pif: A simple diff wrapper for pip

pif.sh

# Diff pip freeze after pip install or uninstall
# Example usage: pif install foo
pif() {
    if [[ $@ == *'install'* ]]; then
        r1=$(mktemp) && pip freeze > r1
        pip "$@"
        r2=$(mktemp) && pip freeze > r2
        echo '  Pip freeze diff:'
        diff r1 r2
        rm -f r1 r2
    else
        pip "$@"
    fi
}

For maintaining requirements.txt I recommend pipreqs.