When cracking a passwd file, john saves a file called "restore" in
the current directory that marks where the program is in the cracking
process.  The "-restore" flag can be used to resume an aborted session
rather than starting over from scratch.  However, if john is run again
on the same passwd file without the "-restore" flag being used, the
restore file will be overwritten with a new one, and all work done in
the previous session will be lost as the cracking process is started
again from scratch.  I believe this is counterintuitive, because there
are very few instances in which a user would desire to start over from
scratch rather than resuming the previous session.

This is especially painful after running john for over a week,
terminating it for a few minutes, then starting it again only to
discover that the program is starting from scratch.  I believe that
before starting a session from scratch, john should check for the
existence of a restore file, and if the restore file exists, do one
of two things:

1.  Notify the user that the restore file exists, and ask if the user
would like to resume the session.

2.  Rename the old restore file to restore.old before creating a new
one, so that all the work done in the previous session is not lost.

The problem is compounded by the lack of a man page, an info page,
"-h" or "--help" options, or consise documentation.