How do you do a simple "chmod +x" from within python?

For tools that generate executable files (e.g. scripts), the following code might be helpful:

def make_executable(path):
    mode = os.stat(path).st_mode
    mode |= (mode & 0o444) >> 2    # copy R bits to X
    os.chmod(path, mode)

This makes it (more or less) respect the umask that was in effect when the file was created: Executable is only set for those that can read.

Usage:

path = 'foo.sh'
with open(path, 'w') as f:           # umask in effect when file is created
    f.write('#!/bin/sh\n')
    f.write('echo "hello world"\n')

make_executable(path)

Use os.stat() to get the current permissions, use | to OR the bits together, and use os.chmod() to set the updated permissions.

Example:

import os
import stat

st = os.stat('somefile')
os.chmod('somefile', st.st_mode | stat.S_IEXEC)

If you're using Python 3.4+, you can use the standard library's convenient pathlib.

Its Path class has built-in chmod and stat methods.

from pathlib import Path
import stat


f = Path("/path/to/file.txt")
f.chmod(f.stat().st_mode | stat.S_IEXEC)