💬 Q&A Solutions

NULLFILE is alternate for DUMMY. //DD DD NULLFILE. Discards output, provides EOF for input. DSN=NULLFILE equivalent. No actual dataset. Useful for testing without actual files.

DD DUMMY discards output/provides EOF for input. No I/O actually performed. DUMMY, DSN=NULLFILE equivalent. Use to skip optional outputs or provide empty input. Program sees immediate EOF on read. Writes succeed but discarded.