nl [OPTION]... [FILE]...
Number lines of files
STYLE
is one of:
a
number all linest
number only nonempty linesn
number no linespBRE
number only lines that contain a match for the basic regular expression,BRE
FORMAT
is one of:
ln
left justified, no leading zerosrn
right justified, no leading zerosrz
right justified, leading zeros