Need your help in a pattern based text manipulation algorithm

kaushik9918 has asked for the wisdom of the Perl Monks concerning the following question:

I am not an expert in Perl, hence requesting your help in this one. I have a user defined input which I need to parse and based on occurence of a pattern , need to replace certain lines on some text files based on the input file. So, for better understanding, I have got some text files , like a_copy.txt , a_paste.txt, a_cut.txt,b_copy.txt , b_paste.txt, b_cut.txt,c_copy.txt , c_paste.txt, c_cut.txt,d_copy.txt , d_paste.txt, d_cut.txt . Basically, my user input file looks like this:

NAME|VALUE = a
TASK|VALUE = copy
CAPS|VALUE = 0
PKG_TYPE|VALUE = premium

NAME|VALUE = z
TASK|VALUE = cut
CAPS|VALUE = 0
PKG_TYPE|VALUE = premium

NAME|VALUE = c
TASK|VALUE = paste
STACK|VALUE = 2
SHIP|VALUE = lowtier
[download]

Now , based on the input file, I first have to parse and if "NAME|VALUE = a" and the corresponding "TASK|VALUE = copy" , it should open a_copy.txt (if a_copy.txt doesn't exist, throw an error and exit, which is easy). Inside a_copy.txt, it has to check if the following lines with starting keywords like the input , i.e,

CAPS|VALUE = 
PKG_TYPE|VALUE =
[download]

exist and replace them in the a_copy.txt file with the input file values of "CAPS|VALUE = 0" and "PKG_TYPE|VALUE = premium". Any empty line in the input file should be ignored.

It should do this for all the text files corresponding to all the "NAME|VALUE = ??" and the corresponding "TASK|VALUE = ??" and replace all lines in the correct text file based on the input file values

I have managed to write a code which parses the input file for any format differences etc and report out, but I am stuck in writing the subroutine to do the replace the input file lines in the text files. My code is (although incomplete) is :




use Tk;
use IO::Handle;


#################### Check for correct usage of script################
+############

$mw = new MainWindow;


my $num_args = $#ARGV +1 ;
if ($num_args != 0) 
{
   
   $mw -> messageBox(-message=>"\nUsage: perl replay_file_changes.pl\n
+");
   exit;
}
######################################################################
+############



###################### User input ####################################
+#############################
print "\nPLEASE SPECIFY INPUT FILE\n";
$ip_file = <>;
chomp $ip_file ;
#check validity of user input
if (-e $ip_file){
    }
else{
    $mw -> messageBox(-message=> "\n$ip_file IS NOT FOUND\n");
    exit;
    }
######################################################################
+############################






###################### Real deal #####################################
+############################


open(INPUT_FILE, "<$ip_file")  || die "\n!!!ERROR OPENING INPUT FILE. 
+EXITING SCRIPT!!!\n";



while(<INPUT_FILE>){
        
        
        
        if ($_=~ /(.*) =\n/ ){
                            
                            $mw -> messageBox(-message=> "\nFormat not
+ correct on line $. of input file. Exiting script\n");
                            exit;
                        }
        elsif ($_=~ /(.*) =\s+\n/ ){
                            
                            $mw -> messageBox(-message=> "\nFormat not
+ correct on line $. of input file. Exiting script\n");
                            exit;
                        }
        elsif ($_=~ /(.*) = \s+(.*)/ ){
                            
                            $mw -> messageBox(-message=> "\nFormat not
+ correct on line $. of input file. Exiting script\n");
                            exit;
                        }
        
        
        elsif ($_=~ /^NAME\|VALUE = (.*)/ ){
                            
                            
                            &check();
                            }
        
        }
        



sub check {
        
        #print "\n$cell_name\n";
        my $name= $1;
        chomp $name;
        while(<INPUT_FILE>){
                    if($_=~ /^TASK\|VALUE = (.*)/){
                                            
                                        $task_value= $1;
                                    }
                    elsif($_=~ /^(.*) = (.*)/){
                                            
                                        $line=$_;
                                    }                        
                    elsif($_=~ /^NAME\|VALUE = (.*)/){
                                            
                                        exit;
                                    }                        
                                            
                                            
                print "\n$name $task_value $line\n";    
                    
                    
                    
                                            }
                    }
[download]

And my output is:


a copy 

a copy CAPS|VALUE = 0


a copy PKG_TYPE|VALUE = premium


a copy PKG_TYPE|VALUE = premium


a copy NAME|VALUE = z


a cut NAME|VALUE = z


a cut CAPS|VALUE = 0


a cut PKG_TYPE|VALUE = premium


a cut PKG_TYPE|VALUE = premium


a cut NAME|VALUE = c


a paste NAME|VALUE = c


a paste STACK|VALUE = 2


a paste SHIP|VALUE = lowtier
[download]

Can someone please help me with subroutine to do the job here? PLease dont hesitate to ask if you got any further questions on this, Regards

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