PIP install package and save to requirements.txt

pipis.sh

#!/bin/bash

pip_install_save() {
    package_name=$1
    requirements_file=$2
    if [[ -z $requirements_file ]]
    then
        requirements_file='./requirements.txt'
    fi
    pip install && pip freeze | grep -i $package_name >> $requirements_file
}

pip_install_save $1 $2