Initially, the owner of a file is the user who creates it. The chown command is used to change the ownership of files and directories. Changing the user owner requires administrative access. A regular user cannot use this command to change the user owner of a file, even to give the ownership of one of their own files to another user. However, the chown command also permits changing group ownership, which can be accomplished by either root or the owner of the file.
To change the user owner of a file, the following syntax can be used. The first argument, [OWNER], specifies which user is to be the new owner. The second argument, FILE, specifies which file's ownership is changing.
chown [OPTIONS] [OWNER] FILE
Follow Along
Use the following command to switch to the Documents directory:
sysadmin@localhost:~$ cd ~/Documents
Currently all the files in the Documents directory are owned by the sysadmin user. This can be verified by using the ls -l command. Recall that the third column indicates the user owner.
sysadmin@localhost:~/Documents$ ls -l total 144 drwx------ 5 sysadmin sysadmin 4096 Dec 20 2017 School drwx------ 2 sysadmin sysadmin 4096 Dec 20 2017 Work -rw-r--r-- 1 sysadmin sysadmin 39 Dec 20 2017 adjectives.txt -rw-r--r-- 1 sysadmin sysadmin 90 Dec 20 2017 alpha-first.txt -rw-r--r-- 1 sysadmin sysadmin 106 Dec 20 2017 alpha-second.txt -rw-r--r-- 1 sysadmin sysadmin 195 Dec 20 2017 alpha-third.txt -rw-r--r-- 1 sysadmin sysadmin 390 Dec 20 2017 alpha.txt -rw-r--r-- 1 sysadmin sysadmin 42 Dec 20 2017 animals.txt -rw-r--r-- 1 sysadmin sysadmin 14 Dec 20 2017 food.txt -rwxr--r-- 1 sysadmin sysadmin 647 Dec 20 2017 hello.sh -rw-r--r-- 1 sysadmin sysadmin 67 Dec 20 2017 hidden.txt -rw-r--r-- 1 sysadmin sysadmin 10 Dec 20 2017 letters.txt -rw-r--r-- 1 sysadmin sysadmin 83 Dec 20 2017 linux.txt -rw-r--r-- 1 sysadmin sysadmin 66540 Dec 20 2017 longfile.txt -rw-r--r-- 1 sysadmin sysadmin 235 Dec 20 2017 newhome.txt -rw-r--r-- 1 sysadmin sysadmin 10 Dec 20 2017 numbers.txt -rw-r--r-- 1 sysadmin sysadmin 77 Dec 20 2017 os.csv -rw-r--r-- 1 sysadmin sysadmin 59 Dec 20 2017 people.csv -rw-r--r-- 1 sysadmin sysadmin 110 Dec 20 2017 profile.txt -rw-r--r-- 1 sysadmin sysadmin 51 Dec 20 2017 red.txt
To switch the owner of the hello.sh script to the root user, use root as the first argument and hello.sh as the second argument. Don't forget to use the sudo command in order to gain the necessary administrative privileges. Use password netlab123 if prompted:
sysadmin@localhost:~/Documents$ sudo chown root hello.sh [sudo] password for sysadmin:
Confirm the user owner has changed by executing the ls -l command. Use the filename as an argument to limit the output:
sysadmin@localhost:~/Documents$ ls -l hello.sh -rwxr--r-- 1 root sysadmin 647 Dec 20 2017 hello.sh
The user owner field is now root indicating the change was successful.
-rwxr--r-- 1 root sysadmin 647 Dec 20 2017 hello.shConsider This
Try executing the hello.sh script again. It fails! Why?
sysadmin@localhost:~/Documents$ ./hello.sh -bash: ./hello.sh: Permission denied
Only the user owner has the execute permission, and now the root user is the user owner. This file now requires administrative access to execute. Use the sudo command to execute the script as the root user.
sysadmin@localhost:~/Documents$ sudo ./hello.sh [sudo] password for sysadmin: ______________ ( Hello World! ) -------------- \ \ <(^) ( )
