Other Essentials

sudo, pipes, redirects, and man pages — the connective tissue that makes every other command more powerful.

sudo — borrowing admin rights #

sudo apt update
# run this command with administrative privileges

The pipe: | #

This might be the single most powerful idea in the entire shell: the output of one command becomes the input of the next.

ps aux | grep nginx

Redirects: > and >> #

echo "Hello Linux" > message.txt     # overwrites the file
echo "Second message" > message.txt   # replaces previous content entirely
echo "First line" > notes.txt
echo "Second line" >> notes.txt       # >> appends instead

Finding your own way: man and history #

You are not expected to memorize every flag of every command. man is how you look it up:

man ls
man chmod
man ssh          # press 'q' to exit

history shows what you’ve already run — useful both for reference and for rerunning something without retyping it:

history
!102             # re-run command number 102 from history
Ctrl + R         # search history interactively

And exit closes the current shell — or, if you’re connected over SSH, disconnects you from the remote machine.