This version uses Pipes, but is easier for the common user to grasp... instead of using sed or some other more complicated method, it uses the tr command Show Sample Output

Shorter version. Show Sample Output

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.

I often need to know of my directory in the PATH, which one DOES NOT exist. This command answers that question * This command uses only bash's built-in commands * The parentheses spawn a new sub shell to prevent the modification of the IFS (input field separator) variable in the current shell

Another way of doing it that's a bit clearer. I'm a fan of readable code.

This is useful for examining the path. Show Sample Output

i.e.: Useful if you add ~/bin to your $PATH and you want to override locations of previously ran commands and you don't want to log out and log back in to be able to use them.

Also searches for aliases and shell builtins Show Sample Output

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Here is another way to show the path, one directory per line. The command `tr` translates the colon into the new line, taking input from the $PATH variable Show Sample Output

Can be used to create path alias. From: https://www.cyberciti.biz/tips/bash-aliases-mac-centos-linux-unix.html. #9

Finds executable and existing directories in your path that can be useful if migrating a profile script to another system. This is faster and smaller than any other method due to using only bash builtin commands. See also: + http://www.commandlinefu.com/commands/view/743/list-all-execs-in-path-usefull-for-grepping-the-resulting-list + http://www.askapache.com/linux-unix/bash_profile-functions-advanced-shell.html Show Sample Output

quoteless Show Sample Output

Really helpfull when play with files having spaces an other bad name. Easy to store and access names and path in just a field while saving it in a file. This format (URL) is directly supported by nautilus and firefox (and other browsers) Show Sample Output

from: http://www.unix.com/shell-programming-and-scripting/28047-split-print-path.html Show Sample Output

I've seen a lot of overly complicated attempts at figuring out "where am I?" I think this is a part of the problem: type -a pwd force the use of the binary version of `pwd` instead of the built-in with "/bin/pwd -P" -P option provides an absolute path to the present working directory for the overly cautious type: (which pwd) -P Show Sample Output

OS: Debian based (or those that use dpkg) Equivalent to doing a dpkg -S on each file in $PATH, but way faster. May report files generated though postinstall scripts and such. For example . It will report /usr/bin/vim .. which is not not a file installed directly by dpkg, but a link generated by alternatives hooks

On RHEL, Fedora and CentOS systems, and maybe others, the sbin directories aren't in the user's $PATH. For those systems that use 'sudo', this can be inconvenient typing the full path all the time. As a result, you can easily take advantage of adding the sbin directories to your PATH by adding this simple line to you .zshrc.

Display the $PATH with one line per entry, in a pager. Show Sample Output

The wherepath function will search all the directories in your PATH and print a unique list of locations in the order they are first found in the PATH. (PATH often has redundant entries.) It will automatically use your 'ls' alias if you have one or you can hardcode your favorite 'ls' options in the function to get a long listing or color output for example. Alternatives: 'whereis' only searches certain fixed locations. 'which -a' searches all the directories in your path but prints duplicates. 'locate' is great but isn't installed everywhere (and it's often too verbose). Show Sample Output