Home

Commands

Applications git imagemagick mongod GNOME gsettings gconf-editor KDE kquitapp krunner kstart SMB smbclient smbpasswd smbstatus

[Printing] [CUPS][CUPS] cupsaccept cupsenable cupsdisable cupsreject lp cancel LPD lpc lpq lpr lprm

Kubernetes kubeadm kubectl

Linux distributions and desktop environments

KDE

Appearance

• Colors affects the appearance of text
• Workspace Theme > Look and Feel allows selection of Look and Feel Themes that affect window appearance
• Workspace Theme > Plasma theme appears to affect the appearance of widgets only

Comparison with other OSes

File dialogs have highly configurable views, with icon sizes scalable from 16 to 128 px and filenames available to the side or below the icon.

• A view similar to the Icons view in Mac OS X or the List view in Windows can be reproduced by setting View to the icon size to the minimum 16px and placing the filename to the side (Icon Position > Next to file name)

Wallpapers

Wallpaper types "Haenau" and "Hunyango" are QML (Qt Modeling Language) animated wallpapers that were introduced in Plasma 5.1 (2014)

Widgets

"Plasmoids" are dragged and dropped onto the Desktop, where they function as buttons. A long click will allow them to be moved, rotated, or resized. Each plasmoid can be configured with a keyboard shortcut. They occupy all virtual desktops.

One plasmoid in particular is the "Grouping Plasmoid", which allows other plasmoids to be placed within it, where they occupy separate tabs.

Login manager

Workspace > Startup and Shutdown > Login Screen (SDDM)

• The advanced tab allows you to select Mouse cursor theme and auto login of user and session type. These appear to affect specifically settings in /etc/sddm.conf (Session=gnome-xorg under [Autologin])

Default shortcuts are found in Workspace > Shortcuts > Global Shortcuts

• "Run Command" refers to krunner, a single-line application launcher similar to the Run command on Windows.
• Alt-t : open a terminal window

System logging

Traditionally, syslogd was the daemon in charge of this, but recently alternatives such as rsyslog and syslog-ng have emerged.

#	Severity	Description
0	Emergencies	Most severe error conditions that render the system unusable
1	Alerts	Conditions requiring immediate attention
2	Critical	Condition that should be addressed to prevent an interruption of service
3	Error	Error conditions that do not render the system unusable
4	Warning	Specific operations failed to complete successfully
5	Notifications	Non-error notifications that alert an administrator about state changes within a system
6	Informational	Detailed dinformation about the normal operation of a system
7	Debugging	Highly detailed information used for troubleshooting

Security

Library injections

Similar to DLL files on Windows systems, .so ("shared object") library files on Linux allow code to be shared by various processes. They are vulnerable to injection attacks. One file in particular, linux-vdso.so.1, finds and locates other shared libraries and is mapped by the kernel into the address space of every process. This library-loading mechanism can be exploited through the use of the environment variable LD_PRELOAD, which is considered the most convenient way to load a shared library in a process at startup. If defined, this variable is read by the system and the library is loaded immediately after linux-vdso.so.1 into every process that is run. ^

This attack can be detected using the osquery tool. This tool represents the system as a relational database which can then be queried, in particular against the process_envs table.

Linux commands

Applications

git imagemagick mongod GNOME gsettings gconf-editor KDE kquitapp krunner kstart SMB smbclient smbpasswd smbstatus

imagemagick

identify mogrify

imagemagick identify

Option	Effect
-format {string}	display formatted image characteristics; {string} is formatted string using %[key] escape sequences %w current width in pixels %h current height in pixels

imagemagick mogrify

Option	Effect
-write $FILENAME	save to filename
-resize $Xx$Y	resize image to $X pixels by $Y pixels
-crop $SIZE$OFFSET
-gravity $TYPE	set current gravity suggestion for various other options possible values NorthWest, North, NorthEast, West, Center, East, SouthWest, South, or SouthEast

Argument patterns --- | --- {geometry} | {size}{offset} {size} | {scale}% height and weight are both scaled by a specified percentage
{width}x{height} maximum values of height and width
{width}x{height}^ minimum values of height and width
{offset} | also affected by -gravity setting
+0+0 top-left corner gravity |

Resize images

magick mogrify -resize 1920x1200 -write mars-bg.jpg pia22511.jpg
magick identify -format "%w x %h" pia22511.jpg

Save the output of a command as an image (convert is from the ImageMagick software suite) ^ref

cmd | convert label:@- image.png

View image metadata (identify is from the ImageMagick software suite) ^{ostechnix.com}

identify image.png # => dimensions, color depth, color profile
identify -verbose image.png

krunner

Single-line application launcher similar to the Run command on Windows.

kquitapp

Allows you to quit a dbus enabled application. Two options:

Specify service to be stopped

kquitapp --service

Specify path to dbus interface

kquitapp --path

kstart

Restarting KDE Plasma 4 ^ref

killall plasma-desktop
kstart plasma-desktop

Restarting KDE Plasma 5 ^ref

killall plasmashell
kstart plasmashell

kquitapp5 plasmashell
kstart plasmashell

lowriter

lowriter is a command-line utility installed with LibreOffice Writer. ^vitux.com

Convert a single file to PDF

lowriter --convert-to pdf filename.doc

Convert a batch of files using globbing

lowriter --convert-to pdf *.docx

mongod

Run MongoDB service in the background on port 80

mongod --dbpath $HOME/db --port 80 --fork --logpath /var/tmp/mongodb