selcting a specific file

[Anonymous Monk]

hi monks, i wanted to select only the each and every non empty file i had script like this

foreach $f (@files){
.....
readfile...given path
writefile.... some otherpath
}

how can i select each non empty files?? and transfer them out i follwed by !-z option but it doesnt work out

[toolic]

The -z filetest works for me on *nix:

use warnings;
use strict;
my @files = <*.txt>;
for (@files) {
    if (-z $_) {
        print "File $_ is empty\n";
    }
    else {
        print "File $_ is not empty\n";
    }
}

I have 3 files in my current directory. Only the file named "a.txt" is empty. When I run the program above, I get this output:

File a.txt is empty
File b.txt is not empty
File c.txt is not empty

[andyford]

For us to help you most effectively, you should post your actual code. We don't know what "it doesn't work out" means. Perhaps your file is not zero bytes but contains some whitespace or something?

[Anonymous Monk]

@files = grep { /\.log$/ } readdir ($DIR);
foreach my $x (@files){
open READFILE, "......";
open WRITEFILE, ">......";
while(<READFILE>){
chomp;
my @parts = split(/\s/, $_);
print WRITEFILE $parts[1], " ", $parts[0], "\n";
}
close WRITEFILE;
close READFILE;

this is the original code

[Anonymous Monk]

the file doesn't have any content

[andyford]

That's my point. -z is looking for a zero byte file, but 'no content' could be a bunch of tabs and spaces.

[forda@hqnagtl1 ~]$ touch emptytest1
[forda@hqnagtl1 ~]$ touch emptytest2
[forda@hqnagtl1 ~]$ ls -l emptytest*
-rw-rw-r--  1 forda forda 0 Oct 22 17:19 emptytest1
-rw-rw-r--  1 forda forda 0 Oct 22 17:19 emptytest2
[forda@hqnagtl1 ~]$ echo '              ' >> emptytest2
[forda@hqnagtl1 ~]$ ls -l emptytest*
-rw-rw-r--  1 forda forda  0 Oct 22 17:19 emptytest1
-rw-rw-r--  1 forda forda 15 Oct 22 17:20 emptytest2

I put some spaces into a formerly empty file and now it has a size of 15.

[swampyankee]

My experience is that all the -X file operators work on Windows and FreeBSD. You could try

@files = grep { -s and -f} @files;

I would make sure that it's actually a file; directories on *ix-ish systems have non-zero size. It would probably also make sense to check to see if you have the required permissions for copying the file into another location, e.g. on *ix, you need write access in the target directory.

Copying files can be done with File::Copy or system,

---

...kudos to blazar for his observation about _ and the -X operators.

[blazar]

@files = grep { -s and -f} @files;

I personally believe that this is fine, but to avoid a double stat one would better

@files = grep { -s and -f _} @files;

Of course it would be nice to also have chained -X's, and IIRC 5.10 has them.

[mwah]

how can i select each non empty files?? and transfer them out i follwed by !-z option but it doesnt work out

Your question is hard to follow but I'll try on it.

From guessing on your riddle, I'd think you should use the File:Copy module like here:

use strict;
use warnings;
use File::Copy;

my @files = qw(Ardbeg.txt Bowmore.txt Bruichladdich.txt Bunnahabhain.t
+xt
               Caol_Ila.txt Kilchoman.txt Lagavulin.txt Laphroaig.txt
               Port_Charlotte.txt);

my $given_path = '/tmp/allfiles';
my $some_otherpath = '/tmp/nonemptyfiles';

for my $f (@files) {
   if( -f "$given_path/$f" && ! -z "$given_path/$f" ) {
      copy( "$given_path/$f", "$some_otherpath/$f" )
   }
}

BTW: you should watch out for the path separators on your system. On Mac, its the : (column) and not the / (slash) as in Unix/Linux and probably Win32 (maybe you need even the \\ (backslash) for the latter, but I can't really believe this ;-).

Regards

mwa

[moritz]

my @nonempty_files = grep { ! -z $_ } @files;

[mwah]

this:

 my @nonempty_files = grep { ! -z $_ } @files;

looks not very trustworthy ;-). This might be wrong. Compare some test schenarios with this approach:

 ...
 my @nonempty_files = grep -e && !-z, @files;
 ...

(especially for non-accessible and non-existent files.)

Regards

mwa

[Anonymous Monk]

@files = grep { /\.c$/ } readdir ($DIR);

opening a dir a selcting .c files !! how to use this !-z!!!

[Anonymous Monk]

this is the original code

@files = grep { /\.log$/ } readdir ($DIR);
foreach my $x (@files){
open READFILE, "......";
open WRITEFILE, ">......";
while(<READFILE>){
chomp;
my @parts = split(/\s/, $_);
print WRITEFILE $parts[1], " ", $parts[0], "\n";
}
close WRITEFILE;
close READFILE;

[mwah]

Your code won't compile. That's not very dire. Just stay comitted to it ;-)

use strict;
use warnings;

my $path = '/tmp/allfiles';
my $outpath = '/tmp/nonemptyfiles';
opendir my $dh, $path or die $!;
my @files = grep /\.log$/ && -f "$path/$_" && !-z "$path/$_", readdir 
+$dh;
closedir $dh;

for my $fn (@files){
   open my $fr, '<', "$path/$fn" or die "IN: $fn $!";
   open my $fw, '>', "$outpath/$fn" or die "OUT: $fn $!";;
   while( <$fr> ) {
      printf $fw "$1 $2\n" if /(\S+)\s+(\S+)/
   }
}

Try to study the example and bear some idomatic expressions in mind like indirect file handles and checks for success ...

Regards

mwa