To kick things off what exactly are path variables? Well, in simple terms, they’re just environment variables that store paths (duh) for commonly used directories or programs. For example, let’s say you want to access your Documents folder from any directory on your system without having to type out the full path every time. You can set a path variable called $HOME/Documents and then use it in your commands like this:
# This script changes the current working directory to the Documents folder using a path variable.
# Set the path variable $HOME/Documents to the path of the Documents folder
DOC_PATH="$HOME/Documents"
# Change the current working directory to the Documents folder using the path variable
cd "$DOC_PATH"
# The "$" symbol is used to access the value of a variable, in this case, the path variable $DOC_PATH
# The double quotes around the variable ensure that any spaces in the path are properly handled
# Example:
# If the Documents folder is located at /home/user/Documents, then the path variable $DOC_PATH will be set to /home/user/Documents
# The command "cd $DOC_PATH" will then change the current working directory to /home/user/Documents
# Note: It is good practice to use double quotes around variables to avoid any issues with spaces or special characters in the path.
Pretty sweet, right? But what if you want to access a program that’s not in your PATH (the list of directories that are automatically searched for executable files)? Well, you can add it to your own custom PATH by setting another environment variable called $PATH. Here’s an example:
# This script adds a specified directory to the PATH environment variable, allowing access to programs not in the default PATH.
# It is useful for customizing the PATH to include directories with frequently used programs.
# First, we declare the export command to make the PATH variable available to child processes.
export PATH
# Next, we use the $PATH variable to append the specified directory to the existing PATH.
# This ensures that the original PATH is not overwritten and the new directory is added to the end.
# The colon (:) separates each directory in the PATH.
# The /path/to/your/program should be replaced with the actual path to the desired directory.
export PATH=$PATH:/path/to/your/program
# Now, the new directory is added to the PATH and any programs within it can be accessed from anywhere in the system.
# This is especially useful for programs that are not in the default PATH, such as custom scripts or applications.
# To add multiple directories, simply repeat the export command with different paths.
# It is important to note that the PATH is searched in order, so if a program exists in multiple directories, the one in the earlier directory will be executed.
# Therefore, it is recommended to add custom directories to the end of the PATH to avoid conflicts with existing programs.
Now when you run that program, Linux will automatically search for it in both your current working directory and the new directory you added. Pretty handy! But what if you want to remove a path from your PATH? Well, you can do that too by setting an empty value:
#!/bin/bash # shebang to specify the interpreter
# This script removes all paths from your PATH variable
# Use with caution!
export PATH="" # sets an empty value to the PATH variable, effectively removing all paths
# Note: the double quotes are necessary to ensure the variable is set to an empty string, otherwise it will be unset
# Explanation: The PATH variable is used by the shell to determine the locations where it should search for executable files. By setting it to an empty value, we are effectively removing all paths from the search list, which means the shell will not be able to find any executable files unless they are in the current working directory.
And there you have it the basics of path variables in Linux. Did you know that you can also set multiple values for a single variable by separating them with colons? For example:
#!/bin/bash
# This script sets the PATH variable to include both /bin and /usr/bin directories.
export PATH="/bin:/usr/bin" # sets the PATH variable to include both /bin and /usr/bin directories
Or how about setting path variables in your shell configuration file (usually .bashrc or .zshrc) so they’re automatically set every time you open a new terminal window? Here’s an example:
# This script adds a specified directory to the PATH variable in the .bashrc file, allowing for automatic setting of path variables every time a new terminal window is opened.
# First, we use the echo command to print a string to the terminal.
echo "export PATH=$PATH:/path/to/your/program"
# Next, we use the >> operator to append the output of the echo command to the .bashrc file.
# This ensures that the specified directory is added to the PATH variable in the .bashrc file.
# We also use the -i flag to ensure that the changes are made to the .bashrc file in the user's home directory.
echo "export PATH=$PATH:/path/to/your/program" >> ~/.bashrc
# Finally, we use the source command to reload the .bashrc file, ensuring that the changes take effect immediately.
source ~/.bashrc
And that, my friends, is all you need to know about path variables. So next time you’re struggling to remember where a certain program or folder is located, just remember it’s probably stored in one of those ***** environment variables!