grog(1) General Commands Manual grog(1)
grog - “groff guess”—infer the groff command a document requires
grog [--run] [--ligatures] [groff-option ...] [--] [file ...] grog -h grog --help grog -v grog --version
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 generated command is written to the standard error stream and then executed.
-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 generated groff command. These are supported only by the pdf output driver. --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.
grog reads all file operands in their entirety, 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 command without change. Choices of groff options include -C to enable compatibility mode and -T to specify an output device other than the default. 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 arguments 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, and no-break control characters. grog does not parse roff input line continuation or control structures (brace escape sequences and the “if”, “ie”, and “el” requests) 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 implementors as insufficiently common to cause many inference problems; further, preprocessors are typically even stricter when matching the macro calls they use to bracket the regions of an input file they textually replace. pic, for example, requires PS and PE calls to immediately follow the default control character at the beginning of a line, with no intervening spaces or tabs. 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 only necessary 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 preprocessor options, then -s is likely necessary. $ printf ".TS\nl.\nThis is my table.\n.TE\n" > 3.roff $ printf ".so 3.roff\n" > 2.roff $ printf ".so 2.roff\n" > 1.roff $ grog 1.roff groff 1.roff $ soelim 1.roff | grog groff -t - 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 1.roff
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. Inferring no preprocessors or macro packages is not an error condition; a valid roff document need not use either, and even plain text is valid input, if one is mindful of the syntax of the control and escape characters.
Running grog meintro.me at the command line results in groff -me meintro.me because grog recognizes that the file meintro.me is written using macros from the me package. The command grog pic.ms outputs groff -t -e -p -ms 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. The command grog -ksS -Tdvi grnexmpl.g contains several groff options that are passed through without interference from grog. These are the option cluster -ksS and the typesetter option -T with argument dvi. The output is groff -ksS -T dvi grnexmpl.g so no additional option was added by grog. As no -m option was inferred by grog, this file does not use a macro package.
grog was originally written by James Clark. The current Perl implementation was written by Bernd Warken ⟨groff-bernd .email@example.com⟩ with contributions from Ralph Corderoy.
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 project's upstream Git repository ⟨https://git.savannah.gnu.org/git/groff.git⟩ on 2021-08-27. (At that time, the date of the most recent commit that was found in the repository was 2021-08-23.) 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 firstname.lastname@example.org groff 1.23.0.rc1.654-4e1db-dir1t9yAugust 2021 grog(1)
Pages that refer to this page: gperl(1), gpinyin(1), groff(1), groffer(1), roff(7)