Command Name	What You Must Implement
echo	Takes 1 argument and prints it.
pwd	Takes no arguments and prints the current path.
cd	Implement all these cases:
	1. cd takes no arguments and changes the current path to the path
	of your home directory.
	2. cd takes 1 argument which is “..” (e.g. cd ..) and changes the
	current directory to the previous directory.
	3. cd takes 1 argument which is either the full path or the
	relative (short) path and changes the current path to that path.
ls	Takes no arguments and lists the contents of the current directory
	sorted alphabetically.
ls -r	Takes no arguments and lists the contents of the current directory in
	reverse order.
mkdir	Takes 1 or more arguments and creates a directory for each argument.
	Each argument can be:
	• Directory name (in this case the new directory is created in
	the current directory)
	• Path (full/short) that ends with a directory name (in this case the
	new directory is created in the given path)
rmdir	Implement all these cases:
	1. rmdir takes 1 argument which is “*” (e.g. rmdir *) and removes all
	the empty directories in the current directory.
	• rmdir takes 1 argument which is either the full path or the relative
	(short) path and removes the given directory only if it is empty.
touch	Takes 1 argument which is either the full path or the relative (short) path
	that ends with a file name and creates this file.
cp	Takes 2 arguments, both are files and copies the first onto the second.
cp -r	Takes 2 arguments, both are directories (empty or not) and copies the first
	directory (with all its content) into the second one.
rm	Takes 1 argument which is a file name that exists in the current directory and
	removes this file.
cat	Takes 1 argument and prints the file’s content or takes 2 arguments and
	concatenates the content of the 2 files and prints it.
wc	Wc stands for “word count,” and as the name suggests, it is mainly
	used for counting purpose. By default, it displays four-columnar output.
	First column shows number of lines present in a file specified,
	second column shows number of words present in the file, third
	column shows number of characters present in file and fourth
	column itself is the file name which are given as argument
	Example:
	wc file.txt
	Output:
	9 79 483 file.txt
	Explanation:
	# 9 lines, 79 word, 483 character with spaces, file name
>	Format: command > FileName
	Redirects the output of the first command to be written to a file. If the
	file doesn’t exist, it will be created.
	If the file exists, its original content will be replaced.
	Example:
	echo Hello World > myfile.txt
	ls > file
>>	Like > but appends to the file if it exists.
history	Takes no parameters and displays an enumerated list with the commands you’ve
	used in the past
	Example:
	history
	Output:
	1 ls
	2 mkdir tutorial
	3 history