open the file for simple output (not for append, just plain old simple output). If the file open is successful, the file will be truncated, as per the POD: open.

{    
    open my $wipe_file, '>', $filename or die $!;
    close $wipe_file or die $!;
    #done
}
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It would be wise to lock the file beforehand so that you know nobody else is using it at the moment. ...doesn't seem prudent to obliterate the contents of a file that's currently being read by some other process, now does it?

At any rate, opening a file for output, by default, truncates the file to zero length.

Thanks, As metioned above, the file is locked exclusive

I quote:

"To get an exclusive lock, typically used for writing, you have to be more careful. You cannot use a regular open for this; if you use an open mode of <, it will fail on files that don't exist yet, and if you use >, it will clobber any files that do. Instead, use sysopen on the file so it can be locked before getting overwritten. Once you've safely opened the file for writing but haven't yet touched it, successfully acquire the exclusive lock and only then truncate the file. Now you may overwrite it with the new data."

use Fcntl qw(:DEFAULT :flock);
sysopen(FH, "filename", O_WRONLY | O_CREAT)
    or die "can't open filename: $!";
flock(FH, LOCK_EX)
    or die "can't lock filename: $!";
truncate(FH, 0)
    or die "can't truncate filename: $!";
# now write to FH
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Cheers,
Darren

open FILE,">>filename";
truncate FILE, 0;
close FILE
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open FILE,">>filename";
truncate FILE, 0;
close FILE
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truncate works also on filenames:

$ echo abcde > file
$ perl -e 'truncate "file", 2'
$ cat file
ab
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--
David Serrano