The PATH Environment Variable

Adding Executable Program Commands to the PATH variable

Understanding the PATH variable and adding commands to use in your terminal

PATH variable

Your computer (Mac or Linux, or a Unix-based system) has an environment variable called PATH, which contains a set of executable program directories that contain the executable programs.

Executable programs are basically the commands you can use in the shell.

These include the essential boot-stage or early-stage required binaries as well as other general system-wide commands.

As per the Filesystem Hierarchy Standard (FHS), these commands are located hierarchically in the system as follows:

In addition to the system-level binaries, executable programs can also include host specific program commands.

When you install a program or application on your Mac through the internet, the application will be available to execute using GUI, usually from the /Application directory.

In order to use the command line command to run the application, however, the executable file for the application must be saved to the PATH variable. In other words, you must add the directory of the executable program file for the application to the PATH variable in order to use the name of the executable file as the command to run it from the shell.

When you install an application through a package manager, such as Homebrew, it is symlinked to /usr/local/bin, which is usually included in PATH.

For other direct program installations, it is your job to either save the original executable file to the PATH variable directly, or symlink the executable file to a separate bin folder, which would be included in PATH.

Let’s take a look at how we can go about adding these local application commands to the PATH variable so that we can use their commands in our shell.

Adding to PATH

In your zsh shell profile (.zshrc), you can add the following:

export PATH="/path/to/app/executable/file/directory:$PATH"

or

path+="/path/to/app/executable/file/directory"

export PATH=

export PATH="/path/to/app/executable/file/directory:$PATH

This syntax prepends /path/to/app/executable/file/directory to the existing PATH variable.

• export command allows all child processes to inherit the marked variable.
• $PATH refers to the PATH variable value
• assigning the path /path/to/app/executable/file/directory to the PATH variable with the trailing :$PATH essentially adds the path to the front of the existing PATH value with the separator :
• You can also append the path to the existing PATH (add to the end) by instead using
  export PATH="$PATH:/path/to/app/executable/file/directory"

path+=

path+="/path/to/app/executable/file/directory"

path is another variable that is tied to the PATH variable, but it is an array. PATH and path are tied together, so changing either one will change the other.

• however the variables’ value syntax are different:

>> echo $PATH
/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/path/to/app/......
>> echo $path
/usr/local/bin /usr/bin /bin /usr/sbin /sbin /path/to/app/......

• Note the PATH is separated by : while path is separated by whitespace.
• You can force the path variable to have only unique values by using typeset -U path command before path assignment. This will keep the path value clean by preventing duplicate directory names being added.

Here, the path/path/to/app/executable/file/directory will likely be a application bin directory starting from the /Applications directory.

• For example, for Visual Studio Code, the path is:

/Applications/Visual Studio Code.app/Contents/Resources/app/bin

• So, you would set:

export PATH="/Applications/Visual Studio Code.app/Contents/Resources/app/bin:$PATH"

This allows you to use the ‘code’ command (which is the name of the executable file) to run Visual Studio Code from the command line.

Symlinking the executable program file to a personal bin directory

Instead of adding each executable program file to the PATH separately, you can symlink the executable program file to a separate folder and add this folder to the PATH.

• This separate folder could be a bin folder on your home directory: ~/bin.
• You will have to create this in your home directory:

>> mkdir ~/bin

You can use ln command to symlink the executable file.

• ln is a utility program that creates a new directory entry (a linked file), which has the same modes as the original file. The link 'points' to the original copy. How the link 'points' to the original file is the difference between a hard link and a symbolic link.
• By default ln creates hard links, where any changes to the original file are effectively independent from the linked file.
• Using the -s flag creates a symbolic link (symlink), which is a soft copy, allowing for the use of the referenced file when an operation is performed on the linked file.

>> ln -s "/Applications/Visual Studio Code.app/Contents/Resources/app/bin/code" ~/bin

If you have the ~/bin directory added to the PATH variable, you just need to to symlink any executable program you want to add command for to the ~/bin directory.

This will make the organization of the PATH much cleaner and much easier to see what executable programs are included in the PATH.

References:

• https://en.wikipedia.org/wiki/Filesystem_Hierarchy_Standard
• https://askubuntu.com/questions/308045/differences-between-bin-sbin-usr-bin-usr-sbin-usr-local-bin-usr-local
• https://stackoverflow.com/questions/11530090/adding-a-new-entry-to-the-path-variable-in-zsh
• man ln