How to remove executable bit recursively from files (not directories)

Question

When I plug-in an USB stick (FAT) into my Mac or Ubuntu machine, all files have the executable bits set. After having copied the directory structure to my hard disk how do I remove the executable bits recursively just from the files and keep those on the directories?

Answer 1

A single command variant (starting in the current directory):

chmod -R -x+X *

Explanation:

• -R - operate recursively
• -x - remove executable flags for all users
• +X - set executable flags for all users if it is a directory

In this case the capital X applies only to directories because all executable flags were cleared by -x. Otherwise +X sets executable flag(s) also if the flag was originally set for any of user, group or others.

Note: I tested the command with GNU chmod (on Ubuntu). I am not sure about the BSD chmod which is present on Mac OS X.

Answer 2

If you cd into the correct path first:

find . -type f -exec chmod -x {} \;

The find finds all files of type 'f' (which means regular file) in the path . and then calls chmod -x on each file. The {} gets substituted for the file name and the \; terminates the chmod command.

Answer 3

The chmod -x+X way did not work for me on ubuntu either, thus I wrote this minimal python script:

#!/usr/bin/python3
import os
for par, dirs, files in os.walk('.'):
    for d in dirs:
        os.chmod(par + '/' + d, 0o755)
    for f in files:
        os.chmod(par + '/' + f, 0o644)

If there might be any fancy extra stuff such as sockets in your filesystem, you may want to surround the last chmod with a try/catch.