Wiki
Command Tutorial (long-term accumulation)
About 1 min read
1.Most commands
https://www.runoob.com/linux/linux-tutorial.html
2.Package management tool command
Common ones include apt, dnf, yum, pacman, pkcon, and so on.
3.KDE Dolphin Open as root
kde5
pkexec env DISPLAY=$DISPLAY XAUTHORITY=$XAUTHORITY KDE_SESSION_VERSION=5 KDE_FULL_SESSION=true dolphin
kde6
pkexec env DISPLAY=$DISPLAY XAUTHORITY=$XAUTHORITY KDE_SESSION_VERSION=6 KDE_FULL_SESSION=true dolphin
kde6.3.3 and above

Direct graphical representation is sufficient.