How can I programmatically (in a shell script) determine whether or not there are changes?

Question

I am trying to create a Bash script that knows if there are changes in current working directory. I know that

$ git status

returns a messag

Answer 1

You can check if the variable is set by using the -n expression.

#!/bin/bash
CHANGESTOCOMMIT=$(git status | grep 'Changes to be com')
UNSTAGEDCHANGES=$(git status | grep 'Changes not staged')

# If there are staged changes:
if [ -n "$CHANGESTOCOMMIT" ]; then
    echo "Changes need to be committed"
fi
if [ -n "$UNSTAGEDCHANGES" ]; then
    echo "Changes made but not staged."
fi

Git tracks changed files that are both staged for committing, and also unstaged files, so your script might want to check both options (or not). The -n operator checks to see if the variable has been set - if it is empty it will return false.

An alternative is -z which returns True if it is empty (the logical opposite of -n. For a full list of conditional expressions please refer to the Bash Reference Manual.