To change to a directory that is up one level from the current working directory in the UNIX hierarchical directory tree structure, you can type .

No, the only way you can mute the notifications is to disable notification sounds in the settings, the settings of your phone of

Multitouch interface;

This is an opinion based question, someone on the internet can’t answer it for you. it’s not like a math problem that has the same solution, this comes from your brain and what you think.