Variables

Shell Variables

The shell lets you store values in variables. You can then use those values in commands.

Assigning a Variable

NAME="Linux"

• No spaces around =. Spaces would break the assignment.
• No $ when assigning — only when reading.

Reading a Variable

Prefix the variable name with $ to expand it:

NAME="Linux"
echo "Hello, $NAME!"

Output:

Hello, Linux!

Quoting Rules

NAME="World"
echo "Hello, $NAME"    # Hello, World
echo 'Hello, $NAME'    # Hello, $NAME

Braces for Disambiguation

When the variable name could be confused with surrounding text, use ${VAR}:

VERSION="2"
echo "v${VERSION}.0"    # v2.0

Without braces, the shell would try to expand $VERSION followed by the literal .0 — which happens to work here, but ${VERSION} makes it explicit.

Environment Variables

Some variables are set by the shell and available to all programs:

• $HOME — your home directory (/home/user)
• $USER — your username (user)
• $PATH — directories searched for executable commands

Your Task

Assign the value Linux to a variable called NAME, then use echo to print Hello, Linux!.