"chown" Command

Learn all about chown command

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The concept of owner and groups for files is fundamental to Linux. Every file is associated with an owner and a group. You can use chown command to change the owner or the group of a particular file or directory.

root:~# ls -l my_file
-rw-r----- 1 root root 12 Jul 21 14:28 my_file

root -- User of File
root -- Group of File

More information can be found:

root:~# man chown
root:~# chown --h

Example-1

1.1 Change the owner of a file

root:~# ls -l my_file
-rw-r----- 1 root root 12 Jul 21 14:28 my_file

root:~# chown www-data my_file

root:~# ls -l my_file
-rw-r----- 1 www-data root 12 Jul 21 14:28 my_file

1.2 Change the only group of a file

root:~# ls -l my_file
-rw-r----- 1 www-data root 12 Jul 21 14:28 my_file

root:~# chown :www-data my_file

root:~# ls -l my_file
-rw-r----- 1 www-data www-data 12 Jul 21 14:28 my_file

1.3 Change both owner and group

root:~# ls -l my_file
-rw-r----- 1 www-data www-data 12 Jul 21 14:28 my_file

root:~# chown root:root my_file

root:~# ls -l my_file
-rw-r----- 1 root root 12 Jul 21 14:28 my_file

Example-2

2.1 chown command on symbolic link file

root:~# ls -l link_my_file my_file
lrwxrwxrwx 1 root root  7 Jul 21 15:05 link_my_file -> my_file
-rw-r----- 1 root root 12 Jul 21 14:28 my_file

root:~# chown www-data:www-data link_my_file

root:~# ls -l link_my_file my_file
lrwxrwxrwx 1 root     root  7 Jul 21 15:05 link_my_file -> my_file
-rw-r----- 1 www-data www-data 12 Jul 21 14:28 my_file

When the chown command was issued on symbolic link to change the owner as well as the group then its the referent of the symbolic link i.e 'my_file' whose owner and group got changed. This is the default behavior of the chown command.

2.2 chown command to forcefully change the owner/group of symbolic file

root:~# ls -l link_my_file my_file
lrwxrwxrwx 1 root root  7 Jul 21 15:05 link_my_file -> my_file
-rw-r----- 1 root root 12 Jul 21 14:28 my_file

root:~# chown -h www-data:www-data link_my_file

root:~# ls -l link_my_file my_file
lrwxrwxrwx 1 www-data www-data  7 Jul 21 15:05 link_my_file -> my_file
-rw-r----- 1 www-data www-data 12 Jul 21 14:28 my_file

Using -h flag, you can forcefully change the owner and group of symbolic file

Example-3

3.1 Change owner only if a file is owned by a particular user
Using chown --from flag, you can change the owner of a file, only if that file is already owned by a particular owner.

root:~# ls -l tmpfile
-rw-r--r-- 1 root     root      3 Jul 21 15:17 tmpfile

root:~# chown --from=root www-data tmpfile
root:~# ls -l tmpfile
-rw-r--r-- 1 www-data root      3 Jul 21 15:17 tmpfile

root:~# chown --from=root man tmpfile
root:~# ls -l tmpfile
-rw-r--r-- 1 www-data root      3 Jul 21 15:17 tmpfile

- In the example above, it has been verified that the original owner/group of the file 'tmpfile' was root/root.
- Next we used '--from' flag to change the owner to 'www-data' if existing owner is root only.
- Now as existing owner is www-data so next chown commands failed to change owner as 'man'

3.2 Change group only if a file belongs to a certain group
Using chown --from flag, you can change the group of file as well.

root:~# ls -l my_file
-rw-r----- 1 www-data www-data 12 Jul 21 14:28 my_file

root:~# chown --from=:www-data :root my_file
root:~# ls -l my_file
-rw-r----- 1 www-data root 12 Jul 21 14:28 my_file

root:~# chown --from=:www-data :man my_file
root:~# ls -l my_file
-rw-r----- 1 www-data root 12 Jul 21 14:28 my_file