I have a script inside of /etc/init.d/wifi and I want to start it on boot. I first gave it permissions by running sudo chmod 755 wifi, then I ran sudo update-rc.d wifi defaults. Finally, I enabled it with wifi enable and it worked perfectly. However, when I did a reboot, the service wasn't active.
Why? What am I missing? I'm using Debian 9.
First, tell systemd about the service:
systemctl daemon-reload
This should create a mapping from your initV startup to a systemd unit file. Now you should get some sensible output when you run....
systemctl status wifi
You will probably need to enable the service:
systemctl enable wifi
Although this does not address the complexities of ensuring it is started at the right point during initialization - i.e. before services which rely on the network. Indeed its very unusual to start the network up this way. Typically there is another layer of abstraction between systemd and the network handled by ifupdown, networkManager or similar.
I think you forgot to create a symlink to /etc/rc.d
See Jonathan Muller's answer to this exact question over on stack overflow
update-rc.d.
update-rc.d sysinit is the old-style fashion to deal with services @boot time.
Now you need to deal with systemd.
You can create a systemd script.
Another 'hack' is to add your script to /etc/rc.local, that way, it will be executed at boot time.
rc? Or are you using systemd? If the latter, your question should contain the output ofsystemctl status wifi. In either case, your question should also show the descriptive comment block in the script, that is usually at the beginning.