The most recent player commands are kept in the global array
player_commands[], which is indexed by player_commands_index.  Array
elements are strings of the form:

  "%3d %3d %s", index, player->cnum, command

When the player is prompted, then [prompt] is inserted as command.

The server tries to log the most recent player commands when it
crashes.

When the server detects a problem, it logs it and tries to recover.
The code is being converted to call oops() for this purpose, commonly
through CANT_HAPPEN().  When you run the server with -d, oops()
crashes by calling abort() before the recovery.  This is what you want
when you run it in a debugger.