FirstLine 
newline1:FieldCostant1,value1:FieldCostant2,value2:FieldCostant3,value3 
newline2:FieldCostant1,value1:FieldCostant2,value2:FieldCostant3,value3 
newline3:FieldCostant1,value1:FieldCostant2,value2:FieldCostant3,value3 
....

 open (PARSEFILE, "<", $FileToParse); 
while ($FileTemp = <PARSEFILE>){ 
if ( $FileTemp =~ \.\s+\w+\s+/FieldCostant1,\s(T\d+)$/) { 
     print $FileTemp; 
} 
} 
close (PARSEFILE);

$FileTemp =~ m[...] 

substr EXPR, OFFSET [ , LEN ]

my $value = substr $line, 24, 30; # (if I counted the characters right...)

my $line = "newline1:FieldCostant1,value1:FieldCostant2,value2:FieldCostant3,value3"; 
my ($field_1, $field_2) = split /:/, $line ; #$field_2 is now  "FieldCostant1,value1" 
my ($cst1, $value1) = split /,/  $field_2;

my $value1 = $1 if $line =~ /^\w+:\w+,(\w+)/;

     open (PARSEFILE, "<", $FileToParse) or die "No file!"; 
while ($FileTemp = <PARSEFILE>){ 
my ($field_1, $field_2) = split /:/, $FileTemp; 
my ($cst1, $value1) = split /,/, $field_2 ;print "$value1\n"; 
} 
close (PARSEFILE);

  $FileTemp =~ s/:/\n/g;  
my $value1 = $2 if $FileTemp =~ /^TRANSID,\w+/;  
print $value1;

 $FileTemp =~ s/:/\n/g; 
my $value1 = (/^STRING,\w+(\w+)/), $FileTemp; 
print $value1;

use strict; 
use warnings FATAL => qw(all);

Global symbol "$FileToParse" requires explicit package name at BatchParser.pl line 8. 
Global symbol "$FileParsed" requires explicit package name at BatchParser.pl line 11. 
Global symbol "$FileToParse" requires explicit package name at BatchParser.pl line 29. 
.... 
Execution of C:\Users\ADS\Desktop\Perl_Test\BatchParser.pl aborted due to compil 
ation errors.

Global symbol "$FileTemp" requires explicit package name at BatchParser_2.pl line 7. 
Global symbol "$FileTemp" requires explicit package name at BatchParser_2.pl line 8. 
syntax error at BatchParser_2.pl line 8, near "){" 
Global symbol "$FileTemp" requires explicit package name at BatchParser_2.pl line 9. 
Global symbol "$FileTemp" requires explicit package name at BatchParser_2.pl line 10. 
syntax error at BatchParser_2.pl line 12, near "}" 
Execution of BatchParser_2.pl aborted due to compilation errors.

 
use strict;  
use warnings FATAL => qw(all); 
 
my $FileToParse="C:/Users/Me/Desktop/Perl_Test/temp/File.log"; 
open (PARSEFILE, "<", $FileToParse) or die "No file!!!"; 
$FileTemp="x" 
while ($FileTemp = <PARSEFILE>){ 
$FileTemp =~ s/:/\n/g; 
my $value1 = (/^STRING,\w+(\w+)/), $FileTemp; 
print $value1; 
} 
close (PARSEFILE);

use strict;  
use warnings FATAL => qw(all); 
use diagnostics; 
 
my $FileToParse="C:/Users/me/Desktop/Perl_Test/temp/File.log"; 
open (PARSEFILE, "<", $FileToParse) or die "No file!!!"; 
#$FileTemp="x" 
while ($main::FileTemp = <PARSEFILE>){ 
$main::FileTemp =~ s/:/\n/g; 
#my $value1 = (/^STRING,\w+(\w+)/), $main::FileTemp; 
#print $value1; 
print $main::FileTemp; 
} 
close (PARSEFILE);

Uncaught exception from user code: 
Useless use of a variable in void context at BatchParser_2.pl line 11

$FileTemp="x"

my $FileTemp="x" ;

 
use strict; 
use warnings FATAL => qw(all); 
#use diagnostics; 
 
my $FileToParse="C:/Users/me/Desktop/Perl_Test/temp/File.log"; 
open (PARSEFILE, "<", $FileToParse) or die "No file!!!"; 
my $FileTemp="x"; 
while ($FileTemp = <PARSEFILE>){ 
$FileTemp =~ s/:/\n/g; 
my $value1 = (/^TRANSID,\w+(\w+)/), $FileTemp; 
print $value1; 
} 
close (PARSEFILE);

Useless use of private variable in void context at BatchParser_2.pl line 11

my $value1 = (/^TRANSID,\w+(\w+)/), $FileTemp;

my $value1 = $1 if $FileTemp =~  /^TRANSID,\w+(\w+)/;

use strict; 
use warnings FATAL => qw(all); 
#use diagnostics; 
 
my $FileToParse="C:/Users/me/Desktop/Perl_Test/temp/File.log"; 
open (PARSEFILE, "<", $FileToParse) or die "No file!!!"; 
my $FileTemp="x"; 
my $value1="x"; 
while ($FileTemp = <PARSEFILE>){ 
$FileTemp =~ s/:/\n/g; 
print $FileTemp; 
#print my $value1 = $2 if $FileTemp =~ /^(TRANSID),(\w+)/; 
#print $value1; 
} 
close (PARSEFILE);

LOG 
T1,ValueT 
TRANSID,valueNeeded 
OTHER,parameters;