Linux Change Mode

A specialized command-line utility in the Linux terminal used to edit permissions for files and directories.

Affected Entities

• Owner: the user account that owns the file or directory. Usually assigned to the user that created it, unless it has already been changed using chmod.
• Group: the group that owns the file or directory. Is usually set to the group that the owner belongs to, unless otherwise changed using chgrp.
• Others: refers to all other people that have access to the system

Entities can be abbreviated using u, g, o for the owner, the group, and other users

Applicable Permissions (File; Directory)

• Read: Allows the user to open and view a file; Allows for the directories contents to be listed.
• Write: Allows the user to modify a file; Allows the user to add and remove files from the directory
• Execute: Allows the user to execute the file; Allows the user to open/enter the directory.

Permissions can be abbreviated using r, w, x for read, write, and execution permissions

Syntax & Usage

• chmod <entity> = <permissions> filename
• chmod <entity> +/- <permissions> filename where the $\pm$ is used to indicate set or remove permissions

#IX