I want to try to use ping to detect if a server goes down. So the idea was to have something ping forever, and then if ping ever timed out( -W flag) it would return and I'd be able to detect it. But if I ping an unreachable address ping just seems to block forever, where i'd expect it to time out and return.
ping 1.1.1.1 -W 1 -v
PING 1.1.1.1 (1.1.1.1) 56(84) bytes of data.
^C
--- 1.1.1.1 ping statistics ---
10 packets transmitted, 0 received, 100% packet loss, time 9071ms
ping was not blocked, it just didn't showed you the failed transmissions while it was running.
Take a look at the statistics when you stopped it.
10 packets transmitted, 0 received, 100% packet loss, time 9071ms
You see packets were transmitted but not received. You ran it for ~10 seconds and it transmitted 10 packets and waited for 1 second for the timeout period you mentioned before sending the next packet.
If you want to visualize the failed transmissions you can use the -f option with a suitable ping interval using the option -i interval. The value of interval should be greater than 0.2 seconds. You can find more details of it the manual page of ping by running man ping.
ping -f -i .5 -W 1 1.1.1.1
Will produce an output like this.
PING 1.1.1.1 (1.1.1.1) 56(84) bytes of data.
.......^C
--- 1.1.1.1 ping statistics ---
7 packets transmitted, 0 received, 100% packet loss, time 3048ms
Where each . represents a transmission without any reply and in case of a reply one backspace will be printed removing a ..
I think this is the kind of solution you are looking for. An automated script for periodically checking the connectivity.
