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  • Version 2.20
  • Version 2.19
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    Manual page

    
    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 explic-
               ity 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.
           --version,-v,-V
               Print version information on standard output then exit success-
               fully.
    
           --help
               Print usage information on standard output then exit successfully.
    
    RETURN VALUE
           Which returns the number of failed arguments, or -1 when no `program-
           name' 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 
    
    SEE ALSO
           bash(1)
    
    
    
                                                                          WHICH(1)
    

    Examples

    >#! /bin/bash
    >umask 022
    >export PATH=".:~/bin:/bin:/usr/bin"
    >export HOME=`(cd ~; pwd)`
    >alias which="$HOME/c/which/which"
    
    >touch cat; chmod 755 cat; pwd
    /home/carlo/c/which
    >alias
    
    >which
    Usage: which [options] [--] COMMAND [...]
    Write the full path of COMMAND(s) to standard output.
    
      --version, -[vV] Print version and exit successfully.
      --help,          Print this help and exit successfully.
      --skip-dot       Skip directories in PATH that start with a dot.
      --skip-tilde     Skip directories in PATH that start with a tilde.
      --show-dot       Don't expand a dot to current directory in output.
      --show-tilde     Output a tilde for HOME directory for non-root.
      --tty-only       Stop processing options on the right if not on tty.
      --all, -a        Print all matches in PATH, not just the first
      --read-alias, -i Read list of aliases from stdin.
      --skip-alias     Ignore option --read-alias; don't read stdin.
      --read-functions Read shell functions from stdin.
      --skip-functions Ignore option --read-functions; don't read stdin.
    
    Recommended use is to write the output of (alias; declare -f) to standard
    input, so that which can show aliases and shell functions. See which(1) for
    examples.
    
    If the options --read-alias and/or --read-functions are specified then the
    output can be a full alias or function definition, optionally followed by
    the full path of each command used inside of those.
    
    Report bugs to .
    
    >which --version
    GNU which v2.20, Copyright (C) 1999 - 2008 Carlo Wood.
    GNU which comes with ABSOLUTELY NO WARRANTY;
    This program is free software; your freedom to use, change
    and distribute this program is protected by the GPL.
    
    >which -- --version
    which: no --version in (.:~/bin:/bin:/usr/bin)
    
    >which cat
    /home/carlo/c/which/cat
    
    >which --show-tilde cat
    ~/c/which/cat
    
    >which --show-dot cat
    ./cat
    
    >which --show-tilde --show-dot cat
    ./cat
    
    >which --skip-dot cat
    /bin/cat
    
    >(cd /bin; which cat)
    /bin/cat
    
    >(cd /bin; which --show-dot cat)
    ./cat
    
    >(cd /bin; PATH=".:/bin:/usr/bin" which --show-dot cat)
    ./cat
    
    >(cd /bin; PATH="/bin:.:/usr/bin" which --show-dot cat)
    /bin/cat
    
    >(cd /bin; PATH=".:/bin:/usr/bin" which --skip-dot --show-dot cat)
    /bin/cat
    
    >which ls
    /bin/ls
    
    >which xxx
    which: no xxx in (.:~/bin:/bin:/usr/bin)
    
    >which ./ls
    which: no ls in (.)
    
    >(cd /; which bin/ls)
    /bin/ls
    
    >(cd /; which --show-dot bin/ls)
    ./bin/ls
    
    >(cd /; which --show-dot /bin/ls)
    /bin/ls
    
    >(cd /; which --show-dot bin/xxx)
    which: no xxx in (./bin)
    
    >(cd /; which --show-dot /bin/xxx)
    which: no xxx in (/bin)
    
    >which --all cat
    /home/carlo/c/which/cat
    /bin/cat
    
    >touch xxx
    >which ./xxx
    which: no xxx in (.)
    
    >chmod 711 xxx
    >which ./xxx
    /home/carlo/c/which/xxx
    
    >chmod 655 cat
    >which cat
    /bin/cat
    
    >su
    >chown root cat
    >exit
    >which cat
    /home/carlo/c/which/cat
    
    >su
    >chmod 545 cat
    >exit
    >which cat
    /bin/cat
    
    >su
    >chgrp bin cat
    >exit
    >which cat
    /home/carlo/c/which/cat
    
    >su
    >chmod 541 cat
    >exit
    >which cat
    /home/carlo/c/which/cat
    >su
    >rm -f cat
    
    >chown root xxx
    >exit
    >which ./xxx
    /home/carlo/c/which/xxx
    
    >su
    >chmod 700 xxx
    >exit
    >which ./xxx
    which: no xxx in (.)
    
    >id
    uid=1000(carlo) gid=1000(carlo) groups=20(dialout),24(cdrom),25(floppy),29(audio),44(video),46(plugdev),106(netdev),109(powerdev),115(kvm),1000(carlo)
    >ls -l xxx
    -rwx------ 1 root carlo 0 2008-08-06 17:22 xxx
    >su
    >chmod 750 xxx
    >chgrp carlo xxx
    >exit
    >which ./xxx
    /home/carlo/c/which/xxx
    
    >su
    >chgrp bin xxx
    >exit
    >which ./xxx
    which: no xxx in (.)
    
    >alias which='alias | which --tty-only --read-alias --show-tilde --show-dot'
    >alias test1='test1'
    >alias test2='echo "test2" | cat | sort'
    >alias test3='  echo "test2"|cat&sort'
    >alias test4='	ls &&sort ||/usr/bin/which || exit'
    
    >which which
    alias which='alias | which --tty-only --read-alias --show-tilde --show-dot'
    	~/c/which/which
    >which test1
    alias test1='test1'
    >which test2
    alias test2='echo test2 | cat | sort'
    	/bin/echo
    	/bin/cat
    	/usr/bin/sort
    >which test3
    alias test3='  echo test2|cat&sort'
    	/bin/echo
    	/bin/cat
    	/usr/bin/sort
    >which test4
    alias test4='	ls &&sort ||/usr/bin/which || exit'
    	/bin/ls
    	/usr/bin/sort
    	/usr/bin/which