Very nice.
However, it strips the last \n from the file (which probably isn't desirable) and it truncates non-whitespace data if there isn't a final \n. Which means that if you run the program twice in a row it will strip non-whitespace data from the end of the file.
Also, your tell() is followed by a read() so the next seek() starts from the EOF again and not from $cur_pos. ;-)
The following changes fix these problems:
#!/usr/bin/perl -w
use strict;
my $file = shift or die;
open my $fh, "+<$file" or die "$!";
binmode $fh; # Just in case
my $size = 4096;
my ($cur_pos, $buf);
seek $fh, -$size, 2;
while (1) {
$cur_pos = tell $fh;
read $fh, $buf, $size;
last if $buf =~ m/\S/s;
seek $fh, -$size*2, 1;
}
$buf =~ m/(\s+)$/s;
$cur_pos += $-[0] || 0;
truncate $fh, ++$cur_pos if $cur_pos;
close $fh;
exit 0;
--
John.
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