Ubuntu Cheatsheet

OS

tty

• To switch ttys use ctrl + alt + F#, where # is the tty number you want to switch to.
• see Switching between ttys
  • Ubuntu 17.10+ assigns the X server to tty1 and a “dumb terminal” / “console” to tty2-7
    • older Ubuntus assign X server to tty7 instead of tty1!

Unattended Upgrade

To see if there was an unattended upgrade check /var/log/apt/history.log.

If nvidia-smi does not show the usual output check /var/log/apt/history.log because Nvidia also does some unattended upgrades, e.g.

Start-Date: 2022-12-03  06:13:58
Commandline: /usr/bin/unattended-upgrade
Upgrade: libnvidia-compute-510:amd64 (510.85.02-0ubuntu0.20.04.1, 510.108.03-0ubuntu0.20.04.1), libnvidia-compute-510:i386 (510.85.02-0ubuntu0.20.04.1, 510.108.03-0ubuntu0.20.04.1), libnvidia-encode-510:amd64 (510.85.02-0ubuntu0.20.04.1, 510.108.03-0ubuntu0.20.04.1), libnvidia-encode-510:i386 (510.85.02-0ubuntu0.20.04.1, 510.108.03-0ubuntu0.20.04.1), nvidia-kernel-common-510:amd64 (510.85.02-0ubuntu1, 510.108.03-0ubuntu0.20.04.1), xserver-xorg-video-nvidia-510:amd64 (510.85.02-0ubuntu0.20.04.1, 510.108.03-0ubuntu0.20.04.1), libnvidia-gl-510:amd64 (510.85.02-0ubuntu0.20.04.1, 510.108.03-0ubuntu0.20.04.1), libnvidia-gl-510:i386 (510.85.02-0ubuntu0.20.04.1, 510.108.03-0ubuntu0.20.04.1), libnvidia-fbc1-510:amd64 (510.85.02-0ubuntu0.20.04.1, 510.108.03-0ubuntu0.20.04.1), libnvidia-decode-510:amd64 (510.85.02-0ubuntu0.20.04.1, 510.108.03-0ubuntu0.20.04.1), libnvidia-decode-510:i386 (510.85.02-0ubuntu0.20.04.1, 510.108.03-0ubuntu0.20.04.1), libnvidia-cfg1-510:amd64 (510.85.02-0ubuntu0.20.04.1, 510.108.03-0ubuntu0.20.04.1), nvidia-utils-510:amd64 (510.85.02-0ubuntu0.20.04.1, 510.108.03-0ubuntu0.20.04.1), nvidia-dkms-510:amd64 (510.85.02-0ubuntu1, 510.108.03-0ubuntu0.20.04.1), nvidia-compute-utils-510:amd64 (510.85.02-0ubuntu0.20.04.1, 510.108.03-0ubuntu0.20.04.1), nvidia-driver-510:amd64 (510.85.02-0ubuntu0.20.04.1, 510.108.03-0ubuntu0.20.04.1), libnvidia-extra-510:amd64 (510.85.02-0ubuntu0.20.04.1, 510.108.03-0ubuntu0.20.04.1), nvidia-kernel-source-510:amd64 (510.85.02-0ubuntu0.20.04.1, 510.108.03-0ubuntu0.20.04.1)
End-Date: 2022-12-03  06:15:52

Start-Date: 2022-12-03  06:16:02
Commandline: /usr/bin/unattended-upgrade
Upgrade: libnvidia-common-510:amd64 (510.85.02-0ubuntu1, 510.108.03-0ubuntu0.20.04.1)
End-Date: 2022-12-03  06:16:03

Shortcuts

Disable Annoying Gnome Shortcuts

• emoji autocomplete popup: ctrlshifte (annoying when using IntelliJ)
  • run ibus-setup, there you can remove this shortcut under “Emoji” → “Keyboard Shortcuts”, unix.stackexchange

For Bluetooth Settings Icon in Ubuntu Activities

• Create .desktop file (.desktop ending required!) with this content

[Desktop Entry]
Name=open_bluetooth_settings
Exec=gnome-control-center bluetooth
Terminal=false
Type=Application

• Make sure that your script is executable, like this:

sudo chmod +x /path/to/script.sh  

(if it does not execute, copy it to ~/Desktop/. There right-click on it and select “Allow Launching”.)

• Move .desktop file to /usr/share/applications/. Press Super to open Activities and in the application grid view select “All” (instead of “Frequent”) and search the created .desktop file there. Right-click on it and select “Add to Favorites”. Now the .desktop file should be in the dock and can be accessed via shortcut Super + <position_in_dock>.
• Warning: It won’t work if your script uses the sudo command, or anything else that requires user input.

If you want it to open a terminal window when you run it (if you needed to add input or watch the output) set Terminal to true.

Terminal=true

Nautilus

Press F4 to open the current directory in the terminal:

• see askubuntu
  • note: do not forget chmod +x Terminal

Network

On the server computer:

1. Connect server and client via Ethernet cable.
2. On the computer, which is connected to the Internet, click the network icon in the panel and go to “Settings” at the bottom of the menu. [der Schieberegler von “Wired” beim Server sollte bereits aktiv sein, der Schieberegler beim Client sollte inaktiv sein (auch nachdem Kabel eingesteckt wurde)]
3. Click on the “Settings symbol” of your Wired Connection (Leave your wireless connection untouched).
4. On the “IPv4 Settings tab”, select Method: “Shared to other computers”. Click on “Apply” and close this window.
5. On the server reconnect by clicking on the Wired Network’s toggle switch [dh. einmal aus und an], so it gets a new IP address. (The two computers must be connected by an ethernet cable for this step, so connect them now if you haven’t already.) [Toggle Switch auf Client sollte noch inactive sein]
6. Do not change IP settings. Leave everything as it is.

On the client computer:

1. Connect simply via toggle switch of Wired Connection. IP settings are configured automatically!

Mostly from: Instructions

Power

• source The Settings which determine what happens, when the Battery Level is critically low are in /etc/UPower/UPower.conf. There, the relevant entries are:

  PercentageAction=2
  CriticalPowerAction=HybridSleep
  

• for laptops: source
  • cat /sys/class/power_supply/BAT0/capacity outputs laptop battery level (in percent)
  • cat /sys/class/power_supply/BAT0/status outputs laptop battery status (values: “Unknown”, “Charging”, “Discharging”, “Not charging”, “Full”)
  • cat /sys/class/power_supply/BAT0/capacity_level outputs laptop battery level description (values: “Unknown”, “Critical”, “Low”, “Normal”, “High”, “Full”). From doc: “Coarse representation of battery capacity.”

Gnome Shell

Extensions

extensions.gnome.org

Here you can manage all extensions installed on your machine.

Installed Extensions

List installed extensions using

# all
gnome-extensions list

# locally installed
ls .local/share/gnome-shell/extensions/

# system wide installed
ls /usr/share/gnome-shell/extensions/

# local
compiz-alike-magic-lamp-effect@hermes83.github.com
disableworkspaceanim@owilliams.mixxx.org
harddiskled@bijidroid.gmail.com
jiggle@jeffchannell.com
noannoyance@daase.net
panel-osd@berend.de.schouwer.gmail.com
switchWorkSpace@sun.wxg@gmail.com
user-theme@gnome-shell-extensions.gcampax.github.com
weeks-start-on-monday@extensions.gnome-shell.fifi.org

# system wide
desktop-icons@csoriano
ubuntu-appindicators@ubuntu.com
ubuntu-dock@ubuntu.com

Launch new instance when there is no instance open ON CURRENT WORKSPACE

E.g. if a gedit instance is already open on some workspace, if you open a new instance, Ubuntu will always switch to that workspace first before opening the new instance which is presumably not what you want.

To change this behaviour: From askubuntu

gsettings set org.gnome.shell.extensions.dash-to-dock isolate-workspaces true

Remove “Window is ready” popup and focus window

see NoAnnoyance v2

Switch Workspace with Ctrl+AboveTab

see Switch Workspace

Gnome-Terminal

command	description
gnome-terminal --title="TITLE"

Tracker

see wiki.ubuntuusers.de

Troubleshooting

Try everything on this page.

Show the Tracker status:

$ tracker status
Currently indexed: 1458 files, 227 folders
Remaining space on database partition: 7,4 GB (5,92%)
Data is still being indexed: Estimated less than one second left

To see where Tracker hangs (here: see the last line in the output below):

$ tracker daemon
Store:
27 Mär 2023, 01:02:26:  ✗     Store                - Unavailable

Miners:
27 Mär 2023, 01:02:26:  ✗     Extractor            - Not running or is a disabled plugin
27 Mär 2023, 01:02:26:    1%  File System          - Crawling recursively directory 'file:///home/bra-ket/Desktop/react/tutorial/node_modules/@jest/expect-utils' 

Last time the solution was:

Über GUI Konfigurieren

Aufruf über Einstellungen -> Suchen. Dort gibt es oben in der Titelleiste den Button "Orte durchsuchen" über den Konfiguriert werden kann welche Verzeichnisse durchsucht werden sollen. Diesen Button habe ich die ersten Male auf der Einstellungsseite völlig übersehen.

In this GUI excluding the “Home” folder stopped tracker-miner-fs which was stuck (see above in the output of “tracker daemon”) and had about 95% CPU in htop.

Storage

Disk

baobab aka Disk Usage Analyzer

duck

supports many “protocols” like Google Drive, Dropbox, Amazon S3, OneDrive, ownCloud, WebDAV, etc

TODO: duck CLI commands

doc: duck CLI

mega.io CLI

github repo

UserGuide

install:

wget https://mega.nz/linux/repo/xUbuntu_20.04/amd64/megacmd-xUbuntu_20.04_amd64.deb && sudo apt install "$PWD/megacmd-xUbuntu_20.04_amd64.deb"

There is a “interactive mode” (like python repl) and a “scriptable mode”.

list of commands

Login

command	description
mega-login email password	where ! in password must be escaped with backslash

Storage Space Management

• Unlike Git, in mega a file version that has a size of X MB will use X MB space! (You can check this via mega-du --versions.)

command	description
mega-du -h	Prints size used by files/folders
mega-du --versions -h remotefile	total size of all file versions of remotefile together

Upload

command	description
mega-put localfile remotedest	upload localfile, where localfile is relative to the current directory of the shell (not relative to mega-lpwd!), automatically creates a new version of localfile if it is already existing in the remote

Download

command	description
mega-ls -lh dir/	list of files with size, Modification date for files and creation date for folders (see mega-ls --help)
mega-ls --versions remotefile	list versions of remotefile (warning: mega supports only 100 file versions! mega uses a smart algorithm to decide which version to remove first, see help.mega.io)
mega-ls -lh --versions remotefile	list versions and sizes of remotefile
mega-get remotefile	download the latest version of remotefile into the current directory
mega-get remotefile#1723078907	download the version #1723078907 of remotefile into the current directory

Remote File Operations

command	description
mega-cp remote/src/path/ remote/dest/path/	only for copying remote files (you cannot mega-cp local files to the remote! use mega-put for that)
mega-rm remotefile	remove all versions of remotefile
mega-rm remotefile#1723078907	remove a specific version of remotefile, workaround to remove the latest version (A): STEP 1: download and upload the previous version (B), STEP 2: then the latest version (A) is assigned an ID so that you can mega-rm remotefile#1723078907 on the ID of the latest version (A), STEP 3: then delete the previous version (B) (which is unnecessary now because you have uploaded the same file in STEP 1)
mega-mkdir remotefolder	create a new folder remotefolder on the remote (warning: do not use a trailing slash behind the foldername like in mega-mkdir remotefolder/ or you will get an error Use -p to create folders recursively)

Interactive Mode

command	description
mega-lpwd	only used for “interactive mode”, whereas in “scriptable mode” the current directory of the shell is used as lpwd

Appearance

Restart GUI

Press Alt + F2, then type r and press Enter.

other methods: https://linuxconfig.org/how-to-restart-gui-on-ubuntu-20-04-focal-fossa

Dock like MacOS

gsettings set org.gnome.shell.extensions.dash-to-dock extend-height false

gsettings set org.gnome.shell.extensions.dash-to-dock show-show-apps-button false 

gsettings set org.gnome.shell.extensions.dash-to-dock show-trash true

• add Launcher icon to dock: via .desktop icon to favorites using “launch show-apps from command line”

Hide Dock permanently

see source Option 3

Hide:

gsettings set org.gnome.shell.extensions.dash-to-dock autohide false

gsettings set org.gnome.shell.extensions.dash-to-dock dock-fixed false

gsettings set org.gnome.shell.extensions.dash-to-dock intellihide false

Show:

gsettings set org.gnome.shell.extensions.dash-to-dock autohide true

gsettings set org.gnome.shell.extensions.dash-to-dock dock-fixed true

gsettings set org.gnome.shell.extensions.dash-to-dock intellihide true

Set Default Applications

Config files

• /usr/share/applications/defaults.list (root)
• /etc/gnome/defaults.list (root)
• ~/.config/mimeapps.list (local user)

Change default app

Using xdg-settings

xdg-settings set default-web-browser firefox.desktop

Using xdg-mime

Get:

# To view the current default for opening directories:
xdg-mime query default inode/directory

Set:

xdg-mime default some_app some_filetype

E.g.

xdg-mime default org.kde.okular.desktop application/pdf

# To set Dolphin as default file manager:
xdg-mime default org.kde.dolphin.desktop inode/directory

creates an entry in the local MIME database ~/.config/mimeapps.list.

Change default mail client

If not already present, add

MimeType=x-scheme-handler/mailto;x-scheme-handler/mailspring;

to ~/.local/share/applications/mailspring_mailspring.desktop and run

update-desktop-database ~/.local/share/applications

There should be a new line x-scheme-handler/mailto=mailspring_mailspring.desktop in ~/.config/mimeapps.list now.

“Open with …” and set default app for a given file

For xdg-open

xdg-mime default some_app some_filetype (see above)

For mimeopen

mimeopen -d myfile.pdf

will give you a list of applications that can open the file, and (the -d flag) will also update the default application for you. Note: After running this command the default works for mimeopen myfile.pdf only. xdg-open myfile.pdf and nautilus defaults need to be specified via xdg-mime default some_app some_filetype (see above)!

File Manager

Dolphin

sudo apt install dolphin

sudo nvim /usr/share/applications/org.kde.dolphin.desktop

# in org.kde.dolphin.desktop set:
Exec=dolphin %u --new-window

Pager

Nano

• M-U means “Meta Key” + Alt. The “Meta key” is not present on most keyboards. (Its use in software is for primarily historical reasons.) Usually, the meta key is emulated by another key on your keyboard. On Windows and Linux, it is usually the Alt key. On Mac OS X, that key (aka Option) already has other uses, and so Escape is used instead.

Most

• set most as default pager is .bashrc to get coloured man pages

Converter

pptx (or ppt) to pdf

• libreoffice --headless --invisible --convert-to pdf *.ppt

Sound

List all microphones:

sudo arecord -l

Record an audio file /tmp/test-mic.wav with 10s duration, where hw:2,0 means using card 2 and device 0 (as shown by arecord -l):

arecord -f cd -c 1 -d 10 --device="hw:2,0" /tmp/test-mic.wav

Play an audio file /tmp/test-mic.wav:

aplay `/tmp/test-mic.wav`

Troubleshooting

Problem 1: No sound in Totem Videos:

• let the video that has no sound play in Totem
• open Ubuntu Sound Settings
• under section “Volume Levels” below eg. “System Sounds”, “Firefox”, etc. a new item for the currently playing video will be shown
• check if the Volume for this video is enabled and is sufficiently high
• in addition, check the Volume in the Totem Video App

Webcam

Troubleshooting

Flickering

• caused by 50Hz vs 60Hz powerline frequency differences (see source)
  • solution: try v4l2-ctl --set-ctrl power_line_frequency=0 or v4l2-ctl --set-ctrl power_line_frequency=1

buku

Bookmark Manager

pip3 install buku
pip3 install flask # fixes error
# gui
pip3 install "buku[server]"
# start bukuserver, open in firefox
bukuserver run --host 127.0.0.1 --port 5001
# import firefox bookmarks
buku --import ~/Downloads/bookmarks27jan24.html

# OR
buku -t tag1, tag2

# AND
buku -t tag1 + tag2

# NOT
buku -t tag1 - tagToExclude1, tagToExclude2

# add tags
buku -t tag1 -s pattern -u --tags + newTag

# print just urls
buku -t tag1, tag2 -f 1

rofi

Install

Follow the steps in autotools and checkout.

git clone --recursive https://github.com/DaveDavenport/rofi
cd rofi
git checkout tags/1.7.5
autoreconf -i
mkdir build
cd build/
# run this multiple times to check which dependencies are missing until 
# you have installed all missing dependencies
../configure --disable-check
make
sudo make install

Select sidebar by Qball theme with “Rofi Theme Selector” (type “Rofi Theme Selector” in Ubuntu “Activities overview”).

sudo nvim /usr/local/share/rofi/themes/sidebar.rasi and change

window {
    height:   100%;
    //width: 30em;
    width: 100%;
    location: west;
    anchor:   west;
    border:  0px 2px 0px 0px;
    text-color: @lightwhite;
}

In Ubuntu Settings create a new Shortcut (press '+' button at the bottom to create a custom shortcut):

• bind super + b to command rofi -show bookmarksTree.

PDF Reader

Okular

Shortcuts

command	description
F6	toggle annotation tools bar
F7	toggle page preview pane
ctrl + m	toggle menu bar
ctrl + shift + ,	configure okular
ctrl + e	configure shortcuts

Annotation Tools

Configure annotation tools via GUI:

• right click on the annotation widget/bar (F6 to toggle the annotation widget/bar)

Configure annotation tools via tools.xml:

/usr/share/okular/tools.xml

Examples:

<annotation type="GeomSquare" width="1" color="#FF6868" />

<tool type="note-linked" id="1">
    <engine hoverIcon="tool-note" type="PickPoint" color="#ffff88">
        <annotation icon="Note" type="Text" color="#ffff88" />
    </engine>
    <shortcut>1</shortcut>
</tool>,
<tool type="note-inline" id="2" name="Inline Left 14 Mono">
    <engine hoverIcon="tool-note-inline" block="true" type="PickPoint" color="#ffffdd">
        <annotation opacity="0.85" type="FreeText" color="#ffffdd"
            font="Monospace\\,14\\,-1\\,5\\,50\\,0\\,0\\,0\\,0\\,0" />
    </engine>
    <shortcut>2</shortcut>
</tool>,
<tool type="highlight" id="3">
    <engine type="TextSelector" color="#ffff00">
        <annotation type="Highlight" color="#ffff00" />
    </engine>
    <shortcut>3</shortcut>
</tool>,
<tool type="highlight" id="4" name="Highlighter (pale)">
    <engine type="TextSelector" color="#ffff00">
        <annotation opacity="0.3" type="Highlight" color="#ffff00" />
    </engine>
    <shortcut>4</shortcut>
</tool>,
<tool type="underline" id="5">
    <engine type="TextSelector" color="#000000">
        <annotation type="Underline" color="#000000" />
    </engine>
    <shortcut>5</shortcut>
</tool>,
<tool type="underline" id="6">
    <engine type="TextSelector" color="#da0000">
        <annotation opacity="0.7" type="Underline" color="#da0000" />
    </engine>
    <shortcut>6</shortcut>
</tool>,
<tool type="straight-line" id="7">
    <engine points="2" type="PolyLine" color="#ff4a26">
        <annotation width="4" opacity="0.8" type="Line" color="#ff4a26" />
    </engine>
    <shortcut>7</shortcut>
</tool>,
<tool type="rectangle" id="8">
    <engine block="true" type="PickPoint" color="#ffff00">
        <annotation width="5" opacity="0.1" innerColor="#ffff00" type="GeomSquare" color="#ffff00" />
    </engine>
    <shortcut>8</shortcut>
</tool>,
<tool type="ellipse" id="9">
    <engine block="true" type="PickPoint" color="#00ffff">
        <annotation width="5" type="GeomCircle" color="#00ffff" />
    </engine>
    <shortcut>9</shortcut>
</tool>,
<tool type="ink" id="10" name="Freehand Line (2.0\\, black)">
    <engine type="SmoothLine" color="#000000">
        <annotation width="2" type="Ink" color="#000000" />
    </engine>
</tool>,
<tool type="ink" id="11" name="Freehand Line (2.0\\, Red)">
    <engine type="SmoothLine" color="#ff0000">
        <annotation width="2" type="Ink" color="#ff0000" />
    </engine>
</tool>,
<tool type="polygon" id="12">
    <engine points="-1" type="PolyLine" color="#007eee">
        <annotation width="1" type="Line" color="#007eee" />
    </engine>
</tool>,
<tool type="ink" id="13" name="Freehand Line (1.0\\, blue)">
    <engine type="SmoothLine" color="#0000ff">
        <annotation width="2" type="Ink" color="#0000ff" />
    </engine>
</tool>,
<tool type="stamp" id="14">
    <engine hoverIcon="bookmarks" size="64" block="true" type="PickPoint">
        <annotation opacity="0.5" icon="bookmarks" type="Stamp" />
    </engine>
</tool>,
<tool type="strikeout" id="15">
    <engine type="TextSelector" color="#c00000">
        <annotation opacity="0.8" type="StrikeOut" color="#c00000" />
    </engine>
</tool>,
<tool type="rectangle" id="16">
    <engine block="true" type="PickPoint" color="#ff0000">
        <annotation width="5" opacity="0.1" innerColor="#ffff00" type="GeomSquare" color="#ff0000" />
    </engine>
</tool>,
<tool type="note-inline" id="17" name="Heading Centre 48 Opaque">
    <engine hoverIcon="tool-note-inline" block="true" type="PickPoint" color="#ffffff">
        <annotation type="FreeText" color="#ffffff"
            font="Sans Serif\\,48\\,-1\\,5\\,50\\,0\\,0\\,0\\,0\\,0" align="1" />
    </engine>
</tool>,
<tool type="note-inline" id="18" name="Inline Center 12">
    <engine hoverIcon="tool-note-inline" block="true" type="PickPoint" color="#ffffee">
        <annotation opacity="0.85" type="FreeText" color="#ffffee"
            font="Sans Serif\\,12\\,-1\\,5\\,50\\,0\\,0\\,0\\,0\\,0" align="1" />
    </engine>
</tool>,
<tool type="polygon" id="19" name="Red Filled Polygon">
    <engine points="-1" type="PolyLine" color="#ff4a26">
        <annotation width="1" opacity="0.8" innerColor="#ff4a26" type="Line" color="#ff4a26" />
    </engine>
</tool>,
<tool type="polygon" id="20" name="Whiteout Poly">
    <engine points="-1" type="PolyLine" color="#ffffff">
        <annotation width="1" innerColor="#ffffff" type="Line" color="#ffffff" />
    </engine>
</tool>,
<tool type="note-inline" id="21" name="Inline Left 10 Mono">
    <engine hoverIcon="tool-note-inline" block="true" type="PickPoint" color="#ffffdd">
        <annotation opacity="0.85" type="FreeText" color="#ffffdd"
            font="Monospace\\,10\\,-1\\,5\\,50\\,0\\,0\\,0\\,0\\,0" />
    </engine>
</tool>,
<tool type="note-inline" id="22" name="Inline Left 6 Mono">
    <engine hoverIcon="tool-note-inline" block="true" type="PickPoint" color="#ffffdd">
        <annotation type="FreeText" color="#ffffdd"
            font="Monospace\\,6\\,-1\\,5\\,50\\,0\\,0\\,0\\,0\\,0" />
    </engine>
</tool>