The set built-in command has the following options:
--
Does not change any of the flags. This option is useful
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
executed.
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 execution are listed.
Function names are not exported.
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
substitution) pattern. All variables are removed by `unset
*'.
With no arguments, setenv displays all environment
variables. 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 commonly used environment
variables, USER, TERM, and PATH, are automatically
imported to and exported from the csh variables 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 LC_CTYPE, LC_MESSAGES,
LC_TIME, LC_COLLATE, LC_NUMERIC, and LC_MONETARY
take immediate effect when changed within the C shell. See environ(7)
for descriptions of these environment variables.
unsetenv removes variable from the environment. As
with unset, pattern matching is not performed.
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 asynchronously 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, executes the
ERR 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.
-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 completion 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 settings 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.
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 truncate a file when
turned on. Same as -C.
noexec
Same as -n.
noglob
Same as -f.
nolog
Does not save function definitions 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.
xtrace
Same as -x.
If no option name is supplied then the current option settings are
printed.
-p
Disables processing of the $HOME/.profile file and
uses the file /etc/suid_profile 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
substituting.
-v
Prints shell input lines as they are read.
-x
Prints commands and their arguments as they are
executed.
−
Turns off -x and -v flags and stops
examining arguments 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.
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 ERRNO, 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 ERRNO,
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 following
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 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 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.
- 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 word splitting and file name generation are not
performed.
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. Otherwise,
unless the -A option has been specified, the positional 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 specified, they
replace the positional parameters.
The options for set in ksh93 are:
-a
Set the export attribute for each variable whose name
does not contain a . that you assign a value in the current shell
environment.
-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 completes 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.
-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 syntax 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 settings. This option can be repeated to enable or disable
multiple options.
The value of option must be one of the following:
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.
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 editing 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 provided for backward
compatibility.
notify
Same as -b.
nounset
Same as -u.
pipefail
A pipeline does not complete until all components of the
pipeline have completed, and the exit status of the pipeline 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 effective
user id to the real user id, and the effective group id to the real group id.
Enabling -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.
-s
Sort the positional parameters
-t
Obsolete. The shell reads one command and then
exits.
-u
If enabled, the shell displays an error message 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 command 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
function 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.
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 performed 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.
- 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 generation are not
performed.