WHICH(1) General Commands Manual WHICH(1)NAME
which - locate a command
SYNOPSIS
which [-a] filename ...
DESCRIPTION
which returns the pathnames of the files (or links) which would be executed in the current environment, had its arguments been given as
commands in a strictly POSIX-conformant shell. It does this by searching the PATH for executable files matching the names of the argu-
ments. It does not follow symbolic links.
OPTIONS -a print all matching pathnames of each argument
EXIT STATUS
0 if all specified commands are found and executable
1 if one or more specified commands is nonexistent or not executable
2 if an invalid option is specified
Debian 1 May 2009 WHICH(1)
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WHICH(1) General Commands Manual WHICH(1)NAME
which - shows the full path of (shell) commands.
SYNOPSIS
which [options] [--] programname [...]
DESCRIPTION
Which takes one or more arguments. For each of its arguments it prints to stdout the full path of the executables that would have been exe-
cuted when this argument had been entered at the shell prompt. It does this by searching for an executable or script in the directories
listed in the environment variable PATH using the same algorithm as bash(1).
This man page is generated from the file which.texinfo.
OPTIONS --all, -a
Print all matching executables in PATH, not just the first.
--read-alias, -i
Read aliases from stdin, reporting matching ones on stdout. This is useful in combination with using an alias for which itself. For
example
alias which='alias | which -i'.
--skip-alias
Ignore option `--read-alias', if any. This is useful to explicity search for normal binaries, while using the `--read-alias' option in
an alias or function for which.
--read-functions
Read shell function definitions from stdin, reporting matching ones on stdout. This is useful in combination with using a shell func-
tion for which itself. For example:
which() { declare -f | which --read-functions $@ }
export -f which
--skip-functions
Ignore option `--read-functions', if any. This is useful to explicity search for normal binaries, while using the `--read-functions'
option in an alias or function for which.
--skip-dot
Skip directories in PATH that start with a dot.
--skip-tilde
Skip directories in PATH that start with a tilde and executables which reside in the HOME directory.
--show-dot
If a directory in PATH starts with a dot and a matching executable was found for that path, then print "./programname" rather than the
full path.
--show-tilde
Output a tilde when a directory matches the HOME directory. This option is ignored when which is invoked as root.
--tty-only
Stop processing options on the right if not on tty.
--version,-v,-V
Print version information on standard output then exit successfully.
--help
Print usage information on standard output then exit successfully.
RETURN VALUE
Which returns the number of failed arguments, or -1 when no `programname' was given.
EXAMPLE
The recommended way to use this utility is by adding an alias (C shell) or shell function (Bourne shell) for which like the following:
[ba]sh:
which ()
{
(alias; declare -f) | /usr/bin/which --tty-only --read-alias --read-functions --show-tilde --show-dot $@
}
export -f which
[t]csh:
alias which 'alias | /usr/bin/which --tty-only --read-alias --show-dot --show-tilde'
This will print the readable ~/ and ./ when starting which from your prompt, while still printing the full path when used from a script:
> which q2
~/bin/q2
> echo `which q2`
/home/carlo/bin/q2
BUGS
The HOME directory is determined by looking for the HOME environment variable, which aborts when this variable doesn't exist. Which will
consider two equivalent directories to be different when one of them contains a path with a symbolic link.
AUTHOR
Carlo Wood <carlo@gnu.org>
SEE ALSO bash(1)WHICH(1)