FINDVOL: check for a file's existence

Description

A subroutine that tests for the presence or absence of a file.

Categories

Program Development

Related files

FINDVOL: Object file for utility.

TESTVOL: Demonstration program for FINDVOL.

User Instructions

Program subroutine; cannot be run interactively. (For test purposes see TESTVOL, a demonstration program.)

Programmer Instructions

Accepts five arguments and returns a numeric code indicating the results of the process.

Requires the following information:

  Type      PIC X(01)       Must be "I" (say "eye") to test
                            for a file's presence or "O" (say
                            "oh") to test for it's absence.

  File      PIC X(08)       Name and location of the file to
  Library   PIC X(08)       be tested.
  Volume    PIC X(08)

  Return    4-byte integer  Return code from FINDVOL.

The return code can be analyzed as follows:

  Type = "I":  0    One file found
               4    File not found
               8    File on more than one volume
              18    Invalid parameters

  Type = "O":  0    Library found
               4    File not found
              12    File exists
              18    Invalid parameters

ISWU documentation is available.

Example of use

Use in a program to determine whether a file exists (the "I" option) or whether an output file name already exists (the "O" option).

Comments

Many uses for FINDVOL have been superseded by the IF EXISTS clause in Procedure language.