Multifile Tapes

The name used to open the tape file determines certain characteristics of the connection, such as the recording density and whether the tape is automatically rewound when opened and closed.

To access a file on a tape with multiple files, first use the mt(1) utility to position the tape to the needed file. Then open the file as a no-rewind magnetic tape such as /dev/nrmt0. Referencing the tape with this name prevents it from being repositioned when it is closed. By reading the file until end-of-file and then reopening it, a program can access the next file on the tape. Any program subsequently referencing the same tape can access it where it was last left, preferably at the beginning of a file, or past the end-of-file record.

However, if your program terminates prematurely, it may leave the tape positioned anywhere. Use the SunOS mt(1) command to reposition the tape appropriately.