grmshw4 has asked for the wisdom of the Perl Monks concerning the following question:

Hi, I'm very new to perl and am trying to write a script that will basically say "look in a folder and if the file that is in that folder is the same as any of the files in a second folder then rename the first file by adding an "_1". There will always only be one file in the first folder but can be many in the second folder. I wrote the code below but it doesn't seem to do anything. Help would be appreciated. Thanks! 

#! /usr/bin/perl
use diagnostics; 

$tempdir="c:/Temp/OneFile";
opendir(TMP, $tempdir) || die;
@onefile= readdir(TMP);
closedir(TMP);

$permdir="c:/Support/Files";
opendir(PMD, $permdir) || die;
@allfiles= readdir(PMD);
closedir(PMD);

our @onefile_1;

foreach $file (@allfiles)
{
 if ($file eq "@onefile")
{ 
 rename("$onefile", "@onefile_1.txt");
}
}
exit(0);

__END__
:endofperl

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Replies are listed 'Best First'.
Re: comparing folders
by toolic (Bishop) on Jul 28, 2010 at 19:03 UTC
    if ($file eq "@onefile")
    It probably doesn't work because those double quotes will interpolate all the elements of the array into a single string (with a single space between each element). Since readdir returns all of a directory's contents, @onefile probably has 3 elements: the file you expect to be there and the special dot directories (. and ..). You should filter the output with grep -f, or use nested for loops (one for each array), or load the first files into a hash.

    Inspect the contents of your array using Data::Dumper (tip #4 from the Basic debugging checklist): 

    use Data::Dumper;
print Dumper(\@onefile);

    [download]

    You should be able to adapt the solution to a similar problem: Re: Comparing Directories and copy files

    rename("$onefile", "@onefile_1.txt");
    To append _1, you really want something like this: 
    rename $onefile, $onefile . '_1.txt' or die "Can not rename: $!";

    [download]
[reply]
[d/l]
[select]
      Thanks toolic! I didn't realize that "" will interpolate the elements into a string.
[reply]
Re: comparing folders
by jwkrahn (Abbot) on Jul 28, 2010 at 20:30 UTC

    When you say "a file is the same" do you mean the file name or the file contents?

    This will compare based on the file name (UNTESTED): 

    #!/usr/bin/perl
use warnings;
use strict;


my $tempdir = 'c:/Temp/OneFile';
my $permdir = 'c:/Support/Files';

opendir my $TMP, $tempdir or die "Cannot opendir '$tempdir' $!";
my @onefile = grep -f "$tempdir/$_", readdir $TMP;
closedir $TMP;

if ( @onefile > 1 ) {
    die "Error: more than one file in $tempdir\n";
    }

if ( -f "$permdir/$onefile[0]" ) {
    rename "$tempdir/$onefile[0]", "$tempdir/$onefile[0]_1.txt" or die
+ "Cannot rename '$tempdir/$onefile[0]' to '$tempdir/$onefile[0]_1.txt
+' $!";
    }

exit 0;

__END__

    [download]
[reply]
[d/l]
      Exactly what I needed it to do, thanks jwkrahn!
[reply]
Re: comparing folders
by morgon (Priest) on Jul 28, 2010 at 19:28 UTC
    I think you want to test with "$file eq "@onefile" whether $file is contained in the array @onefile.

    This is the wrong syntax.

    What I would do is using a hash:

    my %onefile= map { $_ => 1 } readdir(TMP);
# Now every file in TMP is a key in the hash
...
# and later we check like this:
foreach $file (@allfiles)
{
 if ($onefile{$file})
...

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[reply]
[d/l]
      That's exactly what I was trying to do. Thanks for the syntax help morgon!
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