Arch Linux

Kernel

Send SIGKILL to all process, forcing them to terminate immediately

Alt + Sys Rq + I

All hotkeys for Arch Linux

Kernel
Take control of keyboard back from X

Alt + Sys Rq + R

Kernel
Send SIGTERM to all processes, allowing them to terminate gracefully

Alt + Sys Rq + E

Kernel
Send SIGKILL to all process, forcing them to terminate immediately

Alt + Sys Rq + I

Kernel
Sync - Flush data to disk

Alt + Sys Rq + S

Kernel
Unmount - Unmound and remount all file systems read-only

Alt + Sys Rq + U

Kernel
Reboot

Alt + Sys Rq + B

Terminal: Virtual console
Reboots Computer (specified by the symlink /usr/lib/systemd/system/ctrl-alt-del.target)

Ctrl + Alt + Del

Terminal: Virtual console
(F2, F3, …) Switch to n-th virtual console

Alt + F1

Terminal: Virtual console
Switch to previous virtual console

Alt +

Terminal: Virtual console
Switch to next virtual console

Alt +

Terminal: Virtual console
When Scroll Lock is activated, input/output is locked

Scroll Lock

Terminal: Virtual console
Scroll console buffer up

Shift + Page Up

Terminal: Virtual console
Scroll console buffer down

Shift + Page Down

Terminal: Virtual console
Kills current task

Ctrl + C

Terminal: Virtual console
Inserts an EOF

Ctrl + D

Terminal: Virtual console
Pauses current task

Ctrl + Z

Terminal: Readline
Clear the screen

Ctrl + L

Terminal: Readline
Move cursor one character to the left

Ctrl + B

Terminal: Readline
Move cursor one character to the right

Ctrl + F

Terminal: Readline
Move cursor one word to the left

Alt + B

Terminal: Readline
Move cursor one word to the right

Alt + F

Terminal: Readline
Move cursor to start of the line

Ctrl + A

Terminal: Readline
Move cursor to end of the line

Ctrl + E

Terminal: Readline
Cut everything from line start to cursor

Ctrl + U

Terminal: Readline
Cut everything from the cursor to end of the line

Ctrl + K

Terminal: Readline
Cut the current word after the cursor

Alt + D

Terminal: Readline
Cut the current word before the cursor

Ctrl + W

Terminal: Readline
Paste the previous cut text

Ctrl + Y

Terminal: Readline
Paste the second latest cut text

Alt + Y

Terminal: Readline
Paste the first argument of the previous command

Alt + Ctrl + Y

Terminal: Readline
Paste the last argument of the previous command

Alt + ./_

Terminal: Readline
Move to the previous line

Ctrl + P

Terminal: Readline
Move to the next line

Ctrl + N

Terminal: Readline
Search

Ctrl + S

Terminal: Readline
Reverse search

Ctrl + R

Terminal: Readline
End search

Ctrl + J

Terminal: Readline
Abort search (restores original line)

Ctrl + G

Terminal: Readline
Restore all changes made to line

Alt + R

Terminal: Readline
Auto-complete a name

⭾ Tab

Terminal: Readline
List all possible completions

Alt + ?

Terminal: Readline
Insert all possible completions

Alt + *

X11 & Wayland
(F2, F3, …) Switch to n-th virtual console. If it doesn't work, try  Ctrl + Fn + Alt + F

Ctrl + Alt + F1

X11 & Wayland
Paste text from the PRIMARY buffer

↑   Shift + Insert

X11 & Wayland
Paste text from the PRIMARY buffer

Mouse right click

Similar combinations for other applications