I'd like to have a script running in the background, which pings a remote host every 10 seconds or so. The script looks something like this:

nohup ping -i 10 www.google.com &

I'm able to initiate the script with an @reboot cron job, following this suggestion. However, the ping doesn't happen in the background and I don't see the script running when I poke around with ps.

Any suggestions much appreciated. Thanks.

  • 3
    if you put it like that in cron I got a question where is ping located? (answer: always use absolute paths in cron unless you can tell it to use a PATH ;) ) – Rinzwind Dec 10 '19 at 22:09
  • 1
    Try the commands with absolute paths, as described by type. The command should be /usr/bin/nohup /bin/ping -i 10 www.google.com & .BUT! is name resolution (dnsmasq) up and running when @reboot runs? Try @reboot host www.google.com. I have a different suggestion, adapt this: github.com/waltinator/net-o-matic.git - Watch for (WiFi) network going down, then do a user-specified thing to fix it. – waltinator Dec 10 '19 at 23:05
  • Why on earth do you need/want to ping google every 10 secs? – heynnema Dec 11 '19 at 0:14
  • long-ish answer, I run a high school computer lab where computers are on wifi. I am having trouble at times ssh'ing to various boxes and I'm trying to determine if the radio is timing out. Hoping that a ping keep alive will keep the wifi interface alive. I have disabled the sleep / power save, but still having trouble. it may be network traffic ... when I started this project it seemed like it would be an easy route to get a keep alive like this going in the background. And hey, I learned a bit more about Ubuntu. – ether_joe Dec 11 '19 at 1:48

I needed to switch from using a cron job, to adding a script to /etc/network/if-up.d/ as per this suggestion. Did some troubleshooting with ifup --all -v to get the details correct.

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