Re^2: removing the need for tmp files from script

Fantastic information. I was wondering though, you don't seem to be able to use the "filehandle" variable like a real file in a script. For example: I have this beginnerish script

open my $fh2, '<', '/tmp/mlist.txt' or die "unable to open file '$file
+' for reading : $!";
open my $fh9, '>', '/tmp/listk.txt' or die "unable to open file '$file
+' for reading : $!";
while (<$fh2>) {
   my @fields = split(',', $_);
 local $" = ',';
       if ($fields[2] eq '1' || $fields[2] eq '0') {
             print $fh9 "@fields[4]\n" if /MONTHLY/ && !/,-,/;
             }
           }
           close $fh2;
           close $fh9;
[download]

This is clumsy but it works. However, if I try to use the variable assigned to a filehandle in the same way:

open my $bpfh1, '<', \$forbpjoutput or die $!;
  while (<$bpfh1>) {
my @fields = split(',', $_);
my $fields;
 local $" = ',';

       if ($fields[2] eq '1' ||$fields[2] eq '0') {
             print "THESE ARE THE>>> $fields[4]\n" if /MONTHLY/ && !/,
+-,/;
        
close $bpfh1;
             }
          }
[download]

it does work but what happens is that it never stops printing the "file" or the fields4 It continues until out of memory. Is there a way to do this differently? This is probably a very basic question, but I don't have much experience with filehandles which are variables.

Comment on Re^2: removing the need for tmp files from script Select or Download Code

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Re^3: removing the need for tmp files from script by Cristoforo (Curate) on Jul 25, 2016 at 22:53 UTC
Hi novice2015 The link to open that BillKSmith mentioned in his post has the following text. `# in-memory files 21. open(my $memory, ">", \$var) 22. or die "Can't open memory file: $!"; 23. print $memory "foo!\n"; # output will appear in $var` [download] This shows how to write to an in-memory file. To read from an in memory file, you would do this: `#!/usr/bin/perl use strict; use warnings; my $file = 'here are some words I want '; open my $fh, '<', \$file; chomp(my @words = <$fh>); my $pattern = join "\|", @words; print $pattern;` [download] That would be a way to not need the tmp. file.	[reply] [d/l] [select]
Re^4: removing the need for tmp files from script by novice2015 (Acolyte) on Jul 29, 2016 at 21:15 UTC
this works great. However, I have one issue in that the file has 2 lines in it and only the first line gets printed. `my $pattern = join '\|', @words; my $forx; open my $bpfh1, '>', \$forx or die $!; for (@bpj) { print $bpfh1 "$_\n", $_ if /$pattern/; } open my $bpfh1, '<', \$forx or die $!; while (<$bpfh1>) { my @fields = split(',', $_); my $fields; local $" = ','; if ($fields[2] eq '1' \|\|$fields[2] eq '0') { print "THESE ARE THE>>$fields[4]\n" if /MONTHLY/ && !/,-, +/; } close $bpfh1; } close $bpfh1; }` [download] So what I get is LISTING-INVENTORY-CATALOG LISTING-PURCHASING-CATALOG The variable (memory file) $forx does contain data, and it prints out just fine. But only the first line. I have tried different things to make the second line print, such as closing the file earlier, but it doesn't work. I've had this problem before but can't remember how I got it resolved. Any ideas?	[reply] [d/l]
Re^3: removing the need for tmp files from script by BillKSmith (Monsignor) on Jul 26, 2016 at 12:19 UTC
I cannot duplicate your problem. When I run your code on my system (perl v5.20.2 on Windows 10), it terminates with no error messages and no output. It I use warnings, I get several copies of a warning about uninitialized value in $bpfh1. If I declare $forbpjoutput as a lexical variable and define it as a null string, I get no messages and no output even using strict and warnings. (This is exactly what I expect). `use strict; use warnings; my $forbpjoutput = q(); open my $bpfh1, '<', \$forbpjoutput or die $!; ... # Exactly as in your post.` [download] As Cristoforo pointed out, you probably did not intend to input from a null file. I cannot guess what you really did intend to do. Bill	[reply] [d/l]