SHELL

wc bash

 wc(1) - print newline, word, and byte counts for each file

Print  newline, word, and byte counts for each FILE, 
and a total line if more than one FILE is specified.
With no FILE, or when FILE is -, read standard input.  
A word is a non-zero-length sequence of characters
delimited  by  white  space.  The options below may be 
used to select which counts are printed, always in the 
following order: newline, word, character, byte, maximum 
line length.

-l, --lines
       print the newline counts

bash "wc -l"

wc file.txt
10		20		500 	file.txt
lines	words	bytes	file_name
wc -l file.txt # Outputs only lines (-l)
wc -w file.txt # Outputs only words (-w)
wc -c file.txt # Outputs only bytes (-c).