Using ! and ctrl-R (goes back through your history to get previous commands)
There are two easy ways to retrieve past commands from your history (in addition to using the up/down arrow keys):
!character: if you type an exclamation point (also known as bang) followed by a character or a string and then enter, you will run the last command that starts with that character or string. E.g.,
$ ls -a
. .. hello hello.c hello.c~ innerFolder readme.txt samples
$ cd ..
$ !l
ls -a
. assign0 assign2 .do_not_look.txt file2.txt
.. assign1 assign3 file1.txt .this_is_hidden.txt
$
Typing !l runs ls -a again, because the previous command that started
with l was ls -a.
Ctrl-R: If you hold down the control key, and then type "r", you can then start typing characters and the line will start being populated with the last command that starts with the characters you have typed. This is easier to see in the Video and you should try it yourself.