chown
Description
chown stands for change owner which changes user or group ownership of a file, directory, or symbolic link. Every file or directory has group or user ownership in Linux. Since multiple users and groups can use same Linux system, they all have unique names and IDs. Name and ID of a user and a group can be same.
For displaying the owner of any file or folder, one can use
ls -l [file or folder name]
Example:
ls -l test.txt
Output:
-rw-rw-r-- 1 sasa sasa 0 Dec 3 21:42 test.txt
In above output section, first sasa denotes user and second sasa denotes its group.
You can also check the ownership of any folder. Suppose you are in folder which contains test_folder which you can check by using ls command then type command below to see ownership of your test_folder.
Examples:
ls -l
Output:
drwxrwxr-x 2 sasa sasa 4096 Dec 3 21:42 test_folder
1. Changing ownership of file to another user.
First, checking the ownership of file from the command below:
ls -l test.txt
Suppose output is:
-rw-rw-r-- 1 sasa sasa 0 Dec 3 21:42 test.txt
Now, suppose I want to change it to the user root from the user sasa; this can be done using the command below:
sudo chown root test.txt
Output:
-rw-rw-r-- 1 root sasa 0 Dec 3 21:42 test.txt
In above output section, ownership changed to user root from user sasa. Group sasa still has ownership.
Note:
You can also use owner user_id in place of owner to change ownership in above example like:
id -u user_name
Suppose, output is 1000.
Now, you can replace user_name with its user_id.
Example: In place of sudo chown user_name test.txt, you can use the command below:
sudo chown 1000 test.txt
Another Note:
For changing ownership of folder, you can do it similarly like:
sudo chown root test_folder
It gives ownership of test_folder to root user.
2. Changing the group of a file.
First, checking the ownership of file from the command below:
ls -l test.txt
Suppose output is:
-rw-rw-r-- 1 sasa sasa 0 Dec 3 21:42 test.txt
Now, suppose I want to change it to group root then it can be done by command below:
sudo chown :root test.txt
Output:
-rw-rw-r-- 1 root root 0 Dec 3 21:42 test.txt
Group of file test.txt changed from sasa to root.
Note:
You can also use owner group_id in place of group to change ownership in above example like:
id -g group_name
Example:
id -g root
Suppose, output is 0.
Now, you can replace group_name with its group_id.
Example:
In place of sudo chown group_name test.txt, you can use the command below:
sudo chown :0 test.txt
3. Changing both file ownership and group at once.
First checking the ownership of file from the command below:
ls -l test.txt
Suppose output is:
-rw-rw-r-- 1 root root 0 Dec 3 21:42 test.txt
Now, suppose I want to change it to user sasa and group sasa then it can be done by the command below:
sudo chown sasa:sasa test.txt
Output:
-rw-rw-r-- 1 sasa sasa 0 Dec 3 21:42 test.txt
Ownership changed to user sasa and group sasa.
4. Changing owner of multiple files
You can use different files with space in between them to change ownership of multiple files at once.
sudo chown owner_name file1 file2 file3
5. Copying owner and group of file to another file.
Syntax:
sudo chown --reference=source_file destination_file
Flags
--reference
Description:
--reference=RFILE: Reference a file to use its owner and group for another file (use RFILE's owner and group rather than specifying OWNER:GROUP values)
Usage:
sudo chown --reference=reference_file target_file
-v, --verbose
Description:
Verbose, its prints what action has happened when used.
Usage:
sudo chown -v new_owner:new_group target_file
-c, --changes
Description:
Like verbose but report only when a change is made.
Usage:
sudo chown -c new_owner:new_group target_file
-R, --recursive
Description:
Operates in files and directory recursively.
Usage:
sudo chown -R new_owner:new_group target_directory
--from=CURRENT_OWNER:CURRENT_GROUP
Description:
Change the owner and/or group of each file only if its current owner and/or group match those specified here. Either may be omitted, in which case a match is not required for the omitted attribute
Usage:
sudo chown --from=current_owner:current_group new_owner:new_group target_file
Use Case
Imagine you're managing a shared project on a Linux server, and a team member has recently left the project, leaving behind some crucial files in their home directory. To ensure continued access and collaboration, you need to transfer ownership of the files to a new team member. Using the chown command, you can swiftly change the ownership of the entire directory, including its subdirectories and files, to the new team member's user and group, ensuring seamless collaboration without any disruption in accessing or modifying the project files. The command would look something like this:
sudo chown -R new_user:new_group /home/old_user/project.
Exercises
Exercise 1: Change Ownership of a File
You have a file named important_document.txt in your home directory, and you want to change its ownership to a user named secure_user and a group named restricted_group. Use the chown command to accomplish this task.
Exercise 2: Recursively Change Ownership of a Directory
You have a directory named project_files in your home directory, and it contains multiple subdirectories and files. You want to change the ownership of the entire directory and its contents to a user named project_owner and a group named project_group. Use the chown command with the recursive flag to achieve this.
Exercise 3: Copy Ownership from a Reference Directory
You have two directories, source_directory and destination_directory. You want to set the ownership of the destination_directory to match that of the source_directory. Use the chown command with the --reference flag to copy the ownership from the source to the destination.