Read .txt file -> append extension -> find on disc -> delete

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

Hello Monks!

Task: I have a .txt file with filenames which have to be deleted. I need to read the file, append the ".png" and ".txt" extension to the filenames. Then, I need to search for those files on my system, print out the full paths and in the end, to delete the files. This is what I got until now:

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

use File::Find;

print "Files to be deleted: \n";
open ("file", "remove.txt") || die ("Could not open file. \n $!");

@text=<file>;
print(@text);
close("file");


my $dir = "/Downloads/png_files/";
find(\&wanted, $dir);

sub wanted {
    print $File::Find::name if -d
};
[download]

Problem: I tried, but failed, in appending the extensions to the filenames in my .txt file and I also do not know how to pass the values stored in the array to the find () subroutine, the "if" clause.

I just started learning Perl and it's a bit out of my reach. If anyone can lend a helping hand, I would appreciate it.

Thank you!

Comment on Read .txt file -> append extension -> find on disc -> delete Download Code

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Re: Read .txt file -> append extension -> find on disc -> delete by Perlbotics (Archbishop) on Oct 27, 2012 at 12:35 UTC
Hi forro and welcome to the Monastery. Here are some hints to get you going: First correct the errors `use strict;` is giving you. Hint: my. Do not forget to chomp( @text ); otherwise you could end up searching for somefileame\n.png which most likely does not exist. Put the filenames from `@text` into a hash `%files_to_find` for easy lookup by using a for-loop or map. Decide if you want to create hash-entries for the filename only or for the two variations (filename.txt, filename.png). Creating hash-entries for both names (as keys) makes the wanted()-sub less complex but uses more memory. However, memory-consumption is most likely not an issue here unless you have several hundreds of million files in your remove.txt. In the wanted()-sub, check if `$files_to_find{$filename}` exists. Whether `$filename` is `$_` (the filename w/o directory) or `$File::Find::name` depends on the format of the entries in remove.txt - i.e. if the entries are basenames or also include the full path. You should also check if the file in question is a regular file (-f). If a match has been found, put the abs. filename in a `@remove_these_files` list for review and removal in a later step. Remove files from `@remove_these_files` after the FF-search. Make a backup and just print out what would have been removed before fiddling around with unlink. Minor nitpick: The open() doesn't look right. Try `open( my $file, '<', "remove.txt") or ....`. Then read from `<$file>`. What you do works, but you create a file-handle `file` that's visible throughout your program. Usually not a good idea, but IMO tolerable for a small script. It might just be a good idea to get into the 3-args-open-habit early.	[reply] [d/l] [select]
Re: Read .txt file -> append extension -> find on disc -> delete by Anonymous Monk on Oct 27, 2012 at 10:15 UTC
I just started learning Perl and it's a bit out of my reach. If anyone can lend a helping hand, I would appreciate it. perlintro gives a quick leg-up, as does http://perl-tutorial.org/	[reply]
Re: Read .txt file -> append extension -> find on disc -> delete by Anonymous Monk on Oct 27, 2012 at 10:25 UTC
Problem: I tried, but failed, in appending the extensions to the filenames in my .txt file You should show that too :) and I also do not know how to pass the values stored in the array to the find () subroutine, the "if" clause. File::Find#SYNOPSIS gives examples	[reply]