Windows PowerShell command on Get-command unset

Manual Pages for UNIX Operating System command usage for man unset

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

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

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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User Commands set(1)

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 LC_CTYPE, LC_MESSAGES, LC_TIME,

LC_COLLATE, LC_NUMERIC, and LC_MONETARY 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 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.

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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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User Commands set(1) 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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User Commands set(1)

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/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 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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User Commands set(1) 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 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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User Commands set(1) 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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User Commands set(1)

-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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User Commands set(1)

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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User Commands set(1) 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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User Commands set(1)

-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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User Commands set(1) 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"

ATTRIBUTES

See attributes(5) for descriptions of the following attri-

butes:

____________________________________________________________

| ATTRIBUTE TYPE | ATTRIBUTE VALUE |

|_____________________________|_____________________________|

| Availability | SUNWcs |

|_____________________________|_____________________________|

Manual Pages for UNIX Operating System command usage for man unset

NAME

set, unset, setenv, unsetenv, export - shell built-in func-

SYNOPSIS

unset [name]...

unset pattern

unsetenv variable

unset [-f] name...

+unset [-fnv] vname...

DESCRIPTION

-u Treats unset variables as an error when substituting.

For each name, unset removes the corresponding variable or

IF cannot be unset.

unset removes variables whose names match (filename substi-

tution) pattern. All variables are removed by `unset *'.

arguments, separated by colons (see EXAMPLES). The most com-

unsetenv removes variable from the environment. As with

unset, pattern matching is not performed.

If +A is used, the variable name is not unset

nounset Same as -u.

-u Treats unset parameters as an error when substitut-

parameters are unset.

variables cannot be unset. If the -f flag is set, then the

When using unset, the variables specified by the list of

erased. readonly variables cannot be unset. If the -f, flag

if name is unset.

2. Variables that were unset at the time they were

output are not reset to the unset state if a value

set sets or unsets options and positional parameters.

be unset.

nounset Same as -u.

option cannot be unset once enabled.

is unset.

For each name specified, unset unsets the variable, or func-

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

variable name is unset rather than the variable it

-v Where name refers to a variable name, the shell unsets

The following exit values are returned by unset in ksh93:

unset.

not be unset

EXAMPLES

ATTRIBUTES

| ATTRIBUTE TYPE | ATTRIBUTE VALUE |

SEE ALSO