a question on return codes

[mace]

I have a process that does a ping to a server before it transmits backup data.
This tells me if the server is up or down.
I know that if I code something and it is good I get a 0 and if bad I get a 1.
Now for my question:

The ping is going to return something either good responses(response times) or a response that it timed out.
Is there a way that if the ping returns with times(good) then the ftp world start and if it fails then the ftp would not proceed.
Any ideas
thanks
mace

[lomcevak]

Try this:

ping -c 1 <IP_address>
if [ $? -eq 0 ]
   then ftp <whatever...>
   else echo "Server did no respond"
   fi

[Cabhan]

I think that lomcevak has misunderstood.

So you are saying that you will get some specific exit code if it is bad, and anything else means it is good. In that case, basically do the opposite of what he said:

ping IP_ADDRESS
ping_return=$?

if [ "$ping_return" -neq "$bad_return" ]; then
    # do your FTP stuff
else
    # ping returned bad response
fi

Does this make sense?

[drl]

Hi.

If ping does not receive any reply packets at all it will exit with
code 1. If a packet count and deadline are both specified, and fewer
than count packets are received by the time the deadline has arrived,
it will also exit with code 1. On other error it exits with code 2.
Otherwise it exits with code 0. This makes it possible to use the exit
code to see if a host is alive or not.

-- excerpt from man ping

So I think lomcevak's response is correct -- "0" is OK in scripting. Other values are not standardized, and there are at least 2 non-zero exit codes from ping. The deadline or timeout may be useful to specify, for example:

ping -c 1 -W 1 microsoft.com

returns with exit code 1 after 1 second. Otherwise, the default seems to be 10 seconds.

You may wish to discard the ping printable output, but that's something you can do once you get your code running correctly ... cheers, drl