Understanding Linux chmod and Permissions

In the world of Linux, chmod is a fundamental command that empowers users to manage file and directory access. It stands for "change mode," and it grants specific permissions to determine who can view, modify, or execute them.

Understanding File Permissions

Linux permissions are represented using a three-character sequence, where each character signifies a permission level for a particular user group:

• r (Read): Permission to view the contents of a file or directory listing.
• w (Write): Permission to modify the contents of a file or create new files within a directory.
• x (Execute): Permission to execute a file if it's a program or script.

User Groups

There are three primary user groups in Linux:

• User (Owner): The user who created the file or directory.
• Group: A designated group of users assigned specific permissions.
• Other: All users on the system who are not the owner or part of the assigned group.

chmod in Action

The chmod command follows this syntax:

chmod permission_code file_or_directory
        

For instance, to grant read and write permissions to the owner of a file named "myfile.txt" while giving only read access to the group and others, you would use:

chmod 644 myfile.txt
        

Decoding the Permission Code

In the above example, the permission code "644" translates to:

• 6 (4 + 2 + 0): Read and write (4) permission for the owner (user), read (2) permission for the group, and no permission (0) for others

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