Unix/Linux file ownership FAQ: How do I use the
chown command is most commonly used by Unix/Linux system administrators who need to fix a permissions problem with a file or directory, or many files and many directories.
For instance, suppose you want files to be owned by the user "nobody", but when you issue an
ls command, you see that they're owned by the user "fred", like this:
$ ls -l -rw------- 1 fred groupfred 1459 May 7 12:18 ltr1.txt -rw------- 1 fred groupfred 8156 May 7 11:27 ltr2.txt
To fix the file ownership (permissions) problem, you use the Linux
chown command. If you just want these files to be owned by the user nobody, you'd use this command:
chown nobody *txt
However, since these files are also in the group named "groupfred", you'll probably want to change the group as well. To change the owner and group in one command on Linux systems you can use this command:
chown nobody.nobody *txt
The way this works is that the first "nobody" string refers to the owner, and the second "nobody" string -- the one after the decimal -- refers to the group. Therefore, the general case looks like this:
chown owner.group file(s)
On older Unix systems you may have to use the
chgrp commands to achieve the same result, like this:
chown nobody *txt chgrp nobody *txt
(Where "chown" means "change owner", "chgrp" means "change group".)
Linux chown - Be careful
If you're not the root user on your Unix or Linux system -- or even if you are -- be very careful with the
chgrp commands. Once you grant ownership of files to another user on your Unix/Linux system, guess what? You don't own them any more. This can lead to all sorts of nasty problems, such as not being able to delete the files.
chgrp commands are commonly used by Unix system administrators (Unix 'root' users) and this isn't usually much of a problem, but I thought I better warn you about it anyway, as it can create a mess.