The line with barney in it has whitespace at the beginning so /^barney/ won't match.

$_ = 'This is a wilma line
       barney is on this line
       but this line ends with fred
       and a final dino line' ;
      
if (/^barney/m) { 
  print "Found barney \n";
} else {
  print "Barney not found \n";
}

$_ = 'This is a wilma line
barney is on this line
but this line ends with fred
and a final dino line' ;
      
if (/^barney/m) { 
  print "Found barney \n";
} else {
  print "Barney not found \n";
}

__END__

Outputs:

Barney not found
Found barney
[download]

Hi

There is no line that begins with 'barney'

There is a line that begins with '         barney'

https://metacpan.org/pod/re#%27debug%27-mode explains

$ perl -Mre=debug barney
Compiling REx "^barney"
Final program:
   1: MBOL (2)
   2: EXACT <barney> (5)
   5: END (0)
anchored "barney" at 0 (checking anchored) anchored(MBOL) minlen 6
Guessing start of match in sv for REx "^barney" against "This is a wil
+ma line%n         barney is on this line%n     "..
.
Found anchored substr "barney" at offset 30...
Found /^/m, restarting lookup for check-string at offset 53...
Did not find anchored substr "barney"...
Match rejected by optimizer
Barney not found
Freeing REx: "^barney"
[download]

Hello catfish1116,

Other monks have shown you where the problem lies, but (strangely) no-one has made the fix explicit: change the regular expression from /^barney/m to /^\s*barney/m. This says: match any line beginning with zero or more whitespace characters followed by “barney”.

Perhaps it will make things a little clearer if we break the string into lines, and apply the regex to each line in turn:

use strict;
use warnings;

my $para = 'This is a wilma line
         barney is on this line
         but this line ends with fred
         ** this line has barney in the middle **
         and a final dino line';

my $count = 0;

for my $line (split /\n/, $para)
{
    printf "line %d: >%s< -- barney %sfound\n", ++$count, $line,
            $line =~ /^\s*barney/ ? '' : 'not ';
}
[download]

Output:

13:49 >perl 1958_SoPW.pl
line 1: >This is a wilma line< -- barney not found
line 2: >         barney is on this line< -- barney found
line 3: >         but this line ends with fred< -- barney not found
line 4: >         ** this line has barney in the middle **< -- barney 
+not found
line 5: >         and a final dino line< -- barney not found

13:49 >
[download]

(Of course, when we know we’re dealing with a single line at a time, the /m modifier is no longer needed on the regex.)

Hope that helps,

Socratic not spoon :)