How can I execute command on startup (rc.local alternative) on Ubuntu 16.10

Intro

I think you should not create a new service as suggested in the link by George. The rc-local.service already exists in systemd and the service file suggests that the rc.local, if it exists and is executable, gets pulled automatically into multi-user.target. So no need to recreate or force something that is just done in another way by the systemd-rc-local-generator.

One solution

A quick solution (I don't know if that's the canonical way):

In a terminal do:

printf '%s\n' '#!/bin/bash' 'exit 0' | sudo tee -a /etc/rc.local
sudo chmod +x /etc/rc.local
sudo reboot

After that the rc.local will be called upon system startup. Insert what you like.

Background

If you do in a terminal:

sudo systemctl edit --full rc-local

You can see that the head comment contains lines such as:

# This unit gets pulled automatically into multi-user.target by
# systemd-rc-local-generator if /etc/rc.local is executable.

This indicates, that in this system, if there is a file called /etc/rc.local which is executable, then it will be pulled into multi-user.target automatically. So you just create the according file (sudo touch...) and make it executable (sudo chmod +x ...).

I saw this solution suggested which involves use of systemd here:

1. Create a service:

   sudo vi /etc/systemd/system/rc-local.service
   

2. Add your code there:

   [Unit]
   Description=/etc/rc.local Compatibility
   ConditionPathExists=/etc/rc.local
   
   [Service]
   Type=forking
   ExecStart=/etc/rc.local start
   TimeoutSec=0
   StandardOutput=tty
   RemainAfterExit=yes
   SysVStartPriority=99
   
   [Install]
   WantedBy=multi-user.target
   

3. Create and make sure /etc/rc.local is executable and add this code inside it:

   sudo chmod +x /etc/rc.local

   #!/bin/sh -e
   #
   # rc.local
   #
   # This script is executed at the end of each multiuser runlevel.
   # Make sure that the script will "exit 0" on success or any other
   # value on error.
   #
   # In order to enable or disable this script just change the execution
   # bits.
   #
   # By default this script does nothing.
   
   exit 0
   

4. Enable the service:

   sudo systemctl enable rc-local
   

5. Start service and check status:

   sudo systemctl start rc-local.service
   sudo systemctl status rc-local.service
   

6. If all goes well you can add your code to the /etc/rc.local file then restart it.

Note: Tested on Lubuntu 16.10.

Source:

https://www.linuxbabe.com/linux-server/how-to-enable-etcrc-local-with-systemd