what —
search files for SCCS identifiers
The what utility reads each file
  operand and searches for sequences of the form “@(#)” as
  inserted by SCCS and SCCS-compatible version control systems. It prints the
  remainder of the string following this marker, up to a null character,
  newline, double quote, backslash, or “>” character.
If the -s option is specified, only the
    first occurrence of an identification string in each file is printed.
The what utility exits 0 if any matches were found, and
  1 otherwise.
The what utility conforms to X/Open
  Portability Guide Issue 4, Version 2
  (“XPG4.2”).
The what command appeared in
  4.0BSD.
As BSD is not licensed to distribute SCCS this is a
  rewrite of the what command which is part of SCCS, and
  may not behave exactly the same as that command does.