Black screen on start up. fixed by reboot [Solved]

Do I assume correctly you want to know what it means to use sudo? sudo is a command that allows the “normal” user to execute commands as super user (root) Lifewire: Tech News, Reviews, Help & How-Tos

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Details how to access OSMC via command line locally or via ssh can be found here: Accessing the command line - General - OSMC
Here is a cheatsheet for how to navigate in a linux shell: Cheatsheets and Tutorials for users new to Linux based operating systems