Perl syntax for sed searches

[masinick]

I am aware that Perl has a lot of features that originally came from sed and awk. I have a pattern that I am using like this:

sed -n '/|Y|/p'

I want to do the same thing in Perl and be able to either save that value in some kind of variable or array or potentially write it out to a file.

For the simple case, writing out to a file, I think the syntax is very close to the sed syntax. I would like to get a few recommendations , first, on a few alternative ways to write a similar expression in Perl, then how to do I/O properly.

My second question is that I have two files, both with pipe separated data. In the first file, I want to do a large data reduction first, taking the pattern above, and retaining only records containing |Y|. In the second file, I have a field containing an employee number with an A as the first digit. The other larger file contains this same data, but with a lower case a.

The complete exercise, then, is to first reduce the first file to records containing Y in the field, surrounded by the pipe symbol. Next, I need to compare the records that match in the second file to the employee ID field, after making sure it is lower cased in both files. I will need to print out two, possibly three fields within records that match, perhaps fields 1, 3, and 4.

Can anyone give me a few key technology snippets on this so I don't keep struggling with it, and I will then apply that technology to my modest sized application, which I am writing in Perl - for speed and portability. I have used Perl before, but I have never become an expert, and it has been years since I used it last. I am confusing myself with pieces of different syntax and making a lot of silly mistakes, therefore I would appreciate some sound advice to set me back on course. I am reading up using a few classics - the Perl Cookbook and Programming Perl, but both are large books and daunting to get through. Until I can digest them, I'd appreciate some pointers to accelerate my learning, and more importantly, get a script in at least a minimally usable form ASAP. Therefore, I appreciate specific tips. I'll get better at it once I have digested the classic resources and actually done more coding to regain the experience.

[masinick]

CLOSED: Program written, thank you very much!
Here is the final version (edited) of what I came up with:

#!/usr/bin/perl 
 
# File: MatchID.pl
# Author: Brian Masinick
# Initial Creation Date: August 1, 2008
 
 
# Inputs:
# M input feed file
# S input feed file
 
# Intermediate outputs:
# M output feed matching |Y|
 
# Final outputs:
# S output file matching records in M output file with those in S input file.
 
# Required software: Perl 5.10
 
open (MINPUT,"<M_input_file") || die("Could not open M_input_file");
open (MOUTPUT,">M_output_file") || die("Could not open M_output_file");
open (SOUTPUT,">Sl_output_file") || die("Could not open S_output_file");
 
# This produces the intermediate file, so we have a written record of which set
# of records we are actually processing to produce the final result.
 
while (<MINPUT>) {
   if ( /\|Y\|/ ) {
      print MOUTPUT;
   }
}
 
close (MINPUT,  M_input_file);
close (MOUTPUT, M_output_file);
 
print "M registered users recorded.\n";
 
open (MOUTPUT,"<M_output_file") || die("Could not open M_output_file");
 
while (<MOUTPUT>) {
        # split the input line into the @fields array
        @fields = split "[|]";
        # store the line in the %moutput hash indexed by the second field
        $moutput{$fields[1]}=$_;
}
 
 
open (SINPUT,"<S_input_file") || die("Could not open S_input_file");
 
print "Reading S users file.\n";
 
while (<SINPUT>) {
        # split the input line into the @fields array
        @fields=split "[|]";
        # if the fourth field exists in the %moutput hash, print the current
        # input line
        if (exists $moutput{$fields[3]}) { print SOUTPUT}
}
 
print "Processing complete.\n";
 
close (MOUTPUT, $MIIS_output_file);
close (SINPUT,  $Skytel_input_file);
close (SOUTPUT, $Skytel_output_file);
 
print "Files closed. Program complete.\n";