Changing File Ownership

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 require 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 of which file the 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 the third column indicates the user owner.

sysadmin@localhost:~/Documents$ ls -l                                           
total 148                                                                       
drwxrwxr-x 2 sysadmin sysadmin  4096 Aug  1 03:40 School                        
drwxrwxr-x 2 sysadmin sysadmin  4096 Aug  1 03:40 Work                          
-rw-r--r-- 1 sysadmin sysadmin    39 Mar 14 17:48 adjectives.txt                
-rw-r--r-- 1 sysadmin sysadmin    90 Mar 14 17:48 alpha-first.txt               
-rw-r--r-- 1 sysadmin sysadmin    89 Mar 14 17:48 alpha-first.txt.original      
-rw-r--r-- 1 sysadmin sysadmin   106 Mar 14 17:48 alpha-second.txt              
-rw-r--r-- 1 sysadmin sysadmin   195 Mar 14 17:48 alpha-third.txt               
-rw-r--r-- 1 sysadmin sysadmin   390 Mar 14 17:48 alpha.txt                     
-rw-r--r-- 1 sysadmin sysadmin    42 Mar 14 17:48 animals.txt                   
-rw-r--r-- 1 sysadmin sysadmin    14 Mar 14 17:48 food.txt                      
-rwxrw-r-- 1 sysadmin sysadmin   112 Aug  1 03:48 hello.sh                      
-rw-r--r-- 1 sysadmin sysadmin    67 Mar 14 17:48 hidden.txt                    
-rw-r--r-- 1 sysadmin sysadmin    10 Mar 14 17:48 letters.txt                   
-rw-r--r-- 1 sysadmin sysadmin    83 Mar 14 17:48 linux.txt                     
-rw-r--r-- 1 sysadmin sysadmin 66540 Mar 14 17:48 longfile.txt                  
-rw-r--r-- 1 sysadmin sysadmin   235 Mar 14 17:48 newhome.txt                   
-rw-r--r-- 1 sysadmin sysadmin    10 Mar 14 17:48 numbers.txt                   
-rw-r--r-- 1 sysadmin sysadmin    77 Mar 14 17:48 os.csv                        
-rw-r--r-- 1 sysadmin sysadmin    59 Mar 14 17:48 people.csv                    
-rw-r--r-- 1 sysadmin sysadmin   110 Mar 14 17:48 profile.txt                   
-rw-r--r-- 1 sysadmin sysadmin    51 Mar 14 17:48 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 netlab123when 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                                  
-rwxrw-r-- 1 root sysadmin 112 Aug  1 03:48 hello.sh  

The user owner field is now root indicating the change was successful.

Consider This

If we try to execute the hello.sh script again. It will fail! 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:                                                   
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( Hello World! )                                                                
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