Re: Perl Term::ReadLine::Gnu Signal Handling Difficulties

[Mr. Muskrat]

Well, I have been setting up some new servers today (mounting them in the rack, running cables, etc) and haven't have much time to look at this.

I did find something interesting though. http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=160328 It seems that when Perl's safe signals were introduced, it broke Term::ReadLine::Gnu.

Do you need to use Term::ReadLine::Gnu or can you use Term::ReadLine::Perl (where this still works)?

If you do need it to use Term::ReadLine::Gnu then perhaps this will work for you. Beware though! It uses unsafe signals so it can cause all sorts of nasty things to happen to the Perl process. Oh and it seems to leave the terminal in an odd state when a signal forces it to bail out.

#!/usr/bin/perl
use strict;
use warnings;
BEGIN {
    $ENV{PERL_RL} = 'Gnu'; # or 'Perl' to force which one to use
}
use Term::ReadLine;
use Signal::Safety;

my $term = Term::ReadLine->new('Term1');
print "Readline: ", $term->ReadLine, "\n";
$term->ornaments(0);
my $attribs = $term->Attribs;
$attribs->{catch_signals} = 0;

$SIG{TERM} = sub { print "I got a TERM\n"; exit; };
$SIG{INT} = sub { print "I got a INT\n"; exit; };
# add any additional signal handlers you want

my $prompt = 'cmd> ';
my $cmd = '';
while ( defined $cmd ) {
    {
        local $Signal::Safety = 0; # limit the use of unsafe signals
        $cmd = $term->readline($prompt);
    }
    chomp($cmd);
    if ($cmd =~ /^help$/) {
        print "Help Menu\n";
    }
    else {
        print "Nothing\n";
    }
}

[sgt_b2002]

Thanks a ton for helping me out with this. I see what you mean about unsafe signals, so I'll probably just use Term::ReadLine::Perl instead. I suppose that solves my issues.

It is somewhat comforting to know that this is just how T:R:Gnu works instead of me doing horribly wrong. ;)

Since I'm sure I can get things moving along with T:R:Perl, what would be the best way to make sure users are using the T:R:Perl package instead of Gnu? Would it be considered good form to just set the environment variable along with a "use Term::ReadLine::Perl"?

Thanks again for taking the time to look into this. It was really a stumbling block for me so I appreciate the help. In hindsight I probably should have just moved to T:R:Perl and called it a day, but I got obsessed a bit. ;)

[Mr. Muskrat]

You're welcome!

Install Term::ReadLine::Perl and do what the module authors do when they test it.

BEGIN{ $ENV{PERL_RL} = 'Perl' };
use Term::ReadLine;