shell formats the output, including the proper use of
quoting, so that it is suitable for reinput to the shell as
commands that achieve the same exporting results, except for
the following:
1. Read-only variables with values cannot be reset.
2. Variables that were unset at the time they were
output are not reset to the unset state if a value
is assigned to the variable between the time the
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state was saved and the time at which the saved
output is reinput to the shell.
On this manual page, ksh(1) commands that are preceded by
one or two * (asterisks) are treated specially in the fol-
lowing ways:
1. Variable assignment lists preceding the command
remain in effect when the command completes.
2. I/O redirections are processed after variable
assignments.
3. Errors cause a script that contains them to abort.
4. Words, following a command preceded by ** that are
in the format of a variable assignment, are
expanded with the same rules as a variable assign-
ment. This means that tilde substitution is per-
formed after the = sign and word splitting and file
name generation are not performed.
ksh93
set sets or unsets options and positional parameters.
Options that are specified with a - cause the options to be
set. Options that are specified with a ] cause the option to
be unset.
set without any options or arguments displays the names and
values of all shell variables in the order of the collation
sequence in the current locale. The values are quoted so
that they are suitable for input again to the shell.
If no arguments are specified, not even the end of options
argument --, the positional parameters are unchanged. Other-
wise, unless the -A option has been specified, the posi-
tional parameters are replaced by the list of arguments. A
first argument of -- is ignored when setting positional
parameters.
For backwards compatibility, a set command without any
options specified, whose first argument is - turns off the
-v and -x options. If any additional arguments are speci-
fied, they replace the positional parameters.
The options for set in ksh93 are:
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-a Set the export attribute for each variable
whose name does not contain a . that you
assign a value in the current shell environ-
ment.
-A name Assign the arguments sequentially to the
array named by name starting at subscript 0
rather than to the positional parameters.
-b The shell writes a message to standard error
as soon it detects that a background job com-
pletes rather than waiting until the next
prompt.
-B Enable {...} group expansion. On by default.
-C Prevents existing regular files from being
overwritten using the > redirection operator.
The > redirection overrides this noclobber
option.
-e A simple command that has a non-zero exit
status causes the shell to exit unless the
simple command is:
o contained in an && or list
o the command immediately following
if, while, or until
o contained in the pipeline following
!
-f Pathname expansion is disabled.
-G Causes ** by itself to also match all sub-
directories during pathname expansion.
-h Obsolete. Causes each command whose name has
the syntax of an alias to become a tracked
alias when it is first encountered.
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-H Enable !-style history expansion similar to
csh.
-k This is obsolete. All arguments of the form
name=value are removed and placed in the
variable assignment list for the command.
Ordinarily, variable assignments must precede
command arguments.
-m When enabled, the shell runs background jobs
in a separate process group and displays a
line upon completion. This mode is enabled by
default for interactive shells on systems
that support job control.
-n The shell reads commands and checks for syn-
tax errors, but does not execute the command.
Usually specified on command invocation.
-o [option] If option is not specified, the list of
options and their current settings is written
to standard output. When invoked with a ] the
options are written in a format that can be
input again to the shell to restore the set-
tings. This option can be repeated to enable
or disable multiple options.
The value of option must be one of the fol-
lowing:
allexport Same as -a.
bgnice All background jobs are run at
lower priorities.
braceexpand Same as -B.
emacs Enables or disables emacs
editing mode.
errexit Same as -e.
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globstar Equivalent to -G.
gmacs Enables or disables gmacs.
gmacs editing mode is the same
as emacs editing mode, except
for the handling of CTRL-T.
histexpand Same as -H.
ignoreeof The interactive shell does not
exit on end-of-file.
keyword Same as -k.
markdirs All directory names resulting
from file name generation have
a trailing / appended.
monitor Same as -m.
multiline Use multiple lines when edit-
ing lines that are longer than
the window width.
noclobber Same as -C.
noexec Same as -n.
noglob Same as -f.
nolog This has no effect. It is pro-
vided for backward compatibil-
ity.
notify Same as -b.
nounset Same as -u.
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pipefail A pipeline does not complete
until all components of the
pipeline have completed, and
the exit status of the pipe-
line is the value of the last
command to exit with non-zero
exit status, or is zero if all
commands return zero exit
status.
privileged Same as -p.
showme Simple commands preceded by a
; are traced as if -x were
enabled but not executed.
trackall Same as -h.
verbose Same as -v.
vi Enables or disables vi editing
mode.
viraw Does not use canonical input
mode when using vi edit mode
xtrace Same as -x.
-p Privileged mode. Disabling -p sets the effec-
tive user id to the real user id, and the
effective group id to the real group id. Ena-
bling -p restores the effective user and
group ids to their values when the shell was
invoked. The -p option is on whenever the
real and effective user id is not equal or
the real and effective group id is not equal.
User profiles are not processed when -p is
enabled.
-r Restricted. Enables restricted shell. This
option cannot be unset once enabled.
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-s Sort the positional parameters
-t Obsolete. The shell reads one command and
then exits.
-u If enabled, the shell displays an error mes-
sage when it tries to expand a variable that
is unset.
-v Verbose. The shell displays its input onto
standard error as it reads it.
-x Execution trace. The shell displays each com-
mand after all expansion and before execution
preceded by the expanded value of the PS4
parameter.
The following exit values are returned by set in ksh93:
0 Successful completion.
>0 An error occurred.
For each name specified, unset unsets the variable, or func-
tion if -f is specified, from the current shell execution
environment. Read-only variables cannot be unset.
The options for unset in ksh93 are:
-f Where name refers to a function name, the shell unsets
the function definition.
-n If name refers to variable that is a reference, the
variable name is unset rather than the variable it
references. Otherwise, this option is equivalent to
the -v option.
-v Where name refers to a variable name, the shell unsets
it and removes it from the environment. This is the
default behavior.
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The following exit values are returned by unset in ksh93:
0 Successful completion. All names were successfully
unset.
>0 An error occurred, or one or more name operands could
not be unset
export sets the export attribute on each of the variables
specified by name which causes them to be in the environment
of subsequently executed commands. If =value is specified,
the variable name is set to value.
If no name is specified, the names and values of all
exported variables are written to standard output.
export is built-in to the shell as a declaration command so
that field splitting and pathname expansion are not per-
formed on the arguments. Tilde expansion occurs on value.
The options for export in ksh93 are:
-p Causes the output to be in the form of export commands
that can be used as input to the shell to recreate the
current exports.
The following exit values are returned by export in ksh93:
0 Successful completion.
>0 An error occurred.
On this manual page, ksh93(1) commands that are preceded by
one or two ] are treated specially in the following ways:
1. Variable assignment lists preceding the command
remain in effect when the command completes.
2. I/O redirections are processed after variable
assignments.
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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 assign-
ment. This means that tilde substitution is per-
formed after the = sign and field splitting and
file name generation are not performed.
EXAMPLES
csh
The following example sets the PATH variable to search for
files in the /bin, /usr/bin, /usr/sbin, and /usr/ucb/bin
directories, in that order:
setenv PATH "/bin:/usr/bin:/usr/sbin:usr/ucb/bin"
ATRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
ATRIBUTE TYPE ATRIBUTE VALUE
Availability SUNWcsu
SEE ALSO
csh(1), ksh(1), ksh93(1), read(1), sh(1), typeset(1), attri-
butes(5), environ(5)
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