You can do more use 'echo'.

here are some folders and files in current directory:
php /python ruby /html foo.txt bar.html index.html

echo p*

will lists php and /python

echo *.html

lists bar.html and index.html

echo ~

display current user directory

echo $((2+3))

echo can make calculation

echo begain-{1,2,3}-end

begain-1-end begain-2-end begain-3-end

echo NO.{1..3}

NO.1 NO.2 NO.3

echo $USER

current username