Here’s the 6th set of 20 AS400/IBM i interview Q&A. These are very practical and tricky, so I’ve explained with clarity.

1. When do we use CLOF command?

• CLOF (Close File) closes a database or device file explicitly in CL.

• Used when you want to release file resources before program ends.

2. Is there any similarity between the commands ALCOBJ and CHKOBJ?

• ALCOBJ → Allocates an object exclusively for a job.

• CHKOBJ → Checks whether an object exists.

• Similarity: both work with object attributes, but ALCOBJ locks while CHKOBJ only verifies.

3. What does DSPPGMREF do?

• Displays object references (files, modules, service programs) used by a program.

• Helps in impact analysis when changing files.

4. Why can’t retrieve commands be used on the command line?

• RTVxxx (Retrieve) commands require a CL variable to store results.

• Since command line doesn’t allow variable declaration, they can’t be used there.

5. Is recursion allowed on CL programs?

• No, recursion is not supported in CL programs.

6. Do all the objects referred to in a CL program need to exist at compilation time?

• No. They are validated only when the command is executed at runtime.

• However, command existence must be verified at compile time.

7. What is the difference between continuing a source statement with a plus sign (+) and a minus sign (-)?

• + → Continues statement by concatenating without a space.

• - → Continues statement by concatenating with one space.

8. What are the different ways to pass data between programs? Which is most efficient?

• Ways:

  1. Parameters (PARM)

  2. *Data areas (DTAARA)

  3. *Data queues (DTAQ)

  4. Files

• Parameters are most efficient (direct memory passing).

9. To view the program source we generally use option 2 or 5 on PDM. Any other way?

• Yes: DSPPFM FILE(QRPGLESRC) or WRKMBRPDM FILE(QRPGLESRC) to view member source.

10. RUNQRY doesn’t have find option. Any way out?

• Yes: Run RUNQRY with OUTPUT(*OUTFILE), then use DSPPFM on that outfile → now you can use F16=Find.

11. Can I pass a numeric variable for the call to a program from command line?

• No, only character values can be passed directly from command line.

• Numeric must be passed via CL variable or converted.

12. What command can be used to clear a physical file?

• CLRPFM FILE(MYLIB/MYFILE) → clears all records from PF.

13. Is it possible to have different descriptions for a source and its object?

• Yes. Source description (in source member) and object description (via DSPOBJD or CHGPGM) can be different.

14. Can I use CPYF command for copying a logical file?

• No, CPYF only copies data from physical files.

• For LF, copy must be from its underlying PF.

15. How can I know the dependent logical files on a physical file?

• Use: DSPDBR FILE(MYLIB/MYPF) → lists all dependent LFs.

16. Can I know the record count in a file using RUNQRY command?

• Yes: RUNQRY QRY(*N) QRYFILE((MYLIB/MYFILE)) with Summary function COUNT.

17. Can I select records from a file based on certain criteria using RUNQRY?

• Yes: RUNQRY allows selection criteria (e.g., field = value).

18. System creates job log when idle timeout occurs. How to always create job log?

• Set user profile/job description attribute: LOG(4 00 *SECLVL) so job log is always produced at signoff.

19. Is it possible to use SQL in CL programs?

• Yes, via RUNSQL command or RUNSQLSTM.

• Native embedded SQL is not supported in CL, only in RPG/COBOL.

20. Define a Batch Job.

• A job submitted using SBMJOB, runs in batch subsystem (QBATCH).

• Non-interactive, processed in background, scheduled via job queues.

✅ That’s 120 questions total (6 sets of 20) — an excellent prep library!

AS400 interview questions | Answers with explanation 20 questions | Part6