I'm returning it in a function call...

In case the string is huge and you want to avoid some temporary memory allocation (which could push up the peak memory usage of the program), you could return a reference to the scalar:

#!/usr/bin/perl

sub mem {
    print "$_[0]:\n";
    system "/bin/ps", "-osize,vsize", $$;
}

sub foo {
    mem(0);
    my $data;
    $data .= "xxxxxxxxxx" for 1..1_000_000;
    mem(1);
    return \$data;  # return reference
}

my $r = foo();  # then get at the data using $$r
mem(2);

__END__
$ ./880173.pl
0:
   SZ    VSZ
  612  19804
1:
   SZ    VSZ
10468  29660
2:
   SZ    VSZ
10468  29660
[download]

Using the same snippet, but with return $data, you'd get:

0:
   SZ    VSZ
  612  19804
1:
   SZ    VSZ
10468  29660
2:
   SZ    VSZ
20236  39428
[download]

As you can see, the process size has grown additionally by about the size of $data.

Whether this really saves anything overall depends on what else the program is doing to actually print the string, etc.

Ok, ill try that! But, what is the most efficient way to open the file?

Really, does it matter? It's like asking the most efficient way to close your car door to minimize the time of your Miami to New York road trip.

As the Anonymous Monk already said, you can use open or sysopen, but there probably won't be much difference, as most likely the majority of the time is spent in the underlying system call open(2), i.e. outside of the Perl program/in the kernel.

If you really want to know: Benchmark.

I'm not sure if I understand you fully. You want to send a file to a printer and use Perl for that?

I don't get why you want to put the data into a scalar in the first place? Why not send the file to the printer immediately? There several modules on CPAN to work with printers. Maybe Net::Printer? You didn't mention the platform you're on nor how your printing is setup. Maybe you should elaborate a bit.

Cheers

Harry

Seeing how there are only 2 pure-perl ways to do it, its either open/read, or sysopen/sysread -- sysopen might be faster (probably); I doubt it matters