Perl is quite close to ideal for this sort of work.

My first tendency would be to use split; this means I get avoid playing games with substr (If I had to do that, I don't see much point is using Perl 8-)).

substr will work. The only issue, then, is how to determine which start/length pair to use for each file. This is easy (pseudo-code, not real code follows!):

my %layout = (file1 => 0, file2 => 0, ... file8 => 20,
              file9 ->10, file10 => 11);

#note that Perl starts counting at zero, so 1 had to be subtracted fro
+m the starting positions.

# now, for each file, you could yank the acct number out like this:

$acct = substr($line, $layout{$file_name}, 9);

# where $file_name corresponds to file1, file2, etc, in %layout as app
+ropriat
[download]

Now, if your file names are not fixed, but use a predictable naming convention, the problem is slightly different, but still easy. Magic cookies would be similarly simple. If the files have column headers, you could parse that to find which field has account numbers. This is slightly trickier.

So, you code would have this sort of logic:

• Read list of account numbers. It's small, so store it in an array (open(my $acct, "<",$account_to_check);@acct_num = <$acct>;)
• Open one info file (there are ten...). Use the %layout hash to find where the account number starts.
• Using substr and the %layout table, yank out the account number. If it's on your list (grep is perfect for this), perform your extract, and either print or store the information. If it's not, use next to skip to the next record.
• Repeat as needed

Again, my preference is generally to use split for simple delimited files; if you've got fields which include the pipe symbol (A|B|C|"this has a | pipe symbol but is one field"), you'll be better served by using a module, such as Text::CSV (I'm not endorsing that one; the only delimited files I've dealt with, I've controlled, so I knew, with certainty, that I wouldn't have fields where the delimiter should be ignored).

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