Re: Checking if the network is up

[Buddha Buck <phaedrus@dreamscape.com>]

> Hi,
> I am trying to write a script to use popclient to download the mail from
> the office's server. This will run on a portable. I want the script to
> check whether the network is up before attempting to retrieve any mail,
> as I am likely to use the notebook in other places and won't be hooked
> to the network.
> 
> The question is:
> 
> Is there any way of checking whether the network is responding so that I
> only run popclient when it is?

Yes, there are probably a number of ways.

You could check the output of netstat -r for a default route (something 
like 
"[ `netstat -rn | grep '^0\.0\.0\.0' | wc --lines`  = 0 ] || 
popclient...", although there is probably an easier way to do that)

I have set it up so that on my system, bringing up my PPP connection 
automatically creates a "/var/lock/ip-is-up", and bringing it down 
deletes that file.  Since I only have a single net connection, this 
works.  For multiple net connetions, some modification might have to be 
done.

There are probably others, but I don't know them offhand.

One final note:  I don't use a lap-top, but my computer is also not 
connected to the internet fulltime.  However, I run two popclients 
every 5 minutes via a cron entry.  I've decided that I don't need to 
have then even check for the net connection first.  Since popclient 
aborts very quickly when it can't establish a connection, I don't even 
notice that i have them running.  Will this not work for you, too?

> 
> Thanks.
> Luis.
> 

-- 
     Buddha Buck                      bmbuck@acsu.buffalo.edu
"She was infatuated with their male prostitutes, whose members were
like those of donkeys and whose seed came in floods like that of
stallions."  -- Ezekiel 23:20