Boilerplate for writing "shell-like" Python scripts

python-shell-like-script.py

#!/usr/bin/env python

# both python 2 and 3 comatible
from __future__ import absolute_import, division, print_function, unicode_literals
try:
    input = raw_input
except NameError:
    pass

import sys
import os
import pwd
import argparse
from subprocess import call


# when in debug mode, just pretend to do stuff
# (output shell commands with "~" prefix)
DEBUG = False


arg_parser = argparse.ArgumentParser()
arg_parser.add_argument('--absPath', required=True)
arg_parser.add_argument('--wpUrl')
args = arg_parser.parse_args()

if not args.setupUser:
    args.setupUser = 'some user'


def do(str):
    """execute string command after replacing args in it"""
    str = str.format(**vars(args))
    print('\n~ ' + str)
    if DEBUG:
        return
    return call(str, shell=True)


def user_do(str):
    """
    execute command as user (useful when script needs to run as sudo, but
    some of the commands need to be un as a username given by argument --user)
    """
    do('sudo -u {} {}'.format(args.setupUser, str))


def require(cond):
    """stop execution if a condition is not satisfied"""
    if not cond:
        print("Abandoning...")
        sys.exit(1)


def confirm(str, defaultYes=True):
    """ask user for confirmation"""
    str += " " + ("[Y/n]" if defaultYes else "[y/N]")
    r = input(str) or 'y'
    require(r.strip().lower() == 'y')


print(
    """Will use:
    absPath: {absPath}
    user: {user}
    homeUrl: {homeUrl}
    urlPath: {urlPath}
    wpUrl: {wpUrl}
    db: {db}
    dbUser: {dbUser}
    dbPwd: {dbPwd}
    """.format(**vars(args))
)

confirm("Does this seem OK?")


# do somehting if a user exists and somehting else if it soes not
try:
    pwd.getpwnam(args.user)
    # user exists:
    # ...
except KeyError:
    # user does not exist (maybe create it?)
    # ...
    pass

# ugly way to do mysql commands
# (keep one per line to continue despite errors)
do("""mysql <<EOF
    CREATE USER USER IF NOT EXISTS '{dbUser}'@'localhost' IDENTIFIED BY '{dbPwd}';
EOF""")

# either cat-in or file operations, whatever one prefers...
do('cat <<EOF >> /etc/nginx/sites-available/_wps_lab.neuronq.ro\n' +
    nginx_conf + '\nEOF')
# with open('/home/neuronq/lab.neuronq.ro/etc/nginx.conf', 'a+') as f:
#     f.wite(nginx_conf)