Display non-printing characters (see the -v option), and display a dollar sign ($) at the end of each line.
-n
Number the output lines, starting at 1.
-s
Squeeze multiple adjacent empty lines, causing the output to be single spaced.
-t
Display non-printing characters (see the -v option), and display tab characters as ^I.
-u
Disable output buffering.
-v
Display non-printing characters so they are visible. Control characters print as ^X for control-X; the delete character (octal 0177) prints as ^?. Non- ASCII characters (with the high bit set) are printed as M- (for meta) followed by the character for the low 7 bits.