Even with -ba (which I could never remember), nl does too much magic: $ printf 'foo\n\:\nbar\n' | cat -n 1 foo 2 \: 3 bar $ printf

Even with -ba (which I could never remember), nl does too much magic: $ printf 'foo\n\:\nbar\n' | cat -n 1 foo 2 \: 3 bar $ printf 'foo\n\:\nbar\n' | nl -ba 1 foo bar