H0tc@xe has asked for the wisdom of the Perl Monks concerning the following question:

I'm trying to loop through all files in a directory, read each file into a varible (@config) and then perform regex operations and spit out the output to a file. I'm having a problem reading the files into the variable. I'm getting "Can't open 'Filename.txt': No such file or directory at ./find.pl line 14", but there are files in the directory. 

#!/usr/bin/perl -w
#

use warnings;
use strict;

opendir(DH, "Configs/");
my @files = readdir(DH);
closedir(DH);

foreach my $file (@files) {

        # Read config from .txt files in Dir.
        open my $fh, "<", $file or die "Can't open '$file': $!";
        my @config = <$fh>;
        close $fh;
        chomp @config;
 
        my $configref = \@config;
 
 
                # Extract names from config.
                my @names = map { /^name \d+\.\d+\.\d+\.\d+ ([A-Za-z0-
+9-_]+)$/ ? $1 : () } @{ $configref };
                # Remove names from config.
                @config = grep { $_ !~ /^name / } @config;
                # Find unused name references.
                foreach my $name (@names) {
                        if (!grep { $_ =~ /$name/ } @config) {
                     print "name $name unused.\n";
                }
        }       
 
 
                # Extract objects from config.
                my @objects = map { /^(object|object-group) (network|s
+ervice) ([A-Za-z0-9-_]+)$/ ? $3 : () } @{ $configref };
                # Remove objects from config.
                @config = grep { $_ !~ /^(object|object-group) / } @co
+nfig;
                # Find unused object references.
                foreach my $object (@objects) {
                        if (!grep { $_ =~ /$object/ } @config) {
                     print "object $object unused.\n";
                }       
        }

}

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Re: Trouble opening and reading file within loop (readdir)
by Anonymous Monk on Sep 21, 2015 at 22:23 UTC

    You've fallen for the basic readdir trap (you didn't RTFM close enough)

    one easy solution (read glob for caveats) my @files = glob "Configs/*";

    Path::Tiny is very convenient 

    use Path::Tiny qw/ path /;
for my $file ( path( "Configs/" )->children ){
    my @config = $file->slurp_raw;
    ...
}

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      :) s/slurp_raw/lines_raw/
[reply]
      I'm not understanding why readdir wont work in my case? The error is being thrown when the file in @files is being opened.
[reply]

        I'm not understanding why readdir wont work in my case? The error is being thrown when the file in @files is being opened.

        Why not ? use my solutions?

        Have you read readdir?

        Its a very short read (only "79" words) and it explains exactly your case

        You're not alone in this, practically 99% of all questions about readdir are this same question

        Would you like to read readdir now, or simply start using something more convenient like glob, or better yet Path::Tiny?

[reply]
Re: Trouble opening and reading file within loop
by GotToBTru (Prior) on Sep 22, 2015 at 13:05 UTC 
    /howard$: ls test
Apr15                  May15                  testpm.dat
EDI204_blah            testing_all_Oct14.tar  testpm2.pl
/howard$: perl -d -e 1
...
main::(-e:1):   1
  DB<1> $path='/howard/test/'
  DB<2> opendir(DH,$path)
  DB<3> @files=readdir(DH)
  DB<4> closedir(DH)
  DB<5> x @files
0  '.'
1  '..'
2  'Apr15'
3  'EDI204_blah'
4  'May15'
5  'testing_all_Oct14.tar'
6  'testpm.dat'
7  'testpm2.pl'
  DB<6> open $fh,'<',$files[6] or die $!
No such file or directory at (eval 22)[/home/edi/perl/5.8.8/lib/5.8.8/
+perl5db.pl:628] line 2.
  DB<7> open $fh,'<',$path . $file or die $!
  DB<8> close $fh
  DB<9> @fglob = glob($path . "*")
  DB<10> x @fglob
0  '/howard/test/Apr15'
1  '/howard/test/EDI204_blah'
2  '/howard/test/May15'
3  '/howard/test/testing_all_Oct14.tar'
4  '/howard/test/testpm.dat'
5  '/howard/test/testpm2.pl'
  DB<11> open $fh,'<',$fglob[6] or die $!
  DB<12>

    [download]

    A couple things to note:

    1. readdir returned the . and .. links, glob did not
    2. Both returned both directories and files (Apr15 and May15 are directories).
      You will want to test to make sure $file is a file before you try to open it.
    3. readdir returned file name only, glob the whole path. That's why open $fh,'<',$files[6] failed.
      I needed to append the path before opening the file.
    Dum Spiro Spero
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Re: Trouble opening and reading file within loop
by tangent (Parson) on Sep 22, 2015 at 13:00 UTC
    @files only contains the names of the files, so you need to prepend the directory path. You can change this bit: 
    open my $fh, "<", $file or die "Can't open '$file': $!";

    [download]
    to... 
    open my $fh, "<", "Configs/$file" or die "Can't open '$file': $!";

    [download]
    Update:
    In light of what GotToBTru says below, and although other ways have already been pointed out, you could add these lines: 
    foreach my $file (@files) {
    next if $file =~ m/^\./; # skip .. and .
    next unless -f "Configs/$file"; # test to see if a file
    open my $fh, "<", "Configs/$file" or die "Can't open '$file': $!";

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