User Commands readonly(1)
NAME
readonly - shell built-in function to protect the value of
the given variable from reassignment
SYNOPSIS
sh
readonly [name]...
ksh
**readonly [name [= value]...
**readonly -p
ksh93
]readonly [-p] [name [= value]...
DESCRIPTION
sh
The given names are marked readonly and the values of the
these names may not be changed by subsequent assignment. If
no arguments are given, a list of all readonly names is
printed.
ksh
The given names are marked readonly and these names cannot
be changed by subsequent assignment.
When -p is specified, readonly writes to the standard output
the names and values of all read-only variables, in the fol-
lowing format:
"readonly %s=%s\n", name, value
if name is set, and:
"readonly $s\n", name
if name is unset.
SunOS 5.11 Last change: 2 Nov 2007 1
User Commands readonly(1)
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 value and readonly
attribute-setting results in a shell execution environment
in which:
1. Variables with values set at the time they were
output do not have the readonly attribute set.
2. Variables that were unset at the time they were
output do not have a value at the time at which the
saved output is re-input 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
readonly sets the readonly attribute on each of the vari-
ables specified by name which prevents their values from
being changed. If =value is specified, the variable name is
set to value before the variable is made readonly.
If no names are specified then the names and values of all
readonly variables are written to standard output.
readonly 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.
-p Causes the output to be in a form of readonly commands
that can be used as input to the shell to recreate the
current set of readonly variables.
SunOS 5.11 Last change: 2 Nov 2007 2
User Commands readonly(1)
On this manual page, ksh93(1) commands that are preceded by
one or two ] symbols 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.
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.
EXIT STATUS
ksh93
The following exit values are returned:
0 Successful completion.
>0 An error occurred.
ATRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
ATRIBUTE TYPE ATRIBUTE VALUE
Availability SUNWcsu
SEE ALSO
ksh(1), ksh93(1), sh(1), typeset(1), attributes(5)
SunOS 5.11 Last change: 2 Nov 2007 3
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