Hi PerlMonks,

I chanced upon this discrepancy in pattern matching behavior. I don't understand the reason for which i seek assistance.

When using multiple alternation meta characters across multiple lines in a single regex , not all the patterns are correctly matched.

The code below does not work

#!/usr/software/bin/perl

my $output = "Error: Illegal option -- x";

print "\nTRUE\n"
    if ( $output
    =~ /The.*?command\stakes.*?arguments;\syou\sgave.*
        |Illegal\soption.*
        |.*?is\snot\sa\svalid\soption.*/i
    );
[download]

whereas the same works when the alternation meta characters are in a single line

#!/usr/software/bin/perl

#my $output = `dfm event list  -x`;

my $output = "Error: Illegal option -- x";

print "\nTRUE\n"
    if ( $output
    =~ /The.*?command\stakes.*?arguments;\syou\sgave.*|Illegal\soption
+.*|.*?is\snot\sa\svalid\soption.*/i
    );
[download]

Baffled.