Check object existence using IFS API

This solution uses one of the IFS Unix-type APIs that gives direct feedback on the existence of any object.

Vernon Hamberg

Published: 30 Apr 2003

In order to determine whether an object in a library exists, we can use the CHKOBJ command. There is no command-line equivalent for IFS objects. Some have suggested using spooled files. This solution uses one of the IFS Unix-type APIs that gives direct feedback on the existence of any object. This also works with library objects, using path naming.

Attached are command source with its processing program, as well as a test case that executes the command.

The command will run only in programs or REXX procedures, since it returns a value. The test case command can run anywhere.

Some techniques are illustrated:

1. The access() API requires a null-terminated path name, so the CPP shows how this can be done easily, using a variable length parameter in the command.

2. Many APIs that are most easily used in C/C++ can also be used in CLLE programs, as this example demonstrates. The service program that contains the API is automatically bound because of the standard binding directory that is used for CLLE compilation.

3. The API returns an integer. It is necessary to use the %BIN() function in the RTNVAL parameter of CALLPRC.

4. Using a command for the test case avoids the problem of garbage in the CL path name parameter if the test case program is called from a command line.

 To create objects (debug is optional):

CRTBNDCL PGM(SOMELIB/OBJEXISTS) SRCFILE(SOMELIB/QCLSRC)
          REPLACE(*YES) DBGVIEW(*ALL)
CRTBNDCL PGM(SOMELIB/TSTOBJEXST) SRCFILE(SOMELIB/QCLSRC)
          REPLACE(*YES) DBGVIEW(*ALL)
CRTCMD CMD(VERN/TSTOBJEXST) PGM(TSTOBJEXST) SRCFILE(SOMELIB/QCMDSRC)
        PRDLIB(SOMELIB) REPLACE(*YES)
CRTCMD CMD(SOMELIB/OBJEXISTS) PGM(OBJEXISTS) SRCFILE(SOMELIB/QCMDSRC)
        ALLOW(*BPGM *IPGM *BREXX *IREXX *BMOD *IMOD)
        PRDLIB(SOMELIB) REPLACE(*YES)

Check out the commands below: