my $cust_code  = “SILICONEXSiliconex-wafers”;

my $pattern = "SILICONEX((?i)siliconex-wafers)";
if ($cust_code =~ /$pattern/){

                               print "[$&]\n";

                             }
__END__
[SILICONEXSiliconex-wafers]


##</code><code>##


my $pattern = "(?i)SILICONEXsiliconex-wafers";
if ($cust_code =~ /$pattern/){

                                 print "$&\n";

                             }


##</code><code>##



• a  pattern that is searched with a certain flag for a part of the pattern and that which has no flags in the pattern
• to sub-group the pattern and effectively use flags of

     (?m) as /m for mult-line strings,
     (?s) as /s for single line strings,
     (?x) as /x for extended search including comment lines  and space delimiters and 
     (?i) as /i for case sensitive pattern notation 
          or a combination of the flags


##</code><code>##


my $sub_contract="SILICONEXsiliconex-wafers ^M NOTE1-- a shipment in ^M backlog calc note for 
the shipping dates the contract is delivered ";

my $pattern = "SILICONEX((?i)siliconex-wafers)";
                                       

if ($sub_contract =~ /$pattern/)
{

     $sub_contract =~ s/(?m:(\^M|--))/ /g;   
     my ($shipment_note, $sub_contract_keynote ) = 
          reverse split(/(?i)NOTE/ ,$sub_contract);
     print "[ $sub_contract_keynote ] [ $shipment_note ]\n";
          
}

__END__

[ for 
the shipping dates the contract is delivered ] [ 1 a shipment in  backlog calc note ]


##</code><code>##

    s/(?m:(\^M|--))/ /g 
##</code><code>##


(?=     indicates a positive forward(look_ahead) assertion
(?!     indicates a negative forward(look_ahead) assertion
(?<=    indicates a positive backward(look_behind) assertion
(?<!    indicates a negative backward(look_behind) assertion


##</code><code>##

     $product = "MOTOROLAx|xx|xx|x01-01-1900x|xYx|x";
     $product =~ s/x\|xx\|x/x\|x x\|x/g;
     print "[ $product ]\n";
     __END__

     [ MOTOROLAx|x x|xx|x01-01-1900x|xYx|x ]


##</code><code>##

 [ MOTOROLAx|x x|xx|x01-01-1900x|xYx|x ]
##</code><code>##

$product = "MOTOROLAx|xx|xx|x01-01-1900x|xYx|x";
$product =~ s/(?<=\|)xx(?=\|)/x x/g;
print "[ $product ]\n";
__END__

[ MOTOROLAx|x x|x x|x01-01-1900x|xYx|x ]


##</code><code>##

$product = "MOTOROLAx|xx|xx|x01-01-1900x|xYx|xx";
$product =~ s/(?<=\|)xx(?=(\||$)/x x/g;
print "[ $product ]\n";
__END__


[ MOTOROLAx|x x|x x|x01-01-1900x|xYx|x x ]