TestOut Linux Pro Practice Test 2025 – All-in-One Guide to Master Your Certification!

The command used to change file permissions in Linux is chmod. This command allows users to modify the read, write, and execute permissions for the owner of the file, the group associated with the file, and others. By using chmod, you can set permissions in symbolic mode (with letters like u for user, g for group, o for others) or numeric mode (using numbers to represent the permissions).

For example, you can grant execute permissions to the owner of the file using `chmod u+x filename`, or you can set multiple permissions at once using numeric representation, such as `chmod 755 filename`, which translates to full permissions for the owner and read-execute permissions for the group and others.

Other commands listed serve different purposes. Chown is used to change the ownership of a file or directory rather than its permissions. Chattr is used to change file attributes on a filesystem at a lower level. The term perm is not a standard command in Linux for modifying permissions, making chmod the appropriate choice for the question.