Conditionals in Bash

Scripts need to make decisions. We use if, elif, else, and fi.

Syntax

Bash is very strict about spaces inside the brackets [ ].

#!/bin/bash
if [ -f "config.json" ]; then
    echo "Config file exists!"
else
    echo "Creating default config..."
    touch config.json
fi

Common File Tests

• -f file: True if file exists and is a regular file.
• -d dir: True if directory exists.
• -z string: True if string length is zero.
• $A -eq $B: True if A equals B (integers).