linux-path-variable
Adding a Path to the Linux PATH Variable
1. Overview
In this quick tutorial, we’ll focus on how to add a path to the Unix
PATH variable.
2. PATH Variable
The PATH variable is an environment variable that contains an ordered
list of paths that Unix will search for executables when running a
command. Using these paths means that we do not have to specify an
absolute path when running a command.
For example, if we want to print Hello, world!, the
command echo can be used rather than
/bin/echo so long as /bin is in PATH:
echo "Hello, world!"Unix traverses the colon-separated paths in order until finding an
executable. Thus, Unix uses the first path if two paths contain the
desired executable.
We can print the current value of the PATH variable by echoing the PATH
environment variable:
echo $PATHWe should see a list of colon-separated paths (exact paths may differ):
/usr/lib/lightdm/lightdm:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games3. Adding a New Path
We add a new path to the PATH variable using the
export command.
To prepend a new path, such as /some/new/path, we reassign the PATH
variable with our new path at the beginning of the existing PATH
variable (represented by $PATH):
export PATH=/some/new/path:$PATHTo append a new path, we reassign PATH with our new path at the end:
export PATH=$PATH:/some/new/path4. Persisting Changes
When we use the export command and open a new shell, the added path is
lost.
4.1. Locally
To persist our changes for the current user, we add our export
command to the end of ~/.profile. If the ~/.profile file
doesn’t exist, we should create it using the
touch command:
touch ~/.profileThen we can add our export command to ~/.profile.
Additionally, we need to open a new shell or source our ~/.profile
file to reflect the change. We’d either execute:
. ~/.profileor we could use the source command
if we are using Bash:
source ~/.profileWe could also append our export command to ~/.bash_profile if we are
using Bash, but our changes will be not be reflected in other shells,
such as Z shell (zsh). We shouldn’t
add our export command to ~/.bashrc because only
interactive Bash
shells read this configuration file. If we open a non-interactive shell
or a shell other than Bash, our PATH change will not be reflected.
4.2. Globally
We can add a new path for all users on a Unix system by creating a file
ending in .sh in /etc/profile.d/ and adding our export command to
this file.
For example, we can create a new script
file, /etc/profile.d/example.sh, and add the following line to append
/some/new/path to the global PATH:
export PATH=$PATH:/some/new/pathAll of the scripts in /etc/profile.d/ will be executed when a new
shell initializes. Therefore, we need to open a new shell for our global
changes to take effect.
We can also add our new path directly to the existing PATH in the
/etc/environment file:
PATH=<existing_PATH>:/some/new/pathThe /etc/environment file is not a script file—it only contains simple
variable assignments—and is less flexible than a script. Because of
this, making PATH changes in /etc/environment is discouraged. We
recommend adding a new script to /etc/profile.d instead.
5. Conclusion
In this tutorial, we saw how Unix uses the PATH variable to find
executables when running a command.
We can prepend or append to PATH, but we must persist these changes in
~/.profile. We can use ~/.bash_profile as well, but ~/.profile is
preferred.
We can also change the global PATH value by adding our export command
to a new .sh file in /etc/profile.d.
