Hi all, In daemontools-inspired inits, you express dependencies via if statements in the run script. The best way I've found, so far, to do this in Devuan is to use the following script, called netup.sh:
======================================== #!/bin/sh echo 'quit' | nc -w2 $1 $2 2>/dev/null 1>/dev/null return $? ======================================== The nc command was already installed on my from-the-factory Devuan. This could be used in a run script as follows: ======================================== #!/bin/sh if netup.sh google.com 80; then exec sshd -d fi sleep 1 ======================================== Or, more tersely: ======================================== #!/bin/sh netup.sh google.com 80 && exec sshd -d sleep 1 ======================================== The reason I used nc instead of ping is that in many virtual machine host situations, you can't ping something on the Internet but you can nc it. So this works both on metal and virtual. The -w2 arg to nc limits response time to 2 seconds, instead of hanging for an inordinate amount of time. If a server hasn't responded within 2 seconds, there's something wrong anyway. Obviously, this could be used to test any server for some sort of response to any port. Of course, if you wanted a specific response, you'd probably use a test more specific to the service provided by the host. SteveT Steve Litt July 2017 featured book: Quit Joblessness: Start Your Own Business http://www.troubleshooters.com/startbiz _______________________________________________ Dng mailing list Dng@lists.dyne.org https://mailinglists.dyne.org/cgi-bin/mailman/listinfo/dng
