[mythtv-users] Fully delete rec from cli

[f-myth-users at media.mit.edu]

The easiest way I've found to do deletions is to pretend I'm a web
client.  In other words, I went to the Recorded Programs page in a
browser and dumped the page source.  You'll find that there are
non-Javascript links (for supporting browsers which have JS turned
off) on the page.  In 0.18.1, they're of the form
  http://host/mythweb/recorded_programs.php?delete=yes&file=filename
where "host" and "filename" should be substituted as appropriate.

I have automation that deletes programs, it just does something like
  wget -O /dev/null -a logfile -q http://....

Yeah, yeah, it'd be cleaner to send a message using the Myth protocol
to the backend, or delete the file myself and then diddle with the
database -and still- send a message so any frontends get their state
updated, but the Mythweb approach was really, really straightforward,
and it insulates me from the underlying details of the implementation
---no matter -what- Myth does, I can be pretty confident that Mythweb
of the matching version will still be able to delete files.  And if
the URL that Mythweb uses changes, that's a quick fix.  (And there's
no standalone client to send arbitrary Myth-protocol messages, and I
didn't feel like writing one.)

Note:  For the first couple of months, files vanished instantly (this
is on a JFS filesystem, and again remember that I'm using 0.18.1 so
there's none of this incremental-delete stuff going on).  For some
reason I've never figured out, things suddenly changed such that it now
takes 5-6 seconds for the actual filename to vanish from the filesystem.
Yes, the database is optimized & the FS is healthy, yadda yadda.  Since
my automation does error-checking by ensuring that the file really
-does- vanish before it moves onto the next (in part to guard against
errors, and in part not to totally pound mythweb & mysql into the
ground), I had to put a short loop in that checks once a second until
the file actually disappears.  It typically takes 5-6s; the script
would alarm if it took more than 30, but it hasn't.  (And I do mean
"suddenly"; what -was- sub-second jumped discontinuously to 5+ seconds.
It wasn't some gradual bit-rot sort of slowdown.  The machine's
configuration hadn't been touched in weeks; in fact, it hadn't even
been -booted- for several days before that.  Mythweb returns almost
immediately (e.g., the wget terminates fast); it then takes 5-6s after
-that- for the file to go away.  Mythweb is running on the MBE, and
the files sit directly there; while there are NFS mounts on the
machine, the actual video directory is local and not NFS-mounted.)

P.S.  The existence of these delete links is why it's so vitally
important to make sure that your Mythweb is protected from access
by any untrusted host or browser (including -yourself- running a
wget with the wrong URL and a recursive retrieval option).  Otherwise,
even an innocent spider will delete all your recordings.