Re: script or other suggestion

On 23/11/2007, Broekman, Maarten <Maarten.Broekman@xxxxxxx> wrote:
Why not just do DNS lookups to see which ones are assigned?

To build on what Cameron mentioned, just put in "host $i" in the loop
and check to see it returns anything sane. If so, you might want to
ping it to see if it's up, but as Cameron said, the system could be down
or off so that's not 100% reliable.

Maarten Broekman
Email: maarten.broekman@xxxxxxx

-----Original Message-----
From: redhat-list-bounces@xxxxxxxxxx
[mailto:redhat-list-bounces@xxxxxxxxxx] On Behalf Of Cameron Simpson
Sent: Thursday, November 22, 2007 4:10 PM
To: General Red Hat Linux discussion list
Subject: Re: script or other suggestion

On 22Nov2007 15:35, chloe K <chloekcy2000@xxxxxxxx> wrote:
| I have ip list in my network
| I need to check which ip is unused
| what is better solution?
|
| Write the ping script or use other command
|
| eg:
|
| for i in ip.txt
| ping -c 3 $i

That would be:

for i in `cat ip.txt`
do ping -c 3 $i || { echo "IP $i is not in use."; break; }
done

Of course, if a machine happens to be down/off, if will look
like its IP is not in use...

You could possibly do something clever with nmap or "ping -b",
but your approach is simple and effective.
--
Cameron Simpson <cs@xxxxxxxxxx> DoD#743
http://www.cskk.ezoshosting.com/cs/

To make matters worse, a system may be up but firewalls may block pings.

Kind regards,

Herta

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