Which command can be used to change the permissions of a file?

The command used to change the permissions of a file in Linux is chmod. This command is essential for managing file access controls, allowing users to define who can read, write, or execute a file. The chmod command works by modifying the file's permission set, which can be specified either numerically (using octal values) or symbolically (using letters to represent user categories and permissions).

For example, chmod 755 myfile sets the file's permissions to read, write, and execute for the owner and read and execute for the group and others. Understanding how to use chmod effectively is crucial for maintaining security and managing access within a Linux system.

The other options do not serve the purpose of changing file permissions. chown is used to change the ownership of a file, while filemode and permchange are not valid commands in Linux for adjusting file permissions. Thus, chmod stands out as the correct and relevant command for this task.