Some extra options to DBUG_PUSH:

O,logfile   - As in "o,logfile", but do a close and reopen each time anything
	      is written to the logfile. This is needed when one expects
	      the program to crash anywhere, in which case one doesn't
	      (at least in MSDOS) get a full log-file.

If one wants a logfile with a ':' in the filename, one can get it by
giving a double ':'.  (As in "O,c::\tmp\log")

DBUG_DUMP("keyword",memory-position,length) writes a hexdump of the
given memory-area to the outputfile.