GNU nroff emulates the traditional Unix nroff command using groff(1). nroff generates output via grotty(1), groff's TTY output device, which needs to know the character encoding scheme used by the terminal. Consequently, acceptable arguments to the -T option are ascii, latin1, utf8, and cp1047; any others are ignored. If neither the GROFF_TYPESETTER environment variable nor the -T command-line option (which overrides the environment variable) specifies a (valid) device, nroff consults the locale to select an appropriate output device. It first tries the locale(1) program, then checks several locale-related environment variables; see "ENVIRONMENT", below. If all of the foregoing fail, -Tascii is implied.
Whitespace is not permitted between an option and its argument. The -h and -c options are equivalent to grotty's options -h (using tabs in the output) and -c (using the old output scheme instead of SGR escape sequences). The -d, -C, -i, -M, -m, -n, -o, -r, -w, and -W options have the effect described in troff(1). In addition, nroff ignores -e, -q, and -s (which are not implemented in troff). The options -p (pic), -t (tbl), -S (safer), and -U (unsafe) are passed to groff. -v and --version show version information, while --help displays a usage message; all exit afterward.