G'day cspctec,

I'd read through the ps output adding key-value pairs to a hash with this format: 

PID => [ PPID, COMMAND ]

[download]

At the same time, adding any '<defunct>' pids to an array.

Then, it's a simple matter to iterate the array of defunct pids and generate the trace from the data in the hash. Here's the sample code (which handles multiple defunct pids): 

#!/usr/bin/env perl

use strict;
use warnings;

my (%ps_data, @defunct_processes);

while (<DATA>) {
    next if $. == 1;  # Skip header: 'PID PPID COMMAND'
    chomp;
    my ($pid, $ppid, $cmd) = split ' ', $_, 3;
    $ps_data{$pid} = [$ppid => $cmd];
    push @defunct_processes, $pid if $cmd eq '<defunct>';
}

for my $pid (@defunct_processes) {
    my @trace;

    while ($pid >= 1) {
        push @trace, [$pid, @{$ps_data{$pid}}];
        $pid = $ps_data{$pid}[0];
    }
   
    printf "%4d  %4d  %s\n", @$_ for reverse @trace;
}

__DATA__
 PID  PPID  COMMAND
   0     0  sched
   1     0  /sbin/init
   7     0  vmtasks
 105     1  /usr/lib/saf/sac
7184     1  /usr/bin/java
7222     1  /usr/lib/utmpd
7501  6223  /usr/sbin/nscd
7507  7184  /bin/sh
7508  7507  /usr/bin/perl
7510  5044  /usr/bin/grep
7512  4333  /usr/bin/egrep
7515  7508  sh
7516  7515  <defunct>

[download]

Output:

   1     0  /sbin/init
7184     1  /usr/bin/java
7507  7184  /bin/sh
7508  7507  /usr/bin/perl
7515  7508  sh
7516  7515  <defunct>

[download]

Note that the split command uses a LIMIT of 3. This allows '/path/with spaces/to/command' to be captured in full; without that, you'd only capture '/path/with'.

— Ken

In reply to Re: Help parsing this data by kcott
in thread Help parsing this data by cspctec

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