Auto-evaluate variables in a string, especially useful when writing a shell-scripts in Python

shell_commands.py

from fabric.api import local

def sh(command, *args, **kwargs):
    frame = inspect.currentframe()
    ctx = frame.f_back.f_globals.copy()
    ctx.update(frame.f_back.f_locals)
    command = command.format(**ctx)
    del frame
    return local(command, *args, **kwargs)

def resign_ipa(uapp_name, unsigned_app, target_dir):
    sh('mkdir -p {target_dir}/Payload')
    sh('cp -r "{unsigned_app}" {target_dir}/Payload')
    sh('rm -rf {target_dir}/{app_name}.app/_CodeSignature')
    ...