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Add directory to $PATH if it's not already there

Terminal - Add directory to $PATH if it's not already there
if [[ ":$PATH:" != *":$dir:"* ]]; then PATH=${PATH}:$dir; fi
2013-08-11 01:19:13
User: dmmst19
9
Add directory to $PATH if it's not already there

Sometimes in a script you want to make sure that a directory is in the path, and add it in if it's not already there. In this example, $dir contains the new directory you want to add to the path if it's not already present.

There are multiple ways to do this, but this one is a nice clean shell-internal approach. I based it on http://stackoverflow.com/a/1397020.

You can also do it using tr to separate the path into lines and grep -x to look for exact matches, like this:

if ! $(echo "$PATH" | tr ":" "\n" | grep -qx "$dir") ; then PATH=$PATH:$dir ; fi

which I got from http://stackoverflow.com/a/5048977.

Or replace the "echo | tr" part with a shell parameter expansion, like

if ! $(echo "${PATH//:/$'\n'}" | grep -qx "$dir") ; then PATH=$PATH:$dir ; fi

which I got from http://www.commandlinefu.com/commands/view/3209/.

There are also other more regex-y ways to do it, but I find the ones listed here easiest to follow.

Note some of this is specific to the bash shell.

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Terminal - Alternatives

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