unset

This article is about Unix command. For the town in Hedmark, see Unset, Norway. For the novelist, see Sigrid Undset.

unset is a builtin Unix shell command implemented by both the Bourne shell family of shells (sh, ksh, bash, etc.) and the C shell family of shells (csh, tcsh, etc.). It unsets a shell variable, removing it from memory and the shell's exported environment. It is implemented as a shell builtin, because it directly manipulates the internals of the shell.

Read-only shell variables cannot be unset. If one tries to unset a read-only variable, the unset command will print an error message and return a non-zero exit code. For more information on read-only variables, see readonly.

External links

broken link: *unset: unset values and attributes of variables and functions – Commands & Utilities Reference, The Single UNIX® Specification, Issue 7 from The Open Group

v t e Unix command-line interface programs and shell builtins

File system	cat cd chmod chown chgrp cksum cmp cp dd du df file fsck fuser ln ls lsattr lsof mkdir mount mv pax pwd rm rmdir size split tee touch type umask

Processes	at bg chroot cron fg kill killall nice pgrep pidof pkill ps pstree time top

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Text processing	awk banner basename comm csplit cut dirname ed ex fmt fold head iconv join less more paste sed sort spell strings tail tr uniq vi wc xargs

Shell builtins	alias echo expr printf sleep test true and false unset wait yes

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Last modified on 16 March 2013, at 22:02

unset

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