what is the 'what' command on AIX under LINUX
The what command is part of the Source Code Control System (SCCS), which is not commonly available on Linux (if there is a Linux version at all). You can try to emulate it with the strings command:
strings a.out | fgrep '@(#)'Reimplementations of what are available in CSSC (an SCCS-to-modern version control conversion package) and in BSD (source code).