Bash Code Linux

How I delay code execution in Bash until a remote host is responding

David Both
0

I have recently been working on some code that needs to run on a remote host using SSH. I describe this in my article, Using tar and ssh for backups.

But now I need to reboot the remote computer and wait until it has completely rebooted and the network is up and running. Only after that occurs can I continue sending commands to that remote system.

This little bit of code accomplishes that for me.

Host="f41vm"
X=1

until [ $X -eq 0 ] ; do
      sleep 10s 
      ping -c1 $Host 
      X=$?
done

# The rest of the code is executed starting here, 
# when the ping is successful and 
# returns 0 instead of 1.

The X=$? statement takes the return code of the ping command ( $?_ ) and sets the $X variable to that value. Then $X can be used in the until statement comparison expression.

I add the sleep command so I’m not sending a Bazzillion pings to the remote host, and 10 seconds seems to work well enough for most of my purposes.

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