ubuntu20.04常用命令有以下这些：
//The dpkg :
----dpkg -i<====> install
----dpkg -LShow info about this APP
----dpkg -rRemove
----dpkg --list Show all installed APPs\
//The apt :
----apt-get installinstall an app from sources.list
----apt update update the info about sources.list
----apt upgrade update the Apps
----apt-get --purge remove---->remove an app which named 'name'
----apt --fix-broken install deal with the broken
----apt -f install -y same with that
----apt-get removeremove but keep settings and files
//The Files:
----ls show the list of files
----cdjump to this file whose name is 'file's name'
----cd -L jump back to 'home'
----cp file's_name_1 /way.../end of the way copy file_1 to way_2
//The 'grub->':
----ls
----set root = (hdx,y)
//File_Way:
----sources.list -------> /etc/apt/sources.list
----Fonts -------> /usr/share/fonts