On Tue, 14 Oct 2008, Mark Eichin wrote:
Peder Stray <[EMAIL PROTECTED]> writes:
On Tue, 14 Oct 2008, Trent W. Buck wrote:
"Sven Hazejager"
<[EMAIL PROTECTED]> writes:
I'm using screen to keep some applications open over a remote SSH
connection that sometimes is killed. What I would like to do, is to
somehow find out whether I am logged in (attached) or disconnected
from the screen session.
Reason is that I want procmail to send incoming mail to my BlackBerry
if I'm disconnected, but NOT do that when I'm SSH-ing into my Pine
session.
I don't know how to achieve that, but perhaps there's a different
approach to the problem -- such as always forwarding all mail to an
IMAP server that you can access from both the blackberry and from
pine.
The screen-socket has execute permissions when attached, and none when
detached, like this:
attached:
ls -l /tmp/uscreens/S-peder/4598.irc
prwx------ 1 peder peder 0 Oct 14 00:00 /tmp/uscreens/S-peder/4598.irc
detached:
ls -l /tmp/uscreens/S-peder/4598.irc
prw------- 1 peder peder 0 Oct 14 07:06 /tmp/uscreens/S-peder/4598.irc
Guess you can test for that i procmail by something like:
:0c
*? perl -e 'exit ! grep { (stat $_)[2] & 0100 } </tmp/uscreens/S-peder/*>'
[EMAIL PROTECTED]
Parsing "screen -ls" output (for "Attached" or not) might be less
sensitive to implementation details, but that's a pretty clever test...
I'm not familiar with procmail, but it might be cleaner to use
! test -x /tmp/uscreens/S-peder/*
(to avoid starting perl on every message - I think both of these assume
there's only one socket that matches the rule, though it's pretty easy
to change if not...)
True, perl is bigger than test, but i guess you mailserver should be real
slow for you to actually notice :) The perl test actually checks for any
attaced screen, so it should work for cases where there is more than one
socket in the dir. Using the test-line as above would break violently in
that case since it expect only one argument. Parsing the output from
screen -ls would of course be even more expensive that either perl or
test.
Of course, all of this expects that screens tmp-dir is available on the
mailserver, which it may not be. In that case, it may be easier to make a
wrapper for screen that touches a statusfile before starting screen and
maybe doing the perl-test after and remove the file if no screens are
attached (so you actually can attached more than once to the screen)
--
Peder Stray
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