deibyz has asked for the wisdom of the Perl Monks concerning the following question:

Hello monks,

I'm working in an error report script that must send a mail to a mail group when any of the scripts associated to it fail. It's currently working, but I would like to add the script name that failed as the subject of the mail. The script is called with a system() call.

Is there any way to know the name of the caller process? (I'm working in an UNIX evironment) I've thought in passing name as a param, but this would mean change about 30 different scripts 8(.

Thanks in advance,
deibyz

Replies are listed 'Best First'.
Re: Parent process name
by Abigail-II (Bishop) on May 28, 2004 at 13:43 UTC
    On Linux and other Unix systems with a similar /proc filesystem: 
    my ($name) = `cat /proc/@{[getppid]}/cmdline` =~ /^(\S+)/

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    (This assumes you don't have sneaky program names with spaces in them).

    Abigail

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[d/l]
Re: Parent process name
by gsiems (Deacon) on May 28, 2004 at 13:48 UTC
    You mean something along the lines of: 
    
  #!/usr/bin/perl 

  use strict;
  use warnings;

  my $parent_id;

  foreach (`ps -ef`) {
     my ($uid,$pid,$ppid) = split;
     next unless ($pid eq $$);
     $parent_id = $ppid;
     last;
  }

  my $parent = (grep {/^\s*\d+/} (`ps -p $parent_id`))[0];

  my $parent_name = (split /\s+/, $parent, 5)[4];

  print $parent_name;

    [download]
    On my Linux box it outputs the following: 
      $ ./parent-process.pl
  bash
  $
[reply]
[d/l]
      Thanks a lot!

      It works with one little change:

      $ ps -p xxxx

  PID TTY          TIME CMD
29580 pts/4    00:00:00 bash

$ ps -p yyyy

   PID TTY      TIME CMD
  9556 pts/49   0:00 bash

      [download]
      See the blank space? Depending on it presence, I have to take the forth or the fifth elemnt of the last split. It works changing this line:
      my $parent = (grep {/^\s*\d+/} (`ps -p $parent_id`))[0];

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      With this:
      my $parent = " ".(grep {/^\s*\d+/} (`ps -p $parent_id`))[0];

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      Now I have at least one blank and have allways to take fifth element. Thanks again for the code.
      BTW, even if I work with UNIX, I must deal with different flavours (UNIX, Solaris, HP-UX...) and don't know if ps will output the same format everywhere (I'm going to test it).

      And the worst thing, I've just been told to make it run on Window$ 8( Is there anyway to get rid of the ps calls?

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[d/l]
[select]

        Good catch on the leading space ++

        "And the worst thing, I've just been told to make it run on Window$" Ouch!

        Well there's Win32::Process::Info for MS (which I have not used and know nothing about) and Proc::ProcessTable for unix (which I haven't used yet either), but they might be worth looking at.

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        Here's a windows version:

        use strict;
use Win32::Process::Info;

my $pihandle = Win32::Process::Info->new();
my @procinfo = $pihandle->GetProcInfo();

my $ParentPID;
my %ProcNames;

foreach my $PIDInfo (@procinfo) {
    $ProcNames{$PIDInfo->{ProcessId}} = $PIDInfo->{Name};

    if ($PIDInfo->{ProcessId} == $$) {
        $ParentPID = $PIDInfo->{ParentProcessId};
    }
}

print "Parent's name is ", $ProcNames{$ParentPID}, "\n";

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[d/l]

        An easier way to get the parent process ID would be to call the getppid() function.

        $parent_id = getppid();
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[d/l]
Re: Parent process name
by PodMaster (Abbot) on May 28, 2004 at 13:23 UTC
    You'll have to ask your operating system. Check CPAN. If PS can reveal that info for you, there is a module which parses PS output on CPAN.

    update: Unix::Process, Proc::ProcessTable...

    MJD says "you can't just make shit up and expect the computer to know what you mean, retardo!"
    I run a Win32 PPM repository for perl 5.6.x and 5.8.x -- I take requests (README).
    ** The third rule of perl club is a statement of fact: pod is sexy.

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