Regular expressions

user786 has asked for the wisdom of the Perl Monks concerning the following question:

I have written a function which is in a library, and I call the functions from my test script.

The function returns 0.

ideally it should return Starting strongSwan 5.1.2 IPsec

I checked the regular expression in https://regex101.com/ . My regex seems to be correct. /(Starting strongSwan.*IPsec$)/ .

Can somebody help me out with the return value of the function.

Function :

 sub ipsec_restart {

    my ($self) = @_;
    my $cmd = 'sudo -s ipsec restart';
    my $restart = 0;

    $self->execute($cmd);

    foreach my $line ( @{ $self->get_stdout() } ) {
     if ( $line =~ /(Starting strongSwan.*IPsec$)/ ) {
          $restart = $1;
          last;
        }
    }

    return $restart;
}
[download]

Function call :

 $self->{'ipsec_restart'} = $self->{'ipsec_obj'}->ipsec_restart();
      ('[Startup] ipsec restart status  is  : '  .  $self->{'ipsec_res
+tart'} );
[download]

Expected output : See the highlighted text below.

Starting strongSwan 5.1.2 IPsec Actual output is : 0

Comment on Regular expressions Select or Download Code

Replies are listed 'Best First'.
Re: Regular expressions by RichardK (Parson) on Apr 10, 2015 at 18:11 UTC
Are you 100% sure that $self->get_stdout() is returning what you expect it to return? (Did you forget to chomp?) Try adding `print '<',$line,">\n";` to the start of the foreach loop. Also see Basic Debugging Checklist for lots of other suggestions on how to debug any problem.	[reply] [d/l]
Re: Regular expressions by GotToBTru (Prior) on Apr 10, 2015 at 18:10 UTC
Do you know what the contents of $line is when you apply your regex? Dum Spiro Spero	[reply]
Re^2: Regular expressions by user786 (Sexton) on Apr 10, 2015 at 18:16 UTC
Stopping strongSwan IPsec... Starting strongSwan 5.1.2 IPsec starter...	[reply]
Re^3: Regular expressions by GotToBTru (Prior) on Apr 10, 2015 at 18:19 UTC
The $ at the end of your regex says it should match up to the end of the string. If anything (including a space) is appearing after "IPsec", then the string doesn't end with "IPsec" and the match will fail. Remove the $, and it should work. Dum Spiro Spero	[reply]
Re^4: Regular expressions by Anonymous Monk on Apr 10, 2015 at 19:23 UTC
Re: Regular expressions by NetWallah (Canon) on Apr 10, 2015 at 18:19 UTC
You are making the assumption that all the output you see when you run "ipsec restart" from a console comes from a single process. My (very limited) understanding of strongSwan is that it uses a "starter" process which forks out a thread to do the actual work. I think you are capturing the output of the "starter" process, and missing the actual ipsec messages. You can confirm my theory by examining the console messages after running your program - if you see the "Starting strongSwan" on the cosole, it means that your code did not capture it. "You're only given one little spark of madness. You mustn't lose it." - Robin Williams	[reply]
Re: Regular expressions by ww (Archbishop) on Apr 10, 2015 at 20:06 UTC
Just in case this is 'new' info for you, the "`.`" (fondly known as 'dot splat') in `$line =~ /(Starting strongSwan.IPsec$)/` will match ZERO or more instances of ANY char except a newline. The asterisk is a quantifier (NOT A WILDCARD; that's the dot). For more, see perldoc.perl.org/perlre.html or type (at your console) `perldoc perlre` (or if you need to `perldoc perlretut`) and similar. Spirit of the Monastery	[reply] [d/l] [select]


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