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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?

Mike L.
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4 Answers4

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With GNU chmod (on Ubuntu) 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.

With BSD chmod (which is present on Mac OS X) you have to do it separately in two commands:

sudo chmod -R -x * && sudo chmod -R +X *

(If you want to include hidden files in the main directory as well, you likely need to change * to . (point), but it is untested.)

Arpad Horvath
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pabouk - Ukraine stay strong
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    On Ubuntu 13.04 a minor tweak is necessary: `chmod -R a-x+X *` – Eero Aaltonen Aug 22 '13 at 12:37
  • @EeroAaltonen: Thank you for the note. This could happen if your `umask` does not allow `x` permission for all. Do you use default `umask` or did you change it? Could you please send output of `umask` command? Besides your solution there is also this possibility: `chmod -R a-x,+X *` which will set the `x` permission according to your `umask`. I will update the answer but I would like to check the behaviour in BSD / Mac OS X first. – pabouk - Ukraine stay strong Aug 26 '13 at 17:22
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    @pabouk oopsie! It was actually the CentOs box where I had set my umask to 0007. – Eero Aaltonen Aug 28 '13 at 12:15
  • This is just sad... :( I like the `find` variant in the answer below for it's style of combining simple tools that do One Thing Well. – mikezter Aug 05 '14 at 18:00
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    Use `.` instead of `*` if you want this to be applied to all files – John Magnolia Apr 11 '15 at 04:49
  • @mikezter ...but `find` is a nightmare to learn how to use. – Kyle Strand Aug 04 '15 at 18:02
  • @pabouk: mind John's advise: by default `*` will not include hidden files in the starting directory. so `.` is preferable. – MestreLion Sep 16 '15 at 18:48
  • For the BSD chmod version, it seems to me that the second `sudo` is unneeded: `sudo chmod -R -x * && chmod -R +X *` works (the executable flags added on directories allow chmod to operate inside them next -- the reverse being the reason the first `sudo` is required indeed). – Socce Feb 21 '18 at 17:16
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If you cd into the correct path first:

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

or

chmod -x $(find . -type f)

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.

Kruug
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Matthijs P
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    If your `find` supports it, use `-exec ... \+` instead of `-exec ... \;` — it'll require fewer `fork`+`exec`s. If it doesn't, use `find ... -print0 | xargs -0 ...`. – ephemient Jun 08 '12 at 19:49
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    I've used this technique, but with "-perm +111" added to the find so it only chmod's ones that have the x-bit set: `find . -type f -perm +111 -exec chmod -x {} \;` – chrish May 28 '13 at 12:54
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    +1 @Matthijs The reason why this is better than pabouk's solution is that this command leaves directories alone, while pabouk's re-sets the executable bit in all directories. There might be some directories which have the executable bit not set, and pabouk's command sets it, while one might wish to leave them as they are. – MariusMatutiae Nov 09 '13 at 11:14
  • the 2nd approach will fail for paths that contain spaces. – MestreLion Sep 16 '15 at 18:50
  • @ephemient: if your `find` supports `-print0` I'm pretty sure it will also support `-exec` – MestreLion Sep 16 '15 at 18:52
4

Under Linux and Unix in a terminal window or On Mac OS X, use this in Terminal.app:

find . -type f -print0 | xargs -0 chmod -x
Drew Sullivan
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user227317
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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.

mic_e
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