grog Man page

GROG(1) General Commands Manual GROG(1)


grog — guess options for a following groff command


grog [-C] [–run] [–warnings] [–ligatures] [ groff-option ….] [–] [ filespec ….] grog -h | –help
grog -v | –version


grog reads the input (file names or standard input) and guesses which
of the groff options are needed to perform the input with the groff

The corresponding groff command is usually displayed in standard
output. With the option –run, the generated line is output
into standard error and the generated groff command is run on
the standard output.


The option -v or –version prints information on the version number.
Also -h or –help prints usage information. Both of these options
automatically end the grog program. Other options are thenignored, and
no groff command line is generated. The following 3 options are the
only grog options,

-C this option means enabling the groff compatibility mode, which
is also transfered to the generated groff command line.

this option forces to include the arguments -P-y -PU within the
generated groff command line.

–run with this option, the command line is output at standard error
and then run on the computer.

with this option, some more warnings are output to standard

All other specified short options (words starting with one minus char‐
acter -) are interpreted as groff options or option clusters with or
without argument. No space is allowed between options and their argu‐
ment. Except from the -marg options, all options will be passed on,
i.e. they are included unchanged in the command for the output without
effecting the work of grog.

A filespec argument can either be the name of an existing file or a
single minus – to mean standard input. If no filespec is specified
standard input is read automatically.

grog reads all filespec parameters as a whole. It tries to guess which
of the following groff options are required for running the input under
groff: -e, -g, -G, -j, -J, -p, -R, -s, -t. -man, -mdoc, -mdoc-old,
-me, -mm, -mom, and -ms.

The guessed groff command including those options and the found file‐
spec parameters is put on the standard output.

It is possible to specify arbitrary groff options on the command line.
These are passed on the output without change, except for the -marg

The groff program has trouble when the wrong -marg option or several of
these options are specified. In these cases, grog will print an error
message and exit with an error code. It is better to specify no -marg
option. Because such an option is only accepted and passed when grog
does not find any of these options or the same option is found.

If several different -marg options are found by grog an error message
is produced and the program is terminated with an error code. But the
output is written with the wrong options nevertheless.

Remember that it is not necessary to determine a macro package. A roff
file can also be written in the groff language without any macro pack‐
age. grog will produce an output without an -marg option.

As groff also works with pure text files without any roff requests,
grog cannot be used to identify a file to be a roff file.

The groffer(1) program heavily depends on a working grog.

The grog source contains two files written in different programming
languages: is the Perl version, while is a shell script
using awk. During the run of make, it is determined whether the
system contains a suitable version of perl. If so, is
transformed into grog; otherwise is used instead.

* Calling


results in

groff -me

So grog recognized that the file is written with the -me
macro package.

* On the other hand,



groff -p -t -e -ms

Besides determining the macro package -ms, grog recognized that the
file additionally needs -pte, the combination of -p for pic,
-t for tbl, and -e for eqn.

* If both of the former example files are combined by the command


an error message is sent to standard error because groff cannot work
with two different macro packages:

grog: error: there are several macro packages: -me -ms

Additionally the corresponding output with the wrong options is
printed to standard output:

groff -pte -me -ms

But the program is terminated with an error code.

* The call of

grog -ksS -Tdvi grnexmpl.g

contains several groff options that are just passed on the output
without any interface to grog. These are the option cluster -ksS
consisting of -k, -s, and -S; and the option -T with argument dvi.
The output is

groff -k -s -S -Tdvi grnexmpl.g

so no additional option was added by grog. As no option -marg was
found by grog this file does not use a macro package.


groff, groffer(1) troff, tbl, pic, chem(1), eqn,
refer(1), grn(1), grap(1), soelim
Man-pages of section 1 can be viewed with either
$ man name
for text mode or
$ groffer name
for graphical mode (default is PDF mode).

groff_me(7), groff_ms(7), groff_mm(7), groff_mom(7), groff_man(7)
Man-pages of section 7 can be viewed with either with
$ man 7 name
for text mode or
$ groffer 7 name
for graphical mode (default is PDF mode).

Copyright © 1989-2014 Free Software Foundation, Inc.

This file is part of grog, which is part of groff, a free software
project. You can redistribute it and/or modify it under the terms of
the GNU General Public License version 2 (GPL2) as published by the
Free Software Foundation.

groff is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

The text for GPL2 is available in the internet at GNU copyleft site

Written by James Clark.

Maintained by Werner Lemberg ⟨⟩.

Rewritten and put under GPL by Bernd Warken ⟨groff-⟩.

Groff Version 1.22.3 28 January 2016 GROG(1)