qx//

Of course, you could just do it in Perl.

sub line_count {
   my ($fname) = @_;
   open(my $fh, '<', $fname)
      or die("Unable to open file \"$fname\": $!\n");
   1 while <$fh>;
   return $.;
}
[download]

Thanks. But actually I want to find the total number of lines without opening the file. Also, i am keen to learn how can we use the output of system command (that is directed to STDOUT) within our program.
Gaurav
"Wisdom begins in wonder" - Socrates, philosopher

But actually I want to find the total number of lines without opening the file

Impossible. Actually, using system or backticks, you are creating a new process and opening more files than you would just using Perl.

Update: But if you insist on forking, how about

sub line_count {
   my ($fname) = @_;
   open(my $pipe, '-|', 'cat', $fname)
      or die("Unable to launch cat: $!\n");
   1 while <$pipe>;
   return $.;
}
[download]

I want to find the total number of lines without opening the file

There's simply no way to do that.

If you use wc -l, it opens the file, reads through the content (counting newlines), closes the file and returns a count. Whether you do the reading in Perl, or some external program does, it still must occur.

Also, i am keen to learn how can we use the output of system command (that is directed to STDOUT) within our program

Use backticks:

  my $file = '/path/to/file';
  my $output = `/bin/wc -l '$file'`;
[download]

Note $file is subject to shell-escaping rules.

Alternatively, you can use the pipe form of open as ikegami has already observed.

-David

my $result = `wc -l some_file`;
[download]

There is more than one way ...
:)


open( FH, "file_name" ) or die $!;
@lines = <FH>;
$num_of_lines = @lines;
print "NUm of lines : $num_of_lines\n";
[download]


YOu may do it this way tooo...