What does the command 'chmod' do?

The command 'chmod' is used in Linux and Unix-like operating systems to change the permissions of a file or directory. Permissions determine who can read, write, or execute the file, which is crucial for system security and user access control.

When 'chmod' is used, it modifies the permission settings for three categories of users: the owner of the file, the group associated with the file, and all other users. It allows specific permissions to be granted or revoked according to the needs of the system and its users.

For instance, a user can use 'chmod' to allow others to read a file or to restrict write access to sensitive data. This makes it an essential tool for managing file security in a multi-user environment.

Other options, such as changing file ownership or directory names, are managed by different commands (like 'chown' for ownership and 'mv' for renaming). The execution status is also not directly altered by 'chmod'; rather, the command sets permissions that can influence whether a file can be executed by users.