UPDATE:
If you are getting what i think you are getting at, the Unix 'tail' command is a must for watching debug statements in your web server error log. Use the -f option which ouputs the appended data. I usually keep a terminal open right next to my browser for such occasions.

jeffa

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
F--F--F--F--F--F--F--F--
(the triplet paradiddle)

I agree that running tail on error logs is a useful development technique, but I would never do this on a live server.

tail doesn't check its output, so a malicious visitor to your Web site could send dangerous escape codes to your terminal. xterm, for example, has various features/vulnerabilities that are based on escape codes. This assumes that someone wants to attack your Web server and either knows or guesses that you are running tail on your error log, but it's always worth protecting against untrusted data on the Internet.

I just want to make the observation that this warning about the side effects of tail reflects the amazing depth and quality of answers that I have come to expect from PerlMonks. I'm impressed that someone would have provided such an insightful response to a basic question.

Dave Aiello
Chatham Township Data Corporation

Aside from the obvious "Read man tail" reply

#!/usr/bin/perl
my $lines = shift || 10;

my @buf;
while( <> ) {
  push @buf, $_;
  shift @buf if @buf > $lines 
}

print @buf;

exit 0;
[download]

--
perl -p -e "s/(?:\w);([st])/'\$1/mg"

I'm impressed!
It works really good on my w2k...
I don't know how I can have missed this great piece of code...

It's a pain trying to get the last lines of a huge log-file
on a M$-machine, but this will do the trick...

/k2

While not to disparage the PPT, you might want to have a look at the cygwin toolset for W32. It contains tail amongst many other unix tools, usable from both cmd and bash. Oh and under cmd.exe AFAIK you have no worries about using it as per earlier comments on security vulnerabilities.

Yves / DeMerphq
--
Have you registered your Name Space?

#!/usr/bin/perl -w
use strict;
use Getopt::Long;

my $line;
my $NUM;
my $FILE;

GetOptions("f=s" => \$NUM,    # -f=/var/log/messages
           "n=s" => \$FILE);  # -n=30

if (!($NUM)) {
        $NUM = 20;
}

my @TailFile = `tail -$NUM $FILE`;

foreach $line (@TailFile) {
        chomp $line;
        print "$line\n";
}
[download]

Update: My comments were flip-flopped. Corrected.

If things get any worse, I'll have to ask you to stop helping me.