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`which': Show the full path of commands
***************************************
The `which' program shows the full path of (shell) commands.
This file documents `which' version 2.20, updated 16 January 2008.
* Menu:
* Which Program:: The `which' Program
* Invoking Which:: How to invoke `which'
* Option Summary:: Overview of commandline options
* Return Value:: The return value of `which'
* Example:: Examples of invokation
* Bugs:: Known bugs
* See Also:: Related UNIX commands
* Index:: Index
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1 The `which' Program
*********************
`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
executed 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)'.
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2 Invoking `which'
******************
The synopsis to invoke `which' is
which [options] [--] programname [...]
* Menu:
* Option Summary:: Option summary
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3 Option Summary
****************
`--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
function 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.
File: which.info, Node: Return Value, Next: Example, Prev: Option Summary, Up: Top
4 Return Value
**************
`Which' returns the number of failed arguments, or -1 when no
`programname' was given.
File: which.info, Node: Example, Next: Bugs, Prev: Return Value, Up: Top
5 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
File: which.info, Node: Bugs, Next: See Also, Prev: Example, Up: Top
6 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.
File: which.info, Node: See Also, Next: Index, Prev: Bugs, Up: Top
7 See Also
**********
`bash(1)'
File: which.info, Node: Index, Prev: See Also, Up: Top
Index
*****
[index]
* Menu:
* --all: Option Summary. (line 6)
* --help: Option Summary. (line 57)
* --read-alias: Option Summary. (line 10)
* --read-functions: Option Summary. (line 22)
* --show-dot: Option Summary. (line 41)
* --show-tilde: Option Summary. (line 46)
* --skip-alias: Option Summary. (line 17)
* --skip-dot: Option Summary. (line 34)
* --skip-functions: Option Summary. (line 29)
* --skip-tilde: Option Summary. (line 37)
* --tty-only: Option Summary. (line 50)
* --version: Option Summary. (line 53)
* -a: Option Summary. (line 6)
* -i: Option Summary. (line 10)
* -V: Option Summary. (line 53)
* -v: Option Summary. (line 53)
* aliases, handling of: Example. (line 6)
* Bugs, known: Bugs. (line 6)
* Command line Options: Option Summary. (line 6)
* Description of which: Which Program. (line 6)
* Examples: Example. (line 6)
* Invoking which: Invoking Which. (line 6)
* Options, command line: Option Summary. (line 6)
* Overview of command line options: Option Summary. (line 6)
* Return value of which: Return Value. (line 6)
* Synopsis: Invoking Which. (line 6)
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