Which command is used to change file permissions in Linux?

The command utilized to change file permissions in Linux is "chmod." This command allows users to specify which users or groups can read, write, or execute a file or directory. The name "chmod" stands for "change mode," which reflects its function of modifying the permission settings associated with files and directories.

When using "chmod," permissions can be assigned using symbolic notation (like 'r' for read, 'w' for write, and 'x' for execute) or numeric mode (where permissions are represented by octal numbers). For instance, the command chmod 755 file.txt grants the owner read, write, and execute permissions, while giving read and execute permissions to the group and others.

The other commands listed serve different purposes: "chown" is used to change the ownership of files and directories, "chgrp" modifies the group associated with a file, and "mod" is not a valid command in this context. Understanding "chmod" is crucial for managing security and access control in a Linux environment, as file permissions play a vital role in system security.