What does the 'chmod' command do?

The 'chmod' command is used to change the file permissions in a Linux system. Understanding file permissions is crucial for managing access rights to files and directories, which is an essential aspect of system security.

When you use 'chmod,' you can specify the permissions that users, groups, and others have concerning a file or directory. Permissions can include read (r), write (w), and execute (x) rights, which can be assigned or revoked. For example, using 'chmod 755 filename' would give the owner of the file full permissions (read, write, and execute), while the group and others would only have read and execute permissions but no write permission.

This command is a fundamental part of security management, allowing administrators to control who can access and modify system files. The other choices relate to different functionalities not associated with the 'chmod' command: changing file ownership is handled by 'chown'; displaying system information can be done using commands like 'uname' or 'top'; and creating a new directory is accomplished with the 'mkdir' command. These distinctions help clarify the specific purpose of 'chmod' within the broader context of file management in Linux.