grotty translates the output of GNU troff into a form suitable for typewriter-like devices. Normally grotty should be invoked by using the groff command with a -Tascii, -Tlatin1, -Tkoi8-r or -Tutf8 option on ASCII based systems, and with -Tcp1047 and -Tutf8 on EBCDIC based hosts. If no files are given, grotty will read the standard input. A filename of - will also cause grotty to read the standard input. Output is written to the standard output.
By default, grotty emits SGR escape sequences (from ISO 6429, also called ANSI color escapes) to change text attributes (bold, italic, colors). This makes it possible to have eight different [green]background and [red]foreground colors; additionally, bold and italic attributes can be used BI]at the same time] (by using the BI font).
The following colors are defined in tty.tmac: black, white, red, green, blue, yellow, magenta, cyan. Unknown colors are mapped to the default color (which is dependent on the settings of the terminal; in most cases, this is black for the foreground and white for the background).
Use the -c switch to revert to the old behaviour, printing a bold character c with the sequence c BACKSPACE c and an italic character c by the sequence _ BACKSPACE c. At the same time, color output is disabled. The same effect can be achieved by setting either the GROFF_NO_SGR environment variable or using the sgr X command (see below).
For SGR support, it is necessary to use the -R option of less(1) to disable the interpretation of grottys old output format. Consequently, all programs which use less as the pager program have to pass this option to it. For man(1) in particular, either add -R to the $PAGER environment variable, e.g.
PAGER= "/usr/bin/less -R"
or use the -P option of man to set the pager executable and its options, or modify the configuration file of man in a similar fashion.
grottys old output format can be displayed on a terminal by piping through ul(1). Pagers such as more(1) or less(1) are also able to display these sequences. Use either -B or -U when piping into less(1); use -b when piping into more(1). There is no need to filter the output through col(1) since grotty never outputs reverse line feeds.
The font description file may contain a command