Forgive my expertise in Linux, but is there a way to run a command on another Raspbian card? Suppose I setup a command file on RPi #2, and want to run it from RPi #1. A command like:
tell RPi2 "ntpq -pn"
perhaps with the output coming to my terminal. Of course, I could do this with ssh-ing into RPi-2, but I would like to avoid the ssh step.
Likely it's obvious, but not (yet) to me!
Well, for that case it is not required because you can do:
ntpq -pn RPi2
When that does not work, go to RPi2 and add in the /etc/ntp.conf:
restrict aa.bb.cc.dd
(the IP address of RPi1) Then restart ntpd (or the entire Pi)
That does not restrict that address, it lifts the restrictions on who can run external queries.
However, when you want to run other commands, you can use ssh:
ssh user@RPi2 command
What is wrong with "ssh RPi2 ntpq -pn"? You need not log in to the remote Pi but can pass a single command to the ssh command. Once you managed to copy your key to the second machine (man ssh-copy-id) you need no password either.
indeed, you were so close!
ssh user@RPi2 "ntpq -pn"
password can be avoided by using public key based authenticaqtion, if that fits with your security model
Thanks, Rob, Peter & Jasen. You've just saved me quite a lot of effort.
Rob, yes, ntpq was a poor choice of command! It's actually an automated ntp update which I run as "./update-ntp"
Peter, thanks for the pointer to ssh-copy-id. Worthy of further investigation.
Jasen, thanks for the information.
I can confirm that what you have all suggested works perfectly for me.
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