#! / usr/bin/perl -w

use strict;
use warnings;

use POSIX 'strftime';

my $nm = strftime('%Y', localtime).".txt";

my $filename = 'Facs_Data.txt';
open my $fh, '<', $filename
    or die "Couldn't open '$filename': $!";

my @lines = map  { /:([^\s]+)/ ? $1 : () } # take the stuff between th
+e : and the first blank
            grep { /Acct:/ } <$fh>; # Read a file line by line and sel
+ect the lines matching Acct:
        my $outfile = $_."_"."$nm" for @lines ;
        print $outfile;
        #open (OUTFILE, ">$outfile");
# do whatever with the values in @lines
#print "$_\n" for @lines;
close($filename);
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root@localhost:~/GoldenLFiles# perl facs.pl Use of uninitialized value $outfile in print at facs.pl line 17, <$fh> line 168801.

        my $outfile = $_."_"."$nm" for @lines ;
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This line will set/declare $outfile in a loop, which is unlikely to be what you want.

Did you want a loop over @lines instead? Or did you want to take the first element of @lines?

print sprintf "Have %d items\n", 0+@lines;

my $item = $lines[0];
my $outfile = $item . '_' . $nm;
print "$outfile\n";
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I tried the following code with the input data in the __DATA__ section for convenience:

#! / usr/bin/perl -w

use strict;
use warnings;

use POSIX 'strftime';

my $nm = strftime('%Y', localtime).".txt";

my @lines = map  { /:([^\s]+)/ ? $1 : () } # take the stuff between th
+e : and the first blank
            grep { /Acct:/ }
            <DATA>; # Read a file line by line and select the lines ma
+tching Acct:

print sprintf "Have %d items\n", 0+@lines;

my $item = $lines[0];
my $outfile = $item . '_' . $nm;
print "$outfile\n";

print $outfile;
#open (OUTFILE, ">$outfile");
# do whatever with the values in @lines
#print "$_\n" for @lines;

__DATA__

foo

Acct:123
Acct:456

bar
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Note that you have a close($filename), which likely should be close($fh) in your code.

Thanks You Corion, Yes, I think I want to loop over @lines. The $outfile I am trying to create here is a separate file for each Account designated by Acct:1234 (the 1234 actually).

To explain a bit there are SEVERAL lines of text following this line (including this line) that need to be written to that file name.

I wish this to happen for each section where the Acct:#### occurs, but first I wanted to learn how to create the file in the form of 1234_2017.txt.

Does this make sense ?