scp (if the private key is id_rsa, [-i] can be removed)
scp -i key -P port localfile user@ip:path

back to the beginning of line
Ctrl + a

go to the end of line
Ctrl + e

cut character from current position to the beginning
Ctrl + u

cut character from current position to the end
Ctrl + k

set timezone
timedatectl set-timezone Asia/Hong_Kong

run in background
nohup command > logfile 2>&1 &

use ImageMagick to crop an image file(WIDTHxHEIGHT+X+Y)
convert input.jpg -crop 100x100+12+34 output.jpg

use ImageMagick to concatenate different size image files
horizontally
convert +append image1.jpg image2.jpg image3.jpg output.jpg
vertically
convert -append image1.jpg image2.jpg image3.jpg output.jpg