[Toybox] ps -t is cheating.

[Rob Landley]

So posix says this:

-t  termlist
  Write information for processes associated with terminals given in
  termlist. The application shall ensure that the termlist is a single
  argument in the form of a <blank> or <comma>-separated list. Terminal
  identifiers shall be given in an implementation-defined format. [XSI]
  [Option Start]  On XSI-conformant systems, they shall be given in one
  of two forms: the device's filename (for example, tty04) or, if the
  device's filename starts with tty, just the identifier following the
  characters tty (for example, "04" ). [Option End]

And once again posix is somewhere back before the 1980's because
pseudo-terminals do not start with "/dev/tty". In the case of linux,
they've been /dev/pts/12 since, apparently, 1998.

The ps man page says:

  -t ttylist
       Select by tty.  This selects the processes associated with the
       terminals given in ttylist.  Terminals (ttys, or screens for
       text output) can be specified in several forms: /dev/ttyS1,
       ttyS1, S1.  A plain "-" may be used to select processes not
       attached to any terminal.

Which is, once again, outright lying, because "-t 41" matches pts/41 but
-t 5 does _not_ match tty5. You have to say "-t tty5" to get the getty
instance on there.

Meanwhile procutils "ps -t pts/41" works as does "ps -t pts/../tty5"
which is just _creepy_ and I'm not doing that bit. And -tty S0 is of
course /dev/ttyS0 not /dev/pts/S0.

I pine for a spec that means something,

Rob

P.S.  Once again, the hard part is writing help text so ps --help can
explain the expected behavior succinctly. Yeah, I can do that, but how
do I explain it in a way that makes it sound intentional: -t ## is a pts
(unless maybe there isn't one? Does it fall back to tty5 if there's no
pts5? Hard to test right now because I've got /dev/pts/68 but only
/dev/tty63). Grrr. STOP TRYING TO BE CLEVER IN WAYS YOU DON'T EXPLAIN TO
YOUR USERS IN THE MAN PAGE. Right special case "-t number" to be pts/
instead of tty, accept pts/ to _not_ mean implicit tty prefix...

 1445231357.0