Exercise 1
==========
find /usr -size +50M

Exercise 2
==========
du -sh /usr

Exercise 3
==========
ls /etc | sort -rf

Exercise 4
===========
Two ways of doing.

First way, in two steps:
  echo "hello world" > blah.txt
  echo "bye bye" >> blah.txt

Second way, in a single step
  echo -e 'hello world \nbye bye' > blah.txt

Note: \n is a special character ("newline").
The leading backslash is to tell the system that this
is a special characters.  

Exercise 5
===========
cal 3 2022

Exercise 6
==========
cal 3 2022 | colrm 1 3 | colrm 4 | grep [0-9]