Bash Tutorial · Linux System Skills · Lesson 26 of 30

Bash Environment Variables and PATH

Use environment variables, export them to child processes, configure PATH, and set up your shell profile.

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Shell variables vs environment variables

A plain variable exists only in the current shell. export puts it in the environment, which child processes (scripts, programs) inherit.

export and one-off variables

greeting="hi"
bash -c 'echo "child sees: [${greeting:-nothing}]"'
export greeting
bash -c 'echo "child sees: [$greeting]"'
LOG_LEVEL=debug bash -c 'echo "one-off variable: $LOG_LEVEL"'

Output

child sees: [nothing]
child sees: [hi]
one-off variable: debug

Run this on your computer — see “Get Started” for setup.

PATH

PATH is a colon-separated list of directories searched for commands. Add your own tools directory to the front: export PATH="$HOME/bin:$PATH".

Adding a directory to PATH

mkdir -p "$HOME/bin"
printf '#!/usr/bin/env bash\necho "my tool runs"\n' > "$HOME/bin/mytool"
chmod +x "$HOME/bin/mytool"
command -v mytool || echo "mytool not found"
export PATH="$HOME/bin:$PATH"
mytool

Output

mytool not found
my tool runs

Run this on your computer — see “Get Started” for setup.

Making it permanent

Put exports in ~/.bashrc (interactive shells) or ~/.profile/~/.bash_profile (login shells), then source ~/.bashrc to reload.

Test yourself

What does export do?

Saves the variable to disk
Makes a variable available to child processes
Prints the variable
Makes it read-only

Show answer

Answer: Makes a variable available to child processes

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