groff (1.23.0)
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Versionsgrog(1) General Commands Manual grog(1)
Name
grog - “groff guess”—infer the groff command a document requires
Synopsis
grog [--run] [--ligatures] [groff-option ...] [--] [file ...]
grog -h
grog --help
grog -v
grog --version
Description
grog reads its input and guesses which groff(1) options are needed to render it. If no operands are given, or if
file is “-”, grog reads the standard input stream. The corresponding groff command is normally written to the
standard output stream. With the option --run, the inferred command is written to the standard error stream and
then executed.
Options
-h and --help display a usage message, whereas -v and --version display version information; all exit afterward.
--ligatures
includes the arguments -P-y -PU in the inferred groff command. These are supported only by the pdf output
device.
--run writes the inferred command to the standard error stream and then executes it.
All other specified short options (that is, arguments beginning with a minus sign “-” followed by a letter) are
interpreted as groff options or option clusters with or without an option argument. Such options are included in
the constructed groff command line.
Details
grog reads each file operand, pattern-matching strings that are statistically likely to be characteristic of
roff(7) documents. It tries to guess which of the following groff options are required to correctly render the
input: -e, -g, -G, -j, -p, -R, -t (preprocessors); and -man, -mdoc, -mdoc-old, -me, -mm, -mom, and -ms (macro
packages). The inferred groff command including these options and any file parameters is written to the standard
output stream.
It is possible to specify arbitrary groff options on the command line. These are included in the inferred com‐
mand without change. Choices of groff options include -C to enable AT&T troff compatibility mode and -T to se‐
lect a non-default output device. If the input is not encoded in US-ASCII, ISO 8859-1, or IBM code page 1047,
specification of a groff option to run the preconv(1) preprocessor is advised; see the -D, -k, and -K options of
groff(1). For UTF-8 input, -k is a good choice.
groff may issue diagnostic messages when an inappropriate -m option, or multiple conflicting ones, are specified.
Consequently, it is best to specify no -m options to grog unless it cannot correctly infer all of the -m argu‐
ments a document requires. A roff document can also be written without recourse to any macro package. In such
cases, grog will infer a groff command without an -m option.
Limitations
grog presumes that the input does not change the escape, control, or no-break control characters. grog does not
parse roff input line continuation or control structures (brace escape sequences and the “if”, “ie”, and “el” re‐
quests) nor groff's “while”. Thus the input
.if \
t .NH 1
.if n .SH
Introduction
will conceal the use of the ms macros NH and SH from grog. Such constructions are regarded by grog's implemen‐
tors as insufficiently common to cause many inference problems. Preprocessors can be even stricter when matching
macro calls that bracket the regions of an input file they replace. pic, for example, requires PS, PE, and PF
calls to immediately follow the default control character at the beginning of a line.
Detection of the -s option (the soelim(1) preprocessor) is tricky; to correctly infer its necessity would require
grog to recursively open all files given as arguments to the .so request under the same conditions that soelim
itself does so; see its man page. Recall that soelim is necessary only if sourced files need to be preprocessed.
Therefore, as a workaround, you may want to run the input through soelim manually, piping it to grog, and compare
the output to running grog on the input directly. If the “soelim”ed input causes grog to infer additional pre‐
processor options, then -s is likely necessary.
$ printf ".TS\nl.\nI'm a table.\n.TE\n" > 3.roff
$ printf ".so 3.roff\n" > 2.roff
$ printf ".XP\n.so 2.roff\n" > 1.roff
$ grog 1.roff
groff -ms 1.roff
$ soelim 1.roff | grog
groff -t -ms -
In the foregoing example, we see that this procedure enabled grog to detect tbl(1) macros, so we would add -s as
well as the detected -t option to a revised grog or groff command.
$ grog -st 1.roff
groff -st -ms 1.roff
Exit status
grog exits with error status 1 if a macro package appears to be in use by the input document, but grog was unable
to infer which one, or 2 if there were problems handling an option or operand. It otherwise exits with status 0.
(If the --run option is specified, groff's exit status is discarded.) Inferring no preprocessors or macro pack‐
ages is not an error condition; a valid roff document need not use either. Even plain text is valid input, if
one is mindful of the syntax of the control and escape characters.
Examples
Running
grog /BuggyBox/groff/1.23.0/any/share/doc/groff-1.23.0/meintro.me
at the command line results in
groff -me /BuggyBox/groff/1.23.0/any/share/doc/groff-1.23.0/meintro.me
because grog recognizes that the file meintro.me is written using macros from the me package. The command
grog /BuggyBox/groff/1.23.0/any/share/doc/groff-1.23.0/pic.ms
outputs
groff -e -p -t -ms /BuggyBox/groff/1.23.0/any/share/doc/groff-1.23.0/pic.ms
on the other hand. Besides discerning the ms macro package, grog recognizes that the file pic.ms additionally
needs the combination of -t for tbl, -e for eqn, and -p for pic.
Consider a file doc/grnexampl.me, which uses the grn preprocessor to include a gremlin(1) picture file in an me
document. Let's say we want to suppress color output, produce a DVI file, and get backtraces for any errors that
troff encounters. The command
grog -bc -Idoc -Tdvi doc/grnexmpl.me
is processed by grog into
groff -bc -Idoc -Tdvi -e -g -me doc/grnexmpl.me
where we can see that grog has inferred the me macro package along with the eqn and grn preprocessors. (The in‐
put file is located in /BuggyBox/groff/1.23.0/any/share/doc/groff-1.23.0 if you'd like to try this example your‐
self.)
Authors
grog was originally written in Bourne shell by James Clark. The current implementation in Perl was written by
Bernd Warken ⟨groff-bernd.warken-72@web.de⟩ and heavily revised by G. Branden Robinson ⟨g.branden.robinson@gmail
.com⟩.
See also
groff(1)
groff 1.23.0 2 July 2023 grog(1)
Name
grog - “groff guess”—infer the groff command a document requires
Synopsis
grog [--run] [--ligatures] [groff-option ...] [--] [file ...]
grog -h
grog --help
grog -v
grog --version
Description
grog reads its input and guesses which groff(1) options are needed to render it. If no operands are given, or if
file is “-”, grog reads the standard input stream. The corresponding groff command is normally written to the
standard output stream. With the option --run, the inferred command is written to the standard error stream and
then executed.
Options
-h and --help display a usage message, whereas -v and --version display version information; all exit afterward.
--ligatures
includes the arguments -P-y -PU in the inferred groff command. These are supported only by the pdf output
device.
--run writes the inferred command to the standard error stream and then executes it.
All other specified short options (that is, arguments beginning with a minus sign “-” followed by a letter) are
interpreted as groff options or option clusters with or without an option argument. Such options are included in
the constructed groff command line.
Details
grog reads each file operand, pattern-matching strings that are statistically likely to be characteristic of
roff(7) documents. It tries to guess which of the following groff options are required to correctly render the
input: -e, -g, -G, -j, -p, -R, -t (preprocessors); and -man, -mdoc, -mdoc-old, -me, -mm, -mom, and -ms (macro
packages). The inferred groff command including these options and any file parameters is written to the standard
output stream.
It is possible to specify arbitrary groff options on the command line. These are included in the inferred com‐
mand without change. Choices of groff options include -C to enable AT&T troff compatibility mode and -T to se‐
lect a non-default output device. If the input is not encoded in US-ASCII, ISO 8859-1, or IBM code page 1047,
specification of a groff option to run the preconv(1) preprocessor is advised; see the -D, -k, and -K options of
groff(1). For UTF-8 input, -k is a good choice.
groff may issue diagnostic messages when an inappropriate -m option, or multiple conflicting ones, are specified.
Consequently, it is best to specify no -m options to grog unless it cannot correctly infer all of the -m argu‐
ments a document requires. A roff document can also be written without recourse to any macro package. In such
cases, grog will infer a groff command without an -m option.
Limitations
grog presumes that the input does not change the escape, control, or no-break control characters. grog does not
parse roff input line continuation or control structures (brace escape sequences and the “if”, “ie”, and “el” re‐
quests) nor groff's “while”. Thus the input
.if \
t .NH 1
.if n .SH
Introduction
will conceal the use of the ms macros NH and SH from grog. Such constructions are regarded by grog's implemen‐
tors as insufficiently common to cause many inference problems. Preprocessors can be even stricter when matching
macro calls that bracket the regions of an input file they replace. pic, for example, requires PS, PE, and PF
calls to immediately follow the default control character at the beginning of a line.
Detection of the -s option (the soelim(1) preprocessor) is tricky; to correctly infer its necessity would require
grog to recursively open all files given as arguments to the .so request under the same conditions that soelim
itself does so; see its man page. Recall that soelim is necessary only if sourced files need to be preprocessed.
Therefore, as a workaround, you may want to run the input through soelim manually, piping it to grog, and compare
the output to running grog on the input directly. If the “soelim”ed input causes grog to infer additional pre‐
processor options, then -s is likely necessary.
$ printf ".TS\nl.\nI'm a table.\n.TE\n" > 3.roff
$ printf ".so 3.roff\n" > 2.roff
$ printf ".XP\n.so 2.roff\n" > 1.roff
$ grog 1.roff
groff -ms 1.roff
$ soelim 1.roff | grog
groff -t -ms -
In the foregoing example, we see that this procedure enabled grog to detect tbl(1) macros, so we would add -s as
well as the detected -t option to a revised grog or groff command.
$ grog -st 1.roff
groff -st -ms 1.roff
Exit status
grog exits with error status 1 if a macro package appears to be in use by the input document, but grog was unable
to infer which one, or 2 if there were problems handling an option or operand. It otherwise exits with status 0.
(If the --run option is specified, groff's exit status is discarded.) Inferring no preprocessors or macro pack‐
ages is not an error condition; a valid roff document need not use either. Even plain text is valid input, if
one is mindful of the syntax of the control and escape characters.
Examples
Running
grog /BuggyBox/groff/1.23.0/any/share/doc/groff-1.23.0/meintro.me
at the command line results in
groff -me /BuggyBox/groff/1.23.0/any/share/doc/groff-1.23.0/meintro.me
because grog recognizes that the file meintro.me is written using macros from the me package. The command
grog /BuggyBox/groff/1.23.0/any/share/doc/groff-1.23.0/pic.ms
outputs
groff -e -p -t -ms /BuggyBox/groff/1.23.0/any/share/doc/groff-1.23.0/pic.ms
on the other hand. Besides discerning the ms macro package, grog recognizes that the file pic.ms additionally
needs the combination of -t for tbl, -e for eqn, and -p for pic.
Consider a file doc/grnexampl.me, which uses the grn preprocessor to include a gremlin(1) picture file in an me
document. Let's say we want to suppress color output, produce a DVI file, and get backtraces for any errors that
troff encounters. The command
grog -bc -Idoc -Tdvi doc/grnexmpl.me
is processed by grog into
groff -bc -Idoc -Tdvi -e -g -me doc/grnexmpl.me
where we can see that grog has inferred the me macro package along with the eqn and grn preprocessors. (The in‐
put file is located in /BuggyBox/groff/1.23.0/any/share/doc/groff-1.23.0 if you'd like to try this example your‐
self.)
Authors
grog was originally written in Bourne shell by James Clark. The current implementation in Perl was written by
Bernd Warken ⟨groff-bernd.warken-72@web.de⟩ and heavily revised by G. Branden Robinson ⟨g.branden.robinson@gmail
.com⟩.
See also
groff(1)
groff 1.23.0 2 July 2023 grog(1)