Question { 12220 }

where we give the MSGSFL in rpg400?

Answer

you will not declare/give your MSGSFL in the RPG pgm.
It will be declared(or more precisely included) in the DSPF, at the bottom; used by your RPG program.

Search for sp. K/words like SFLMSGRCD, SFLMSGKEY, SFLPGMQ in the DSPF; that's your MSG Subfile.

Question { Four soft, 9349 }

what is the intractive job? what is the batch job ?
how to change the batch job to interactive job?

Answer

When you sign-on an AS/400 system, you are interacting with
interactive jobs(e.g.QINTER). The System-jobs which are
presubmitted are called batch jobs(e.g.QBATCH, QSPL, QCMN etc.,)

If u want to know whether a job is in Interactive or Batch,
u can use RTVJOBA command with attribute JOB-TYPE on that job.
if it has a value '1' = Interative; '0' = Batch.

you can change a Batch-job to Interactive-job as long as it
is in JOBQ(by changing the environment on CHGJOB(opt-2)
command to QINTER or QPGMR); once it's active we cannot
change the type.

Question { 8006 }

How do I link an existing logical file to it's Physical
File without recompiling?

Answer

The above answer is correct, but why do u want to link the LF?
It is already based on the PF only(a view on PF only).
Unless u have changed the LF, u dont need to use CHGLF.