A git pre-commit hook to check the year of copyright notices

Like every year, touching a source file means you also need to update the year of the copyright notice you should have at the top of the file. I always end up forgetting about them, this is where a git pre-commit hook would be ultra-useful, so I wrote one:

#
# Check if copyright statements include the current year
#
files=git diff --cached --name-only
year=date +"%Y"

for f in $files; do
    head -10 $f | grep -i copyright 2>&1 1>/dev/null || continue

    if ! grep -i -e "copyright.*$year" $f 2>&1 1>/dev/null; then
        missing_copyright_files="$missing_copyright_files $f"
    fi
done

if [ -n "$missing_copyright_files" ]; then
    echo "$year is missing in the copyright notice of the following files:"
    for f in $missing_copyright_files; do
        echo "    $f"
    done 
    exit 1
fi

Hope this helps!