AS400 Interview Questions - Part 2

AS400 Interview questions -  Part 2

Q1: Which library gets loaded first when we login to IBM i?

Answer:

• QSYS

Q2: How to see all the objects in the library and their size?

Answer:

• DSPLIB 

Q3: How to check all members of a file?

Answer:

• DSPFD <FILENAME> TYPE(*MBRLIST)

Q4: How to see all the record format in a file?

Answer:

• DSPFD <FILENAME> TYPE(*RCDFMT)

Q5: How to change the record size of a PF?

Answer:

• CHGPF SIZE(<changed Size>)

Q6: Why do we use the USROPN keyword in RPGLE?

Answer:

• To explicitly open a file in the RPG program.

Q7: Why do we use the EXTMBR keyword in RPGLE?

Answer:

• Override the file member.
• EXTMBR('Member Name')
• EXTMBR('ALL')

Q8: What is the purpose of using VARYING?

DVAR1             S             10A   VARYING
 /Free
  VAR1 = 'HELLO'; 
 /End-Free

Answer:

• To dynamically allocate the length.

Q9: What is CPF4131?

Answer:

• It's a Level Check Error.

Q10: Difference between CRTDUPOBJ and CPYF command?

Answer:

• CRTDUPOBJ will create the exact replica of an object such as LF would be LF.
• CPYF is used to copy data and it makes LF a PF.

Q11: What are mandatory keywords for a Subfile?

Answer:

• SFL (Subfile format keyword)
• SFLCTL (Subfile control format keyword)
• SFLDSP (Subfile Display keyword)
• SFLPAG (Subfile Page keyword)
• SFLSIZ (Subfile Size keyword)

Q12: What is the difference between PLIST ad KLIST?

Answer:

• PLIST is list of parameters.
• KLIST is list of key fields.

Q13: What is the difference between *INLR = *ON and RETURN?

Answer:

• RETURN will return the program to the caller.
• *INLR = *ON would free the memory and the program gets end.

Q14: What are the effective use and side effects of *INLR? How to overcome the side effects? Example use case scenarios?

Answer:

Effective Use:

• If *INLR = *OFF, return from called program, next call faster, program variable do not get reinitialized and program defined files do not get closed.

Side Effects:

• File stay open.
• Variable keep their values between calls.

Downside:

• File locking.

A better solution would be,

• Activation group use in ILE.
• Reclaim activation group.
• Ends all programs running in activation group.
• Files closed.
• Reinitialize all variables.
• No tracking is required, OS takes care of that.

Q15: What operations we can perform on Indicators?

Answer:

• SETON
• SETOFF

Q16: How to check if a record is locked in RPGLE?

Answer:

• *STATUS INFDS, Code 01218

Q17: How we can execute a CL command from within RPG program without calling a CL program?

Answer:

• QCMDEXC API
• QCAPCMD API
• SYSTEM API (C API)

Q18: Can we use a file with the same file name and same record format name in RPGLE?

Answer:

• No, but if we RENAME the record format name in F specs in RPG then Yes.

Q19: What are those commands which can only be executed in CL program but not in the RPG program?

Answer:

• CL commands starts with RTV*

Q20: How to retrieve the RRN value of the file record in RPGLE?

Answer:

• Using INFDS (file information data structure)

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