Check for an empty file

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

Hi! I'm using some software within my perl script and need to identify whether in the input file is empty or not before the processing starts. What I've written below isn't working. Is there an easier way to do this than calling the system? I tried opening the file and looking at the first line, but the while loop interferes with my logic.

 #!/usr/bin/perl5.8.8

use strict;
use warnings;
    my $cmd = "-s /home/vcg/Documents/Trial/temp";
     if    (system($cmd) == 0)
    {
    print "File exists!";
    }
    else { print "File does NOT exist!";}
[download]

Forever Thanks!

Comment on Check for an empty file Download Code

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Re: Check for an empty file by ikegami (Patriarch) on Sep 22, 2011 at 18:56 UTC
You could use Perl's `-s` instead of the shell's. `if (-s "/home/vcg/Documents/Trial/temp")` [download] Note that empty (-z or !-s) and non-existent (!-e) are different things.	[reply] [d/l] [select]
Re^2: Check for an empty file by Jeri (Scribe) on Sep 22, 2011 at 19:04 UTC
Thanks! It's working great! I'd prefer not to use the shell if I can help it!	[reply]
Re^2: Check for an empty file by ChuckularOne (Prior) on Sep 23, 2011 at 12:36 UTC
I had some trouble with this a while back. -s returns a zero if the file is either zero bytes or nonexistent. It got a bit confusing until I worked out what was happening.	[reply]
Re^3: Check for an empty file by ikegami (Patriarch) on Sep 23, 2011 at 16:35 UTC
Actually, it returns undef (and sets $!) if the file is non-existent.	[reply]
Re: Check for an empty file by roboticus (Chancellor) on Sep 22, 2011 at 18:55 UTC
Jeri: `if ( -z '/home/vcg/Documents/Trial/temp' ) { print "File is empty!\n"; }` [download] See perlfunc for the other -X file/dir checking functions. ...roboticus When your only tool is a hammer, all problems look like your thumb. Update: Added link to perlfunc.	[reply] [d/l]