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grohtml

Section: User Commands (1)
Updated: 2 July 2023
Index Return to Main Contents

Name

grohtml, post-grohtml, pre-grohtml - groff output driver for HTML
.nr d-fallback 1
.nr d-fallback 1

Synopsis

[-epV] [-a ant-aliasin-tex-bits] [-D imag-directory] [-F fon-directory] [-g ant-aliasin-graphi-bits] [-i resolution] [-I imag-stem] [-o imag-vertica-offset] [-x htm-dialect] trof-command trof-argument ... --help -v --version [-bCGhlnrVy] [-F fon-directory] [-j outpu-stem] [-s bas-poin-size] [-S headin-level] [-x htm-dialect] [file~...] --help -v --version

Description

The GNU roff system's HTML support consists of a preprocessor, pre-grohtml, and an output driver, post-grohtml; together, they translate documents to HTML. Because a preprocessor is (uniquely) required for this output driver, users should invoke grohtml via the command with the -Thtml or -Txhtml options. (In this installation, ps is the default output device.) Use groff's -P option to pass any options shown above to grohtml. If no operands are given, or if file is [lq]-[rq], grohtml reads the standard input stream. Output is written to the standard output stream. grohtml invokes groff twice. In the first pass, the preprocessor pre-grohtml renders pictures, equations, and tables as images in PostScript format using the ps output device. In the second pass, the output driver post-grohtml translates the output of to HTML. grohtml writes output encoded in UT-8 and has buil-in HTML entities for all no-composite Unicode characters. In spite of this, groff may issue warnings about unknown special characters if they can't be found during the first pass. Such warnings can be safely ignored unless the special characters appear inside a table or equation.

Typefaces

grohtml supports the standard four styles: R (roman), I (italic), B (bold), and BI (BI]bol-italic]). Fonts are grouped into families T and C having members in each style.

TR: Times roman TI Times italic TB Times bold TBI Times bol-italic CR Courier roman CI Courier italic CB Courier bold CBI Courier bol-italic

A special font, S, is also provided to accommodate roff documents that expect it to always be available.

Font description files

The font description files used with grohtml expose the same glyph repertoire in their charset sections. See

Dependencies

pre-grohtml generates an image whenever an eqn equation, tbl table, or pic picture is encountered in the input. grohtml therefore may run several commands as part of its operation. These include the Netpbm tools pnmcrop, pnmcut, and pnmtopng; Ghostscript (gs); and the PSUtils tool psselect.

Options

--help displays a usage message, while -v and --version show version information; all exit afterward.

-a~ant-aliasin-tex-bits: Number of bits of antialiasing information to be used by text when generating PNG images. The default is~4 but 0, 1, and 2 are also valid. Your system's version of gs must support the -dTextAlphaBits option in order to exploit antialiasing. A value of~0 stops grohtml from issuing antialiasing commands to gs.
-b: Initialize the background color to white.
-C: Suppress output of [lq]CreationDate:[rq] HTML comment.
-D~imag-directory: Instruct grohtml to place all image files into directory imag-directory.
-e: Direct eqn to produce MathML.
: This option should not be manually specified; it is synthesized by groff depending on whether it was given the -Thtml or -Txhtml option.
-F~fon-directory: Prepend directory fon-directory/devname to the search path for font and device description files; name is the name of the device, usually html.
-g~ant-aliasin-graphi-bits: Number of bits of antialiasing information to be used by graphics when generating PNG images. The default is~4 but 0, 1, and 2 are also valid. Your system's version of gs must support the -dGraphicAlphaBits option in order to exploit antialiasing. A value of~0 stops grohtml from issuing antialiasing commands to gs.
-G: Suppress output of [lq]Creator:[rq] HTML comment.
-h: Generate section headings by using HTML B elements and increasing the font size, rather than HTML H elements.
-i~resolution: Set the image resolution in pixels per inch; the default is~100.
-I~imag-stem: Determine the image file name stem. If omitted, grohtml uses grohtml-XXXXX (where XXXXX is the process ID). A dash is appended to the stem to separate it from the following image number.
-j~outpu-stem: Instruct grohtml to split the HTML output into multiple files. Output is written to a new file at each section heading (but see option -S below) named outpu-stem-n.html.
-l: Turn off the production of automatic section links at the top of the document.
-n: Generate simple heading anchors whenever a section/number heading is found. Without the option the anchor value is the textual heading. This can cause problems when a heading contains a [lq]?[rq] on older versions of some browsers. This feature is automatically enabled if a heading contains an image.
-o~imag-vertica-offset: Specify the vertical offset of images in points.
-p: Display page rendering progress to the standard error stream. grohtml displays a page number only when an image is required.
-r: Turn off the automatic header and footer line (HTML rule).
-s~bas-typ-size: Set the document's base type size in points. When this size is used in the source, it corresponds to the HTML base type size. Every increase of two points in the source will produce a [lq]big[rq] element, and conversely when a decrease of two points is seen, a [lq]small[rq] element is emitted.
-S~headin-level: When splitting HTML output (see option -j above), split at each nested heading level defined by headin-level, or higher). The default is 1.
-V: Create an XHTML or HTML validator button at the bottom of each page of the document.
-x~htm-dialect: Select HTML dialect. Currently, htm-dialect should be either the digit~4 or the letter~x, which indicates whether grohtml should generate HTML~4 or XHTML, respectively.
: This option should not be manually specified; it is synthesized by groff depending on whether it was given the -Thtml or -Txhtml option.
-y: Produce a righ-aligned groff signature at the end of the document (only if -V is also specified).

Environment

GROFF_FONT_PATH: lists directories in which to search for devhtml, grohtml's directory of device and font description files. See and
SOURCE_DATE_EPOCH: A timestamp (expressed as seconds since the Unix epoch) to use as the output creation timestamp in place of the current time. The time is converted to huma-readable form using and recorded in an HTML comment.
TZ: The time zone to use when converting the current time (or value of SOURCE_DATE_EPOCH) to huma-readable form; see

Files

/usr/:share/:groff/:1.23.0/:font/:devhtml/:DESC: describes the html output device.
/usr/:share/:groff/:1.23.0/:font/:devhtml/F: describes the font known as~F on device html.
/usr/:share/:groff/:1.23.0/:tmac/:html:.tmac: defines font mappings, special characters, and colors for use with the html output device. It is automatically loaded by troffrc when either of the html or xhtml output devices is selected.
/usr/:share/:groff/:1.23.0/:tmac/:html-end:.tmac: finalizes setup of the html output device. It is automatically loaded by troffrc-end when either of the html or xhtml output devices is selected. grohtml uses temporary files. See for details about where such files are created.

Bugs

grohtml is still beta code.

grohtml does not truly support hyphenation, but you can fool it into hyphenating long input lines, which can appear in HTML output with a hyphenated word followed by a space but no line break.