Greetings monks...

I have a Perl program which is an interactive shell style affair which is run by sshd on a remote server via sshd's ForceCommand. So I can ssh to one of my servers and I get to issue commands to my Perl program to run other Perl scripts which carry out system maintenance etc. It all works quite nicely. But if I want to tail -f a file like so...

if($cmd[0] eq "tail") {
    open(TAIL,"|tail -f /var/log/messages");
    while(<TAIL>) {
      print $_;
    } 
  }
}

[download]

... I need a way to break out of it. So I came up with this...

if($cmd[0] eq "tail") {
    open(TAIL,"|tail -f /var/log/messages");
    my $tailing = 1;
    sub __int_tail {
      $tailing = 0;
    }
    $SIG{'INT'} = \&__int_tail;
    while($tailing) {
      while(<TAIL>) {
        print $_;
      } 
    }
    return 0;
  }

[download]

... which works perfectly if I run if I run my Perl shell from a real shell. But if I ssh to my host the SIGINT gets captured by the ssh client on the local host.

So the question is, how do I capture or override SIGINT in a parent process that has forked (?) Perl? In fact, what even is the parent process in this case? sshd, a pseudo tty, my ssh client?

I guess this can be done because a real Unix shell in a ssh session can capture Ctrl-C issued locally and use it on the remote session.

Any wisdom would be most appreciated!

In reply to SOLVED Perl SIG INT handling conundrum. by differenceengine

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.