Under POSIX, the behavior of a program after an involuntary SIGSEGV is undefined. That means that you maybe can kill 11, $pid and catch it in the $pid process, but a genuine segfault may never return from whatever libc call generated it.

Setting signal handlers and capturing output are quite orthogonal. If you can do each, you can do both. I recommend piped ("magic") open for capturing output with a little more control than is given by backticks.

my $fh;
my $cpid = do {
    local $SIG{SEGV} = \&myhandler;
    open $fh, '-|', '/path/to/prog', @args or die $!;
};
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The perl script itself is the wrapper to the program. I have gotten to this stage now

#!/usr/bin/perl -w

use POSIX qw(:signal_h :errno_h :sys_wait_h);


$command = $ARGV[0];

parse();

if (!defined ($pid = fork()))
{
    die "cannot fork: $!";
}
elsif ($pid == 0)
{
    exec("$command");
}
else
{
    waitpid($pid, 0);

    if (WIFEXITED($?)) 
    {
        print "Exited\n";
    } 
    elsif (WIFSIGNALED($?)) 
    {
        $sig = WTERMSIG($?);
        if ($sig == 11)
        {
            print "Segfault\n";
            exit 11;
        }
        print "Signaled $sig\n";
    }
    else
    {
        print "EH\n";

    }
}
close STDOUT;
exit 0;


sub parse
{
    my $pid;
    return if $pid = open(STDOUT, "|- ");
    die "cannot fork: $!" unless defined $pid;
    
    while (my $line = <STDIN>)
    {
        print "$line";
    } 
    exit;

}
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So I am able to capture the program and take note of when it segfaults, and also parse the programs standard out. All I am missing now is capturing the programs stderr...

Apart from using IO::Capture is there another way that will simply add to the above code, or is this just wishful thinking?

Thank you very much to everyone who have replied to my question.

First, see if IPC::Open3 can do what you want. You would use it instead of fork and exec.

If it doesn't, you'll want to create filehandles for your child process with pipe, then assign them to STDIN, STDOUT, and STDERR after the fork, using POSIX::dup2 or similar.

Nope the program doesnt core dump, but thanks for your help.