Course/Environment & Variables/Setting Variables

Setting Variables

Learn to create your own variables with export and understand the difference between shell and environment variables.

You're not limited to the built-in variables — you can create your own. There are two kinds of variables in the shell: shell variables (local to your current session) and environment variables (available to your session and any programs you launch from it). The difference matters when you run scripts or other programs that need access to your values.

To create a shell variable, just assign it: GREETING=hello. No spaces around the = sign — this is a common mistake. To promote it to a full environment variable (so child processes can see it), use export: export GREETING=hello. Once set, you reference it with $GREETING.

export MY_NAME="terminal learner"
echo $MY_NAME

Variables set this way only last for the current session. When you close the terminal, they're gone. To make variables permanent, you'd add the export line to a configuration file like ~/.bashrc or ~/.zshrc — but that's a topic for a later module.

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Remember: no spaces around the equals sign. MY_VAR="hello" works. MY_VAR = "hello" does not — the shell thinks you're trying to run a command called MY_VAR with arguments = and hello.

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Be careful not to overwrite important system variables like PATH or HOME. If you accidentally clear PATH, your shell won't be able to find any commands until you fix it or open a new terminal.

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In PowerShell, you set variables with $MyVar = "value" (spaces are fine). To set a persistent environment variable, use [Environment]::SetEnvironmentVariable("MY_VAR", "value", "User"). In Command Prompt, use set MY_VAR=value for the session or setx MY_VAR value for persistence.

Try it yourself. Use export to create a variable, then use echo with a $ prefix to read it back.

export FAVORITE_COLOR="blue"
echo $FAVORITE_COLOR

Practice