Export path in .profile on mac

Question

I can't believe there isn't any tutorials about this after googling. Can someone point me a direction or explain what these lines and variables mean in .profile on mac? How can someone configure them?

export PATH=/opt/local/bin:/opt/local/sbin:$PATH # Finished adapting your PATH environment variable for use with MacPorts. #export PATH="/usr/local/bin:/usr/local/sbin:/usr/local/mysql/bin:$PATH" export PATH=$PATH:/usr/local/mysql/bin #export PATH="/usr/local/bin:/usr/local/sbin:/usr/local/mysql/bin:$PATH" #export PATH=/Applications/MAMP/Library/bin:/Applications/MAMP/bin/php5/bin:/Applications/MAMP/htdocs/cake/cake/console:/opt/local/bin:/opt/local/sbin:$PATH export PATH=/android-sdks/platform-tools:~/android-sdks/tools:$PATH export PATH=/Users/android-sdks/platform-tools:/Users/android-sdks/tools:$PATH 

Answer 1

Any line starting with # is a comment. PATH= sets the value of the PATH variable, $PATH expands to the current value, and the export at the beginning makes the value available to programs that you run from the terminal.

Let's assume that the initial value of PATH is /usr/bin:/bin.

export PATH=/opt/local/bin:/opt/local/sbin:$PATH 

Replace $PATH with the previous value of $PATH. So the above sets PATH to

/opt/local/bin:/opt/local/sbin:/usr/bin:/bin 

Moving forward,

export PATH=$PATH:/usr/local/mysql/bin 

Again, replace $PATH with the previous value:

/opt/local/bin:/opt/local/sbin:/usr/bin:/bin:/usr/local/mysql/bin 

After

export PATH=/android-sdks/platform-tools:~/android-sdks/tools:$PATH 

we have

/android-sdks/platform-tools:~/android-sdks/tools:/opt/local/bin:/opt/local/sbin:/usr/bin:/bin:/usr/local/mysql/bin 

(The ~ is a special token that will be replaced with the path to your home directory, but you should get the picture.)

And finally, after

export PATH=/Users/android-sdks/platform-tools:/Users/android-sdks/tools:$PATH 

we get

/Users/android-sdks/platform-tools:/Users/android-sdks/tools:/android-sdks/platform-tools:~/android-sdks/tools:/opt/local/bin:/opt/local/sbin:/usr/bin:/bin:/usr/local/mysql/bin 

PATH is used to find commands that you enter on the command line. So if you type foo, the shell will look for the names below, in the order specified:

/Users/android-sdks/platform-tools/foo /Users/android-sdks/tools/foo /android-sdks/platform-tools/foo ~/android-sdks/tools/foo /opt/local/bin/foo /opt/local/sbin/foo /usr/bin/foo /bin/foo /usr/local/mysql/bin/foo 

To see the current value of PATH, run

echo $PATH 

Should you add new directories to the beginning of PATH, or to the end? It doesn't always matter, but sometimes it does. It depends on which locations you want the system to check first.

You should add to the beginning if the goal is to search other directories before looking in the default ones. For example, git is a utility used to manage source code. If I wanted to install a newer version of git in ~/git and use that by default, I'd do:

export PATH=~/git/bin:$PATH 

This means that ~/git/bin/git would override /opt/local/bin/git.

On the other hand I might prefer to have the administrator install git system-wide. If I want to use my local copy only until the administrator makes it available for everyone, then this makes more sense:

export PATH=$PATH:~/git/bin 

In this case ~/git/bin/git would only be used if /opt/local/bin/git didn't already exist since /opt/local/bin is earlier in the path.

A lot of commands won't exist in more than one place. For example you might write my-backup-script and put it on an Apple Time Capsule at /Volumes/Capsule/scripts. It's not likely that there would be a command called my-backup-script in any other location to conflict. So either of the following commands would let you type my-backup-script and run the right script:

export PATH=/Volumes/Capsule/scripts:$PATH 

or

export PATH=$PATH:/Volumes/Capsule/scripts 

Is one better? My advice would be to do the latter. Remember that system will need to search the directories in $PATH, in order, for every command that it needs to find. Most commands will be on the local system, so it makes the most sense to put slower network storage at the end of the path.

Answer 2

From the man page, export simply sets an environment variable.

The PATH environment variable tells your Mac where to look for commands that you type on the command line, in the order that it should look. It is a list of paths, delimited by a colon.

The value $PATH is the current value of the PATH environment variable.

Thus, a line like

export PATH=/foo:$PATH 

prepends /foo to the PATH

and

export PATH=$PATH:/foo 

appends /foo to the PATH