# ls | wc -l

 or

# echo * | wc -w


Echo is a built in command in Linux. 

wc - word count

-l - Count the lines

-w count the words

 When using echo * the result comes out as a single line with file names, so we need to use the -w option of wc.

When using ls the result comes out as a series of lines, one line per file, so we need to use the -l.

This makes some assumptions about the default configuration of ls.