Ubuntu how to run cmds on reboot using rc.local

Need to enable /etc/rc.local 

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

Enable /etc/rc.local on Systemd

If you type the following command in terminal:

sudo systemctl status rc-local

You may get this output:

● rc-local.service - /etc/rc.local Compatibility
 Loaded: loaded (/lib/systemd/system/rc-local.service; static; vendor preset: enabled)
 Active: failed (Result: exit-code) since Thu 2015-11-26 23:54:58 CST; 59s ago
 Process: 1001 ExecStart=/etc/rc.local start (code=exited, status=1/FAILURE)
Nov 26 23:54:57 vivid rc.local[1001]: File "/usr/lib/python2.7/dist-packages/pkg_resources/__init__.py", line 920, in require
Nov 26 23:54:57 vivid rc.local[1001]: needed = self.resolve(parse_requirements(requirements))
Nov 26 23:54:57 vivid rc.local[1001]: File "/usr/lib/python2.7/dist-packages/pkg_resources/__init__.py", line 807, in resolve
Nov 26 23:54:57 vivid rc.local[1001]: raise DistributionNotFound(req)
Nov 26 23:54:57 vivid rc.local[1001]: pkg_resources.DistributionNotFound: shadowsocks==2.8.2
Nov 26 23:54:58 vivid sudo[1008]: pam_unix(sudo:session): session closed for user root
Nov 26 23:54:58 vivid systemd[1]: rc-local.service: control process exited, code=exited status=1
Nov 26 23:54:58 vivid systemd[1]: Failed to start /etc/rc.local Compatibility.
Nov 26 23:54:58 vivid systemd[1]: Unit rc-local.service entered failed state.
Nov 26 23:54:58 vivid systemd[1]: rc-local.service failed.

And if you try to enable /etc/rc.local to run on system boot with the command:

sudo systemctl enable rc-local

You may get:

The unit files have no [Install] section. They are not meant to be enabled
 using systemctl.
 Possible reasons for having this kind of units are:
 1) A unit may be statically enabled by being symlinked from another unit's
 .wants/ or .requires/ directory.
 2) A unit's purpose may be to act as a helper for some other unit which has
 a requirement dependency on it.
 3) A unit may be started when needed via activation (socket, path, timer,
 D-Bus, udev, scripted systemctl call, ...).

The solution

As you can see from above, The unit file have no [Install] section. As such Systemd can not enable it. First we need to create a file:

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

Then add the following content to it.

[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

Save and close the file. To save a file in Nano text editor, press Ctrl+O, then press Enter to confirm. To exit the file, Press Ctrl+X.  Next, run the following command to make sure /etc/rc.local file is executable.

sudo chmod +x /etc/rc.local

Note: Starting with 16.10, Ubuntu doesn’t ship with /etc/rc.local file anymore. You can create the file by executing this command.

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

Then add execute permission to /etc/rc.local file.

sudo chmod +x /etc/rc.local

After that, enable the service on system boot:

sudo systemctl enable rc-local

Output:

Created symlink from /etc/systemd/system/multi-user.target.wants/rc-local.service to /etc/systemd/system/rc-local.service.

Now start the service and check its status:

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

Output:

● rc-local.service - /etc/rc.local Compatibility
 Loaded: loaded (/etc/systemd/system/rc-local.service; enabled; vendor preset: enabled)
 Active: active (running) since Fri 2015-11-27 00:32:56 CST; 14min ago
 Process: 879 ExecStart=/etc/rc.local start (code=exited, status=0/SUCCESS)
 Main PID: 880 (watch)
 CGroup: /system.slice/rc-local.service

use sudo /etc/rc.local to ensure /etc/rc.local cmds works.

if still getting error code, need to enable /etc/rc.local 

by running enable sudo systemctl enable rc-local

cmds in rc.local does not need sudo as 

https://unix.stackexchange.com/questions/210939/what-user-runs-the-commands-defined-in-etc-rc-local

for example 

# restart dhcp for ur network enp2s0 <network name>

# enp2s0 comes from sudo lshw –numeric –C network  

sudo dhclient enp2s0

sudo systemctl start systemd-resolved

becomes

dhclient enp2s0

systemctl start systemd-resolved

all the scripts and programs are directly called by root.

The /etc/rc.local file is called directly by the init process.