trying to rename files

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

I am new Perl and programming and saw a snippet on here I thought I would try to fix to work for me, but its not working. What am I doing wrong? Any help would be greatly appreciated. For testing I wanted to change all files named "append" to "aPPend"

die("Cannot open /cdw/home_dir/s006258/MarketingDB/.")
    unless(opendir(DIR, "/cdw/home_dir/s006258/MarketingDB/"));
    
#Print to new file 
die("Cannot open Log file to read from.")
    unless(open(FILES, ">List_of_files_changed.txt"));

    print "Reading from file\n";    
    #reading from file 
for my $file (readdir(DIR)) {
        if($file =~ /^append/) {
        print "$file\n";
        $old=$_;
        s/^append/aPPend/;
        die "$_ already exists" if (-e $_);
        print "$old is old and $_ is new\n";
        rename($old, $_) or die "Failed to rename\n";
    }
}
[download]

The output for the last print statemen gives me " is old and new is new" and says "Failed to rename". Thanks again...

Comment on trying to rename files Download Code

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Re: trying to rename files by ikegami (Patriarch) on Jun 09, 2006 at 20:25 UTC
You keep using `$_`, but the file name is in `$file`. `readdir` returns file names, not paths. You'll need to prepend the file names you pass to `-e` and `rename` with `/cdw/home_dir/s006258/MarketingDB/`. Why do you hide your actions after your error messages? Instead of `die(...) unless (`action`)` use action `or die(...)` You never write to your log. `foreach my $file (readdir(DIR))` loads the entire list into memory, whereas `while (defined(my $file = readdir(DIR)))` reads one at a time. You're very random in your use of parenthesises. Be consistent. Cleaned up code: #!/usr/bin/perl use strict; use warnings; use File::Spec (); my $dir = '/cdw/home_dir/s006258/MarketingDB'; my $log = 'List_of_files_changed.txt'; opendir(local DIR, $dir) or die("Cannot open $dir.\n"); open(local FILES, '>', $log) or die("Cannot open output file $log.\n"); while (defined(my $file = $filereaddir(DIR))) { next unless $file =~ /^append/; my $old = my $new = $file; $new =~ s/^append/aPPend/; $old = File::Spec->catfile($dir, $old); $new = File::Spec->catfile($dir, $new); die("Unable to rename $old: $new already exists.\n") if -e $new; rename($old, $new) or die("Unable to rename $old: $!\n"); print FILES ("$old renamed to $new\n"); } [download] Updated. Update: 3rd point was backwards.	[reply] [d/l] [select]
Re^2: trying to rename files by Anonymous Monk on Jun 09, 2006 at 20:29 UTC
I did that and still gives me the same output.... Is the "s/^append/aPPend/;" even relevant? How does it know what file to do a substitution against?	[reply]
Re: trying to rename files by philcrow (Priest) on Jun 09, 2006 at 20:40 UTC
Maybe I'm missing something, but I can't see where $_ gets set to anything useful (which is probably a good thing overall). Where you have $_ I think you need to have $file instead, since you have named it in the for declaration. Then also change the s/// to operate on $file: `$file =~ s/^append/aPPend/;` [download] If you omit the left hand side, the s/// will apply to $_, but as I mentioned, I don't think that's being set. Phil	[reply] [d/l]
Re^2: trying to rename files by Anonymous Monk on Jun 09, 2006 at 21:15 UTC
Thanks everyone it works perfectly...... Great to have such good resources like u guys on here... Great site...	[reply]
Re: trying to rename files by gellyfish (Monsignor) on Jun 09, 2006 at 20:39 UTC
You don't get the full path of the file from `readdir` - you need to append the path to the filename before you do the rename. I'm also not sure what you think you are doing with the `$_` - if you supplied `use warnings` you would be told about the problem. /J\	[reply] [d/l] [select]
Re: trying to rename files by bigmacbear (Monk) on Jun 09, 2006 at 20:45 UTC
Looks like you're missing a couple of things here. You open a file for writing (`">List_of_files_changed.txt"`) and then never use the associated file handle. Perhaps you intended to redirect one of your print statements using `print FILES ...`, but didn't. Within a for loop, if you specify a variable to be filled (as you do by specifying `for my $file`), `$_` doesn't get filled in. Either use `$file` or `$_`, not both. Hope this helps.	[reply]