Which command is utilized to change a file's permissions?

The command used to change a file's permissions in Unix and Unix-like operating systems is 'chmod', which stands for "change mode." This command allows users to define who can read, write, or execute a file. The permissions can be specified in numeric format (using octal numbers) or symbolic format (using letters to represent user categories and permissions).

Using 'chmod' provides flexibility in setting permissions for the owner of the file, the group associated with the file, and all other users. By combining different symbols or numbers, you can easily set the desired access levels for various users or roles regarding a specific file.

The other options serve different purposes:

• The 'chown' command is used to change the ownership of files and directories rather than permissions.

• 'mod' is not a recognized command in this context and doesn't perform any related file permission operations.

• 'chperm' is not a standard command found in Unix-based systems for modifying file permissions.

Thus, 'chmod' is indeed the correct command for altering file permissions.