Re: New to Perl: Finding files on FTP

You don't even need to change the directory. Give this a shot -- it stores the contents of a directory and removes non-files

my $dir = '/genomes/Bacteria';
  # use single quotes where possible, e.g., no var or \n
  # it's a tiny bit faster

## get the contents of a directory
my @dir_listing = <$dir/*>;
  ## note: using <$dir/*/> would find all the directories

## removes . and ..
while ($dir_listing[0] =~ /^\.+$/)
{
  shift @{$dir_listing};
}

## removes all directories
my @files_found = map { (-d $_) ? () : $_ } @dir_listing;
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Re^2: New to Perl: Finding files on FTP by Klaas (Initiate) on Mar 14, 2012 at 18:03 UTC
Thanks! You are right, I don't need to change the directory. Let me experiment with your code a bit, need to understand the map function and get a better grasp of the `while ($dir_listing[0] =~ /^\.+$/) { shift @{$dir_listing}; }` [download] I guess I would do this with a for loop, so I can just shift $dir_listing at position i. And I need to search all the subdirs as well, but I think I'll find a way. Thanks again!	[reply] [d/l]
Re^3: New to Perl: Finding files on FTP by runrig (Abbot) on Mar 14, 2012 at 20:29 UTC
If you can't change to the directory, you probably can't list the directory or get files from the directory either. Add `$ftp->message()` to all the "or die" messages after the connect to get the reason for failure (on connect, $@ gives the reason). E.g.: `... or die "cannot list any DIRs " . $ftp->message();` [download]	[reply] [d/l] [select]
Re^4: New to Perl: Finding files on FTP by Klaas (Initiate) on Mar 15, 2012 at 10:58 UTC
Thanks, will do!	[reply]
Re^3: New to Perl: Finding files on FTP by muppetjones (Novice) on Mar 14, 2012 at 21:00 UTC
So...I made a mistake. I generally prefer to use array and reference hashes, so `shift @{$dir_listing}` was out of habit. However, the code I gave actually declared an array so, `shift @dir_listing;`is the correct way to do it. Regarding your comments, the while loop looks at the first element in the array and checks to see if it is just a series of dots using a regex, i.e., either '.' or '..'. If so, it removes the first element and checks again. For map, you can think of it as a very specialized foreach loop (`map { <expr> } <array>`) that returns values depending on the code used in the brackets. However, it is a little slower than a foreach loop so you generally only want to use it when you're using its output. It's a great way to modify or filter out values from an array.	[reply] [d/l] [select]