Perl program help on opendir and readdir

Question

So I have a program that I want to clean some text files. The program asks for the user to enter the full pathway of a directory containing these text files. From there I want to read the files in the directory, print them to a new file (that is specified by the user), and then clean them in the way I need. I have already written the script to clean the text files.

I ask the user for the directory to use:

chomp ($user_supplied_directory = <STDIN>); 
opendir (DIR, $user_supplied_directory);

Then I need to read the directory.

my @dir = readdir DIR;

foreach (@dir) {

Now I am lost.

Any help please?

Answer 1

I'm not certain of what do you want. So, I made some assumptions:

• When you say clean the text file, you meant delete the text file
• The names of the files you want to write into are formed by a pattern.

So, if I'm right, try something like this:

chomp ($user_supplied_directory = <STDIN>);

opendir (DIR, $user_supplied_directory);
my @dir = readdir DIR;

foreach (@dir) {
    next if (($_ eq '.') || ($_ eq '..'));

    # Reads the content of the original file
    open FILE, $_;
    $contents = <FILE>;
    close FILE;

    # Here you supply the new filename
    $new_filename = $_ . ".new";

    # Writes the content to the new file
    open FILE, '>'.$new_filename;
    print FILE $content;
    close FILE;

    # Deletes the old file
    unlink $_;
}

Answer 2

I would suggest that you switch to File::Find. It can be a bit of a challenge in the beginning but it is powerful and cross-platform.

But, to answer your question, try something like:

my @files = readdir DIR;
foreach $file (@files) {
   foo($user_supplied_directory/$file);
}

where "foo" is whatever you need to do to the files. A few notes might help:

• using "@dir" as the array of files was a bit misleading
• the folder name needs to be prepended to the file name to get the right file
• it might be convenient to use grep to throw out unwanted files and subfolders, especially ".."

Answer 3

I wrote something today that used readdir. Maybe you can learn something from it. This is just a part of a (somewhat) larger program:

our @Perls = ();

{
    my $perl_rx = qr { ^ perl [\d.] + $ }x;
    for my $dir (split(/:/, $ENV{PATH})) {
        ### scanning: $dir
        my $relative = ($dir =~ m{^/});
        my $dirpath = $relative ? $dir : "$cwd/$dir";
        unless (chdir($dirpath)) {
            warn "can't cd to $dirpath: $!\n";
            next;
        }
        opendir(my $dot, ".") || next;
        while ($_ = readdir($dot)) {
            next unless /$perl_rx/o;
            ### considering: $_
            next unless -f;
            next unless -x _;
            ### saving: $_
            push @Perls, "$dir/$_";
        }
    }
}

{
    my $two_dots = qr{ [.] .* [.] }x;
    if (grep /$two_dots/, @Perls) {
        @Perls = grep /$two_dots/, @Perls;
    }
}

{
    my (%seen, $dev, $ino);
    @Perls = grep {
        ($dev, $ino) = stat $_;
        ! $seen{$dev, $ino}++;
    } @Perls;
}

The crux is push(@Perls, "$dir/$_"): filenames read by readdir are basenames only; they are not full pathnames.

Answer 4

You can do the following, which allows the user to supply their own directory or, if no directory is specified by the user, it defaults to a designated location.

The example shows the use of opendir, readdir, stores all files in the directory in the @files array, and only files that end with '.txt' in the @keys array. The while loop ensures that the full path to the files are stored in the arrays.

This assumes that your "text files" end with the ".txt" suffix. I hope that helps, as I'm not quite sure what's meant by "cleaning the files".

use feature ':5.24';
use File::Copy;

my $dir = shift || "/some/default/directory";

opendir(my $dh, $dir) || die "Can't open $dir: $!";

while ( readdir $dh ) {
    push( @files, "$dir/$_");
}

# store ".txt" files in new array
foreach $file ( @files ) {
    push( @keys, $file ) if $file =~ /(\S+\.txt\z)/g;
}

# Move files to new location, even if it's across different devices
for ( @keys ) {
    move $_, "/some/other/directory/"; || die "Couldn't move files: $!\n";
}

See the perldoc of File::Copy for more info.