What command is used to change file permissions in Linux?

The command used to change file permissions in Linux is "chmod." This is a fundamental command in Linux that allows users to modify the permissions associated with files and directories, which control who can read, write, or execute them.

Using "chmod," users can specify permissions numerically or symbolically. For example, with numerical representation, each permission type (read, write, execute) is associated with a specific number, and these numbers can be combined to set the desired permissions. Alternatively, symbolic notation allows users to add, remove, or set permissions using letters to specify user categories (owner, group, others) and permission types.

In contrast, the other command options provided serve different purposes. "chown" is used to change the ownership of a file or directory rather than permissions, and "chperm" and "changeauth" are not standard Linux commands for altering file permissions, which reinforces that "chmod" is the correct choice for this function.