Shell Programming and Scripting

#!/usr/bin/env perl
use strict;
use warnings;

# Bail out if no file is given as an argument.
my $ldap_file = shift || usage();

# To save output with extension .csv.
my $csv_file = "$ldap_file.csv";

# Preserve order of header labels.
my @header = qw(uid0 givenname salesorg sn telephonenumber l employeetype mail
                    uid c postalcode cn preferredlanguage employeenumber st);

# Boiler plate to open input and output files handles.
open my $in, '<', $ldap_file or die;
open my $out, '>', $csv_file or die;

# Write the header labels.
print  $out "uid,", join (',', @header[1..$#header]), "\n";

# Work engine.
{
    # Record separator is a paragraph representation.
    local $/="\n\n";

    # Process one record at a time.
    while(my $record = <$in>) {
        chomp $record; # Remove the record separator.
        my %data;
        @data{@header} = ();  # To label the data.
        my @entries = split '\n', $record; # Create data entries.

        # Save first entry uid or it will be over written by second instance.
        $data{'uid0'} = qq{"$entries[0]"};

        # Work with each entry.
        for my $entry (@entries){
            my ($key, $value) = split "=", $entry, 2; # split only by first equal.
            $value =~ s/\s+$//; # Clean trailing spaces.
            $value = qq{"$value"} if $value =~ /,/; # Surround with double quotes any entries with comas.
            $data{$key} = $value;
        }
        # Separate entries with comas.
        my $row = join ',', (map{ $data{$_}?$data{$_}:""} @header);

        # Write to output file.
        print $out "$row\n";
    }
}
# Dismiss file handles.
close $in;
close $out;

# Feed back to user.
print "$csv_file has been saved in the current directory\n";

sub usage {
    print "Usage: $0 ldapfilename\n";
    exit 1;
}