User's Guide

FSF

Forward skip files on a tape device

Function:

Forward spaces a specified number of files on the specified DITTO device. The user has the option to forward space files on the input device or output device.

Parameters:

DEVTYPE
Device type. Specifies which input/output device is to be processed. Valid values are:


  = INPUT:  Input device
  = OUTPUT: Output device

NFILES(0)
Number of files. Specifies the number of files to be forward spaced on the input or output DITTO device.

Examples:

  1. DITTO> fsf devtype=input nfiles=2

    The user has specified to forward space two files from the current position of the input device.

               Before:
               file ptr.
                   |
                   v
               ------------------------------------------------
               |            |E|            |E|            |E|E|
               |   file 1   |O|   file 2   |O|  file 3    |O|O|
               |            |F|            |F|            |F|F|
               ------------------------------------------------
    
               After:
                                         file ptr.
                                             |
                                             v
               ------------------------------------------------
               |            |E|            |E|            |E|E|
               |   file 1   |O|   file 2   |O|  file 3    |O|O|
               |            |F|            |F|            |F|F|
               ------------------------------------------------
    

  2. DITTO> fsf devtype=output nfiles=3

    The user has specified to forward space three files from the current position of the output device.

               Before:
               file ptr.
                   |
                   v
               ------------------------------------------------
               |            |E|            |E|            |E|E|
               |   file 1   |O|   file 2   |O|  file 3    |O|O|
               |            |F|            |F|            |F|F|
               ------------------------------------------------
    
               After:
                                                        file ptr.
                                                            |
                                                            v
               ------------------------------------------------
               |            |E|            |E|            |E|E|
               |   file 1   |O|   file 2   |O|  file 3    |O|O|
               |            |F|            |F|            |F|F|
               ------------------------------------------------
    

Description/Algorithm:

The parameters are input into the program. From the parameter DEVTYPE, it is determined which DITTO device is to be processed. The specified number of files are forward spaced from the current position of the DITTO device.

Nonfatal Error Messages:

    None.

Fatal Error Messages:

    None.

User Note:

  1. If end of volume (EOV) is detected on tape, the tape is left positioned between the two tape marks.

                                  file ptr
                                      |
                                      v
         --------------------------------
         |                          |E|E|
         |                          |O|O|
         |                          |F|F|
         --------------------------------