Introduction to chown command in Linux
chown, which stands for change owner, is a command in Linux to change user or group ownership of a file, directory, or symbolic link. Every file or directory has a user or group ownership in the Linux systems. The Linux system can have multiple users and groups. They all have unique names and IDs. However, the name and ID of a user and a group can be the same.
Different examples to use chown command
chown command requires root permissions for its execution. You have to log in as a root user or use sudo in front of chown command.
To view the owner and group , you can use ls-l command. Here, test is the name of a file. The first home is owner and the second home is group.
$ ls -l test -rw-rw-r-- 1 home home 42 Aug 29 21:58 test
In this tutorial, you will learn the different ways to change owner and group of a file, directory, or symbolic link using chown command.
1. Change the owner of a file using chown command
This is a simple chown command that changes the owner/user of a file. It requires a new owner name and file name. The new owner must be a valid user.
$ sudo chown new_owner file_name
Sample Output:
2. Change the group of a file using chown command
chown command allows you to change the group of a file. You must use a colon in front of a new group name. Otherwise, it will be considered as a new owner.
$ sudo chown :new_group file_name
Sample Output:
3. chown command to change the owner using user ID
chown command also changes the owner of a file with numeric user ID. But there should not be any other user having the same name as userID. You can use id -u user_name to print the user ID of a user.
$ sudo chown user_ID file_name
Sample Output:
4. chown command to change the group using group ID
You can change the group of a file using group ID instead of group name. id -g group_name prints the group ID.
$ sudo chown :group_id file_name
Sample Output:
5. chown command to change owner of multiple files
This is a useful command that allows you to change owner of multiple files simultaneously. You have to separate file names with a space. It will assign same owner to all mentioned files.
$ sudo chown new_owner file_name1 file_name2 file_name3
Sample Output:
6. Change owner and group name at the same time with chown command
chown command allows you to change owner and group name at the same time. You have to provide both new owner and group name in order to assign them in a file.
$ sudo chown new_owner:new_group file_name
Sample Output:
7. chown command to copy owner and group name from one file to another
This command copies the owner and group name from one file and assigns the same ownership to another file in the same directory.
$ sudo chown --reference=souce_file destination_file
Sample Output:
8. Print the changes made by chown command
This command prints the changes made by chown command in detail. By default, chown command prints nothing.
$ sudo chown -v
Sample Output:
It also prints the information when the owner or group name is not changed.
9. chown command to print the detail only if changes are made
Unlike the previous command, it prints the information only if the changes are made in the owner or group name. It does not print anything if the changes are not made in the owner or group name.
$ sudo chown -c
Sample Output:
10. chown command to change owner or group of a directory
Using the directory name instead of the file name, you can change the owner or group of a directory using chown command. You can also use directory path.
For changing the owner of a directory:
$ sudo chown new_owner directory_name
Sample Output:
For changing the group of a directory:
$ sudo chown :new_group directory_name
Sample Output:
11. Change owner of a file using chown command if only the current owner matches
This command assigns the new owner to a file if only its current owner matches. --from option verifies the current owner.
$ sudo chown --from=current_owner new_owner file_name
Sample Output:
If the current owner does not match, then the file owner will remain unchanged.
Sample Output:
12. chown command to change group of a file only if the current group matches
Similar to the previous command, it only allows you to change the group of a file if the current group matches. --from option also verifies the current group of a file.
$ sudo chown --from=:current_group :new_group file_name
Sample Output:
You can also use --from option to verify the current owner and group and assign a new owner and group at the same time.
$ sudo chown --from current_owner:current_group new_owner:new_group file_name
Sample Output:
13. Change the owner or group of files using chown command
-R option allows you to change the owner or group of files and sub-directories recursively present in the same directory. It is very useful when there are large number of files that need same ownership.
sudo chown -R new_owner:new_group directory_name
Sample Output:
14. chown command to change ownership of a symbolic link file
A symbolic link file is a type of file that points to another file. You can create a symbolic link by using:
$ ln -s source_file sym_file
To change the ownership of a symbolic link file using chown command, you have to use -h option to apply the changes. Otherwise, the changes will apply to the main file.
$ sudo -h new_owner:new_group sym_file
Sample Output:
Without using -h option:
As you can see in the above output, the ownership of 'test' is changed instead of 'symtest'.
15. Hide error message in the output with chown command
This command hides the error message in the output when the file or directory is not found.
$ sudo chown -f new_owner file_name
Sample Output:
It does not hide the error message printed due to invalid user, group, or syntax.
Conclusion
These are the most important chown commands in Linux. Now, you can easily change the user and group ownership of a file, directory, or symbolic link in the Linux systems.
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