Mastering file permissions with the chmod command in Linux

Understanding File Permissions in Linux

File permissions in Linux are a crucial aspect of managing files and directories. They determine who can access files, modify them, or execute them. Linux uses a numeric system to set file permissions, with each digit representing a different level of access: owner, group, and others. In order to change file permissions, we use the chmod command.

The chmod Command

The chmod, or change mode, command can be used to change file permissions in Linux. The command takes several arguments, including the permissions set, the file or directory being modified, and the user or group being modified. Here is the syntax for the chmod command:

chmod [permissions] [file/directory] 

Setting File Permissions with chmod

File permissions are represented by three digits, each of which represents a different class of users: owner, group, and others.

– The first digit sets permissions for the owner of the file
– The second digit sets permissions for members of the group to which the file belongs
– The third digit sets permissions for all other users

Each digit can be set to a value from 0 to 7, with each value corresponding to a different set of permissions.

– 0 – no permissions
– 1 – execute only
– 2 – write only
– 3 – write and execute
– 4 – read only
– 5 – read and execute
– 6 – read and write
– 7 – read, write, and execute

Here are some examples of how the chmod command can be used:

chmod 700 examplefile.txt 

This command sets the file permissions for examplefile.txt so that the owner can read, write, and execute the file, and group members and other users have no access.

chmod 755 examplefolder 

This command sets the directory permissions for examplefolder so that the owner can read, write, and execute the folder, and all other users can read and execute the folder. Group members have the same permissions as other users.

Changing File Ownership with chmod

In addition to changing file permissions, the chmod command can also be used to change the ownership of files and directories. Here is the syntax for changing file ownership:

chmod [newowner:newgroup] [file/directory] 


Mastering file permissions with the chmod command in Linux is an essential skill for any system administrator or Linux user. By understanding the numeric system used to set file permissions and knowing how to use the chmod command, you can ensure that files and directories on your Linux system are secure and accessible only to those who need them.

Give it a try!

Now that you have an understanding of the chmod command in Linux, try experimenting with different file permissions and ownership settings to see how they affect access to files and directories on your system. The ability to manage permissions is a valuable skill that will serve you well in your journey as a Linux user.