grog(1) — Linux manual page

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grog(1)                    General Commands Manual                   grog(1)

Name         top

       grog - guess options for a following groff command

Synopsis         top

       grog [-C] [-T device] [--run] [--warnings] [--ligatures] [groff-
            option ...] [--] [filespec ...]

       grog -h
       grog --help

       grog -v
       grog --version

Description         top

       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
       groff program.  A suitable device is now always written as -Tdevice
       including the groff default as -T ps.

       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

Options         top

       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.

Details         top

       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, -p, -R, -s, -t (preprocessors);
       and -man, -mdoc, -mdoc-old, -me, -mm, -mom, and -ms (macro packages).

       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
       -marg options.

       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.

Example         top

       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.

Authors         top

       grog was originally written by James Clark.  The current Perl
       implementation was written by Bernd Warken ⟨groff-bernd.warken-72@⟩ with contributions from Ralph Corderoy, and is maintained by
       Werner Lemberg ⟨⟩.

See Also         top


COLOPHON         top

       This page is part of the groff (GNU troff) project.  Information
       about the project can be found at 
       ⟨⟩.  If you have a bug report for
       this manual page, see ⟨⟩.  This
       page was obtained from the project's upstream Git repository
       ⟨⟩ on 2020-07-14.  (At that
       time, the date of the most recent commit that was found in the repos‐
       itory was 2020-07-12.)  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
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       of the original manual page), send a mail to

groff            16 May 2020                         grog(1)

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