Linux (Ubuntu) Cheatsheet

Useful commands and tips about system operation. Things more about scripting are in Bash Cheatsheet

`systemctl`

Where are service files? #

/etc/systemd/system/service-name.service

text

Start at Boot #

sudo systemctl enable sshd.service

bash

disable is the opposite.

Use Environment in Service Unit File #

[Service]
Environment=PATH=/home/pi/.local/bin:/home/pi/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin

ini

Note
$PATH do not have its special meaning here.
https://askubuntu.com/questions/1014480/how-do-i-add-bin-to-path-for-a-systemd-service for advanced.

Unit File Template #

Click to expand

[Unit]
Description=Jupyter Notebook

[Service]
Type=simple
PIDFile=/run/jupyter.pid
Environment=PATH=/home/pi/.local/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
ExecStart=jupyter lab --config=/home/pi/.jupyter/jupyter_notebook_config.py
User=pi
Group=pi
WorkingDirectory=/home/pi/Notebooks/
Restart=always
RestartSec=10
#KillMode=mixed

[Install]
WantedBy=multi-user.target

ini

Exited Without Error Log? #

From https://unix.stackexchange.com/questions/225401/how-to-see-full-log-from-systemctl-status-service/225407

Use journalctl command. e.g.

journalctl -u service-name.service

bash

-u is short for --unit. More useful options:

-f, --follow: Show only the most recent journal entries, and continuously print new entries as they are appended to the journal.
-r, --reverse: Reverse output so that the newest entries are displayed first.

`apt`

List All Versions #

https://askubuntu.com/questions/473886/list-all-versions-of-a-package

apt-cache madison chromium-browser
# or
apt-cache showpkg lyx

bash

Install Specific Version #

https://askubuntu.com/questions/428772/how-to-install-specific-version-of-some-package

# get version of installed package
apt-cache policy <package name>
# install a specific package version
sudo apt-get install <package name>=<version>

bash

OS Release Info #

cat /etc/os-release

bash

List All Users #

less /etc/passwd

bash

`lsof`

LiSt Open Files. A very powerful tool.

For network checking:

ls -i [46][protocol][@hostname|hostaddr][:service|port]

text

e.g.

sudo lsof -i :80

shell

`find`

find -iname 'qwerty'
find dir/ -iname 'qwerty'
find -name 'Qwerty'

bash

No Wireless Connection After Sleep #

sudo service network-manager restart

bash