Change your grep to do something useful.

my @keepers = grep /^$match$/, @lines;
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...for instance. The problem with your existing code is that $match, used as a simple expression, is simply evaluated in boolean context; if $match contains a value that Perl considers true, the expression will be true. Since "AZ", the string, is always true, every @lines gets grepped into @keepers.

G'day PerlSufi,

In a boolean context, any non-zero-length string evaluates to TRUE. So the grep expression will always be TRUE and @keepers will be a copy of @lines.

$ perl -Mstrict -Mwarnings -E '
    my $match = "AZ";
    my @lines = qw{AZ SX AZ DC};
    my @keepers = grep { $match } @lines;
    say "@keepers";
'
AZ SX AZ DC
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What you need to do to filter @lines, is make the grep expression a regular expression (i.e. /$match/).

$ perl -Mstrict -Mwarnings -E '
    my $match = "AZ";
    my @lines = qw{AZ SX AZ DC};
    my @keepers = grep { /$match/ } @lines;
    say "@keepers";
'
AZ AZ
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this worked

my $match = "AZ";
my $content = $mech->content; 
my @lines = split /^/, $content;
my @keepers = grep {/\Q$match\E/}  @lines;
print @keepers;
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Thanks for the response, Ken. That is helpful how you explained it. However, should I make the $content an array of lines to match? I have taken out the foreach operator right now..

Splitting the lines to create an array is probably what I would have done. However, if you want to work directly with a multiline string, here's one way to do it:

$ perl -Mstrict -Mwarnings -E '
    my $lines = "AZ\nSX\nAZ\nDC\nAB\nYZ\n";
    say $lines;
    $lines =~ s/(?>[^A].|.[^Z])\n//gm;
    say $lines;
'
AZ
SX
AZ
DC
AB
YZ

AZ
AZ
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In my opinion, the multiline solution is a lot more cryptic than the array solution.

-- Ken