Linux: pathmunge Command in Shell Script

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Q. I see pathmunge used in few scripts under Red Hat Enterprise Linux. Can you explain the use of pathmunge under RHEL / CentOS / Fedora Linux?

A. Red Hat, CentOS, and Fedora Linux has a pathmunge function defined in /etc/profile file. It will add the directories one by one to the default PATH for the root user.

pathmunge() function is defined in /etc/profile

pathmunge () {
        if ! echo $PATH | /bin/egrep -q "(^|:)$1($|:)" ; then
           if [ "$2" = "after" ] ; then
              PATH=$PATH:$1
           else
              PATH=$1:$PATH
           fi
        fi
}

Path manipulation done using pathmunge:

# Path manipulation
if [ "$EUID" = "0" ]; then
        pathmunge /sbin
        pathmunge /usr/sbin
        pathmunge /usr/local/sbin
fi

As long as you are using Red Hat or CentOS / Fedora Linux, you can use pathmunge. It is best to avoid this function if you need run a shell script on diffrent distributions. I recommend using export bash command for modifying PATH variable.

Posted by: Vivek Gite

The author is the creator of nixCraft and a seasoned sysadmin, DevOps engineer, and a trainer for the Linux operating system/Unix shell scripting. Get the latest tutorials on SysAdmin, Linux/Unix and open source topics via RSS/XML feed or weekly email newsletter.

4 comment

  1. It would have been nice if you explained what the script does! pathmunge adds something to the path only if it wasn’t already there. So if your path contains:
    /bin:/usr/bin
    pathmunge /usr/bin
    will do nothing.
    pathmunge /sbin
    will result in a path a path containing:
    /sbin:/bin:/usr/bin
    if instead, you’d said pathmunge /sbin after, the
    result would have been:
    /bin:/usr/bin:/sbin
    For portability, if you need something like this, just make it a part of your script.

    1. A voice from the future… :) thank you Patrick! I had just asked myself, ‘ok, but what does pathmunge do?’ and then I scrolled down and found your explanation.
      Much appreciated!

  2. I agree, you didn’t really answer much of the question at all. Also, it is not ‘best to avoid this function’ as you state. What is best is follow Patrick’s advice and just copy it directly into your own shell script.

  3. how to do this task ::Assume a directory contains many .mp3 files taken from albumes. If you are asked to sort them out into separate folders by artist. How would you do that?

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