Which command is used to change file permissions?

The command used to change file permissions in a Linux environment is chmod. This command allows users to modify the read, write, and execute permissions of files and directories. The syntax for chmod enables specifying permissions for the owner of the file, group members, and others, using either symbolic notation (like u+x to add execute permission for the user) or numeric representation (like 755, which specifies different permissions in a three-digit octal format).

Other commands provided as choices serve different functions:

• chown is used to change the ownership of a file or directory, not the permissions.

• ls lists files and directories along with their attributes but does not modify any permissions.

• cp is used for copying files and directories without affecting their permissions.

Thus, chmod is the correct command because it is specifically designed for changing file permissions.