Linux chmod Command

In this tutorial, we will learn about the chmod Linux command with Examples. chmod is a short form of ‘change mode’ .

The <em>chmod</em> command in Linux is used to change the modes and permissions of files and directories. Permissions determine who can read, write, or execute a file.

Linux follows a permission model that includes three types of users: the owner, the group, and others. The <em>chmod</em> command allows users to modify these permissions using symbolic or numeric modes.

chmod Flags

Flag	Description
-R	Recursively change permissions for all files and directories inside a specified directory.
--reference=FILE	Change permissions to match those of a specified file.
--verbose	Display detailed information about the permission changes.
--silent or --quiet	Suppress error messages.

 

Examples

Give Executable Permission to a Script File

To make a script file executable, use the following command:

$ chmod +x script.sh

 

Notice how the script.sh changed to green color after giving the executable permission. Now, you can run the script using:

$ ./script.sh

Set Read, Write, and Execute Permissions for the Owner

To allow the owner to read, write, and execute a file while giving others only read permission:

$ chmod 744 file.txt

You can also use symbolic notation:

$ chmod u=rwx,g=rx,o= file.txt

The above chmod command grants the owner read, write, execute, the group read and execute, and others no permissions on the file.

 

Remove Write Permission from a File

To remove write permission for all users:

$ chmod a-w file.txt

Recursively Change Permissions of a Directory

To make all files inside a directory readable and executable for everyone:

$ chmod -R 755 /path/to/directory

 

The number 755 in chmod represents the permission settings for a file or directory. It consists of three digits, each corresponding to a different user category: owner, group, and others.

 

Digit	Binary	Permission	Description
7	111	rwx	Owner has read (r), write (w), and execute (x) permissions.
5	101	r-x	Group has read (r) and execute (x) permissions, but no write permission.
5	101	r-x	Others have read (r) and execute (x) permissions, but no write permission.

Set Permissions to Match Another File

To copy the permissions of one file to another:

$ chmod --reference=example.txt myfile.txt

 

Linux Basic Commands

• https://www.testingdocs.com/linux-basic-commands-tutorial/