Command Line: Add Write Permissions to All Files and Folders

This is a tricky one.

Plenty of people are experts at command line wizardry in the Linux/UNIX/*nix world, and I'd say I'm pretty comfortable with it. Anything you want to do, there's usually some uber-command that does everything in one line, probably using the -exec option, it just requires some searching and a little trial and error (with caution).

But here's one I've had trouble with. We had a directory that had mixed permissions. Specifically, the user and group were set wrong, and the permissions were set to user-write only, or rw-r--r--. I wanted to change the user and group, and set the permissions to rw-rw-r--, so that the group can write as well.

So, the first problem wasn't that bad. I can use chown with the -R flag (recursive) to change to owner. So the first command looked like this:

chown -R user *

Then, the group can be similarly changed with the chgrp command:

chgrp -R group *

I might have needed to run one extra set of commands to catch any files that start with a dot (.), since they'll be ignored by the *.

Now, the tricky part. I can use chmod to change the file permissions. The thing is, files need rw-rw-r-- (664), but directories need rwxrwx-r-x (775). I can't just run chmod -R 664 * because that would mess up directories.

So, the first solution is a little clunkly...

You could use find with the -exec option. You'd have to run two commands, and here's what they look like:

find ./ -type f -exec chmod 664 {} \;
find ./ -type d -exec chmod 775 {} \;

So, to break this down, I'm using the find command on the current directory. -type f means I'm looking for files of type "file". So, it will only return files, not directories. Then I use the -exec option to run the chmod command. The {} are where the replacement goes in, and the \; is just standard syntax. The second command uses -type d, which searches only directories and excludes files.

It works, but there's actually a shorter, one-line command to do both operations. Turns out, chmod can take the octal values (000-777), or it can use "symbolic mode". Using this mod, 'a', 'u', 'g', 'o' stand for 'all', 'user', 'group', 'other', respectively, and permissions are added or taken away using plus (+) and minus (-).

This makes my command really simple. All I want to do is add write permissions for groups on all files and directories. Assuming files currently have a permission of rw-r--r-- (644), and directories have a permission of rwx-r-x-r-x (755), all I have to do is run this command:

chmod -R g+w *

g+w translates to "grant the group write permissions".

And that's it!

P.S. If this keeps happening (as it does to me), it may be a good idea to set the umask variable in your account profile. umask works a little weird, there's an article explaining it here, but the value I would need to add for 664 and 775 permissions by default is this:

umask 002