Humbled, I return for wisdom. The while statements are erratic, my wish is to have a 1to1 relationship between the while statements and the input files, yet the 2nd while <MGR> will pull results for 50 lines before the first while <PERSON> runs again. I wish to read iteratively <PERSON> one line at a time, then print @lines, then read iteratively <MGR>, one line at a time, resulting in a four lines written to OUT or buildAD.ldif.

Also, perl throws an error on the second $_ use; how else may it be defined as I wish to place the next line from <MGR> file into the filter?

Error reads: Use of uninitialized value $_ in pattern match (m//) at build4.pl line 48, <MGR> line 120 (#1)(W uninitialized) An undefined value was used as if it were already defined. It was interpreted as a "" or a 0, but maybe it was a mistake. To suppress this warning assign a defined value to your variables.

I am also puzzled why print OUT (@lines) does not print the contents of LDIFA after each line of <PERSON> is processed (instead it is printing erratically to OUT). And, why OUT fails in Net::LDAP::LDIF->new( "OUT", "a", wrap=>40 );, I am forced to hardcode "buildAD.ldif" instead of OUT.

my $ldap = Net::LDAP->new("$HOST", port=>389) or die "$@";
my $dn = $ldap->bind("$ADMIN", password=>"$PWD");
my $dnm = $ldap->bind("$ADMIN", password=>"$PWD");
my @attr = "1.1";
my $result = Net::LDAP::LDIF->new( "buildAD.ldif", "a", wrap=>40 );
my @lines = (<LDIFA>);

while (<PERSON>)
{
chomp;
$dn = $ldap->search( #return only the employeeID DN
        base => "$BASEDN",
        filter => "(&(objectClass=user)(employeeID=$_))",
        scope => "sub",
        attrs => [@attr]
        );

        next unless $dn; # Make sure something is returned
while( my $entry = $dn->pop_entry() )
{
        $result->write_entry($entry);
        if ( $result != /dn:/ )
{
        print OUT (@lines);
}
while (<MGR>)
{
chomp;
$dnm = $ldap->search( #return only the manager DN
        base => "$BASEDN",
        filter => "(&(objectClass=user)(employeeID=$_))",
        scope => "sub",
        attrs => [@attr]
        );

        next unless $dnm; # Make sure something is returned
while( my $entry = $dnm->pop_entry() )
{
        $result->write_entry($entry);
}
}
}
}

$dn = $ldap->unbind;  #session ends
$dnm = $ldap->unbind;  #session ends

close OUT2 or die "Cannot close in-memory file: $!";
close OUT or die "Cannot close in-memory file: $!";
close MGR or die "Cannot close in-memory file: $!";
close PERSON or die "Cannot close in-memory file: $!";
close LDIFA or die "Cannot close in-memory file: $!";
[download]

If you find yourself having problems with nested loops, it helps to indent your code so the structure becomes clearer:

while (<PERSON>)
{
chomp;
$dn = $ldap->search( #return only the employeeID DN
        base => "$BASEDN",
        filter => "(&(objectClass=user)(employeeID=$_))",
        scope => "sub",
        attrs => [@attr]
        );

        next unless $dn; # Make sure something is returned
while( my $entry = $dn->pop_entry() )
{
        $result->write_entry($entry);
        if ( $result != /dn:/ )
{
        print OUT (@lines);
}
while (<MGR>)
{
...
[download]

could be reindented as

while (<PERSON>)
{
    chomp;
    $dn = $ldap->search( #return only the employeeID DN
        base => "$BASEDN",
        filter => "(&(objectClass=user)(employeeID=$_))",
        scope => "sub",
        attrs => [@attr]
        );

        next unless $dn; # Make sure something is returned
    while( my $entry = $dn->pop_entry() )
    {
        $result->write_entry($entry);
        if ( $result != /dn:/ )
    {
        print OUT (@lines);
    }
    while (<MGR>)
    {
    ...
[download]

So, you'll see that once you've read to the end of MGR, you'll still have lines in PERSON. Maybe you want to look up data from the contents of MGR? Then a hash is a better structure:

my %manager;
while (<MGR>) {
    $manager{ $_ } = $ldap->search(...); # return only the manager DN
};

while (<PERSON>) {
    ... # you never seem to use the information from MGR here...
};
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In addition to Corion's wise words,

Your code:

 if ( $result != /dn:/ )
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probably does not do what you think it does - and I'm curious to know what you think it does.
That is probably why you are puzzled about the contents out OUT.

You probably want to see if $entry contains "dn" and negate that:

if ( $entry !~ /dn:/ )
[download]

     Syntactic sugar causes cancer of the semicolon.        --Alan Perlis

Temporarily, I am working on different code to achieve the same result. So I may better understand Perl, I submit the following code, albeit not working. I gratefully await your expertise on why it does not work. Grateful for your expertise. This code erractically outputs to OUT. Where should chomp; go in this example? Both PERSON and MGR have an equal number of lines. The desired result is:

line1 from PERSON 
changetype: modify 
replace: manager 
line1 from MGR 

line2 from PERSON 
changetype: modify 
replace: manager 
line2 from MGR 

...etc... 

#! perl -slw 
use strict; 
use warnings; 
use diagnostics; 
use constant batchdir => "c:\temp10"; 

open (PERSON,"f1"); 
open (MGR,"f2"); 
open OUT, ">", "buildAD.ldif" or die "Cannot write to 'buildAD.ldif': 
+$!"; 
truncate (OUT, 0); 

my $line; 
my $line2; 

while ($line = <PERSON>) { 
#chomp; 
my @dn1 = split(/\s+/,$line); 
my $count = scalar(@dn1); 
print OUT "$line"; 
print OUT "changetype: modify"; 
print OUT "replace: manager"; 

while ($line2 = <MGR>) { 
#chomp; 
my @dn2 = split(/\s+/,$line2); 
my $count2 = scalar(@dn2); 
print OUT $line2, "\n", if ($count == $count2); 
} 
} 

close PERSON; 
close MGR; 
close OUT; 
exit;
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Example data in OUT is here, the extra newline on line 2 should not be there, and all the numbers after 2821 are from <MGR>.

0104 

changetype: modify 
replace: manager 
2821 


3682 


1129 


2050 


4054 


0755
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Much closer, I've written the following code, albeit also not working, with the same intent. The issue here is that, see OUT example below, only the first line of <PERSON> is read; instead of line1 from <PERSON>, then line1 from <MGR>, then line2 from <PERSON>, then line2 <MGR>, etc.

while (<PERSON>) {
        chomp;
        my $input1 = $_;
                while (<MGR>) {
                chomp;
                my $input2 = $_;
                        print OUT $input1;
                        print OUT "changetype: modify";
                        print OUT "replace: manager";
                        print OUT $input2, "\n";
                        }
}

exit;
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Output from OUT

0479
changetype: modify
replace: manager
4410

0479
changetype: modify
replace: manager
8050

0479
changetype: modify
replace: manager
0650

0479
changetype: modify
replace: manager
7030

0479
changetype: modify
replace: manager
9857

0479
changetype: modify
replace: manager
4380
[download]