mt:tldr:00ef3

The command "mt -f ${-dev-nstX} rewind" is used to rewind a tape drive specified by the device file represented by the variable ${-dev-nstX}.

Here's the breakdown of the command:

• "mt" is the command-line utility for controlling magnetic tape devices.
• "-f" is an option used to specify the device file to operate on.
• ${-dev-nstX} is a variable representing the device file associated with the specific tape drive. The value of X can be any specific number assigned to the tape drive.
• "rewind" is a subcommand for mt which tells the tape drive to rewind the tape to the beginning.

In summary, this command instructs the tape drive represented by the device file specified in ${-dev-nstX} to rewind the tape to its starting position.