grog reads the input (file names or standard input) and guesses which
of the groff(1) options are needed to perform the input with the
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
character -) are interpreted as groff options or option clusters with
or without argument. No space is allowed between options and their
argument. 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
filespec 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
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
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
package. 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: grog.pl is the Perl version, while grog.sh is a shell
script using awk(1). During the run of make(1), it is determined
whether the system contains a suitable version of perl(1). If so,
grog.pl is transformed into grog; otherwise grog.sh is used instead.
groff -me meintro.me
So grog recognized that the file meintro.me is written with the -me
* On the other hand,
groff -p -t -e -ms pic.ms
Besides determining the macro package -ms, grog recognized that the
file pic.ms 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
grog meintro.me pic.ms
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 meintro.me pic.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.
This page is part of the groff (GNU troff) project. Information
about the project can be found at
⟨http://www.gnu.org/software/groff/⟩. If you have a bug report for
this manual page, see ⟨http://www.gnu.org/software/groff/⟩. This
page was obtained from the tarball groff-1.22.3.tar.gz fetched from
⟨ftp://ftp.gnu.org/gnu/groff/⟩ on 2016-10-04. If you discover any
rendering problems in this HTML version of the page, or you believe
there is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
Groff Version 1.22.3 4 November 2014 GROG(1)