topic Re: For loop in Operating System - HP-UX

For loop

Zan_1 — Tue, 17 Apr 2007 06:56:49 GMT

Hello!

Can anyone help me with a case how to ping x.x.x.0 to x.x.x.255 and put the ones which are alive to a text file ??

Thanks in advance...

Re: For loop

Dennis Handly — Tue, 17 Apr 2007 07:13:06 GMT

You need a while loop:
typeset -i index=0
while [ $index -le 255 ]; do
ping xxx.$index
if [ $? -eq 0 ]; then
echo xxx.$index >> alive.file
fi
(( index=index + 1 ))
done

Re: For loop

Zan_1 — Tue, 17 Apr 2007 07:34:32 GMT

hmm.. doesn't seem to recognize typeset command...

bash-3.00# ./ping.sh
./ping.sh: typeset: not found
./ping.sh: test: argument expected

Re: For loop

Dennis Handly — Tue, 17 Apr 2007 07:42:11 GMT

>doesn't seem to recognize typeset command

A real shell recognizes typeset. I thought bash was ksh/sh like? Perhaps you should use the real shell in your scripts.

You can replace typeset by just:
index=0

Re: For loop

James R. Ferguson — Tue, 17 Apr 2007 07:42:15 GMT

Hi:

Bash uses 'declare' instead of 'typeset'.

You probably also want to amend your ping in Dennis' script to:

# ping xxx.$index -n 1

...such that only one ping is sent for each address.

Regards!

...JRF...

Re: For loop

Ralph Grothe — Tue, 17 Apr 2007 09:54:22 GMT

Nevertheless, Bash should understand a typeset declaration

$ echo $0
-bash
$ echo ${BASH_VERSINFO[*]}
3 00 15 1 release i386-redhat-linux-gnu
$ typeset -i some_int=42
$ declare -i|grep some
declare -i some_int="42"

Re: For loop

Hein van den Heuvel — Tue, 17 Apr 2007 13:43:22 GMT

For a flexible, scriptable ping usage, You might want to consider the PERL module Net::Ping

Basic docu:

http://perldoc.perl.org/Net/Ping.html

Extended example usage in attachment to Clay's note in:

http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=22018

Simple example for your case:

--------------------- ping_network.pl -----
use strict;
use Net::Ping;
my $timeout = 2;
my $network = shift;
($network =~ !/\d+\.\d+\.\d+/) or die "Please provide nextwork adrress as xx.xx.xx";
my $p = Net::Ping->new('tcp');
foreach (0..255) {
my $host = "$network.$_";
my $stat = $p->ping($host,$timeout);
# printf "%s %d %s\n", $host, $stat, $stat? 'up' : 'down';
print "$host\n" if $stat;
}
$p->close();
------------------------------

# perl ping_network.pl 192.168.1 > up.txt

Hope this helps some,
Hein van den Heuvel (at gmail dot com)
HvdH Performance Consulting

Re: For loop

Ralph Grothe — Wed, 18 Apr 2007 02:35:25 GMT

For scripting ping checkers I also prefer the Net::Ping module that Hein has introduced.
One thing noteworthy about it is
that it can be employed more universal than an ordinary ping command.
For one (as Hein demonstrated), you can emit ordinary TCP packets and thus don't require root privileges or a setuid script unlike with ICMP packets.
Even better yet, it allows you to virtually ping every service by selection of the destination port.
Albeit, if you are an OO purist you probably would frown on the Net::Ping module's bad interface that it doesn't offer a proper accessor for setting the port but rather requires the user to mangle with the Net::Ping object like so:

use Net::Ping;
my $p = Net::Ping->new('tcp');
# setting to SSH's registered port
$p->{port_num} = getservbyname('ssh', 'tcp');