Please follow and complete the free online Command Line Crash Course tutorial. This is a great, quick tutorial. Each "chapter" focuses on a command. Type the commands you see in the Do This section, and read the You Learned This section. Move on to the next chapter. You should be able to go through these in a couple of hours.
Make a cheat sheet for yourself: a list of commands and what they do, focused on things that are new, interesting, or otherwise worth remembering.
Created MS-Word document with cheat sheet of all commands as well as a shorter version for less often used commands i might need to reference more often
What does ls do? What do ls -a, ls -l, and ls -lh do? What combinations of those flags are meaningful?
ls -- list contents of the current working directory (folders & files)
ls -a -- list all contents of current working directory (including hidden files)
ls -l -- list contents of current working directory with details (size, modified date, owner of files & permissions)
ls -lh -- list contents of current working directory with details in "human readable" format (file sizes not in byte sizes, but using KB, MB, GB notations)
What does xargs do? Give an example of how to use it.
xargs is to execute arguments for an input command.
Say in the case of using echo to print numbers, you want to print every 5 numbers in a sequence on a separate line.
Without using xargs, you might send:
echo {1..5}
echo {6..10}
echo {11..15}
echo {16..20}
Using xargs, you could issue one line to handle this:
echo {1..20} | xargs -n 5