grohtml(1) General Commands Manual grohtml(1)
Name
grohtml, post-grohtml, pre-grohtml - groff output driver for HTML
Synopsis
pre-grohtml [-epV] [-a anti-aliasing-text-bits] [-D image-directory] [-F font-directory] [-g anti-aliasing-graphic-bits]
[-i resolution] [-I image-stem] [-o image-vertical-offset] [-x html-dialect] troff-command troff-argument ...
pre-grohtml --help
pre-grohtml -v
pre-grohtml --version
post-grohtml [-bCGhlnrVy] [-F font-directory] [-j output-stem] [-s base-point-size] [-S heading-level] [-x html-dialect]
[file ...]
post-grohtml --help
post-grohtml -v
post-grohtml --version
Description
The GNU roff system's HTML support consists of a preprocessor, pre-grohtml, and an output driver, post-grohtml; together,
they translate roff(7) documents to HTML. Because a preprocessor is (uniquely) required for this output driver, users
should invoke grohtml via the groff(1) command with the -Thtml or -Txhtml options. (In this installation, ps is the de‐
fault output device.) Use groff's -P option to pass any options shown above to grohtml. If no operands are given, or if
file is “-”, 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 troff(1) to HTML.
grohtml writes output encoded in UTF-8 and has built-in HTML entities for all non-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 (bold-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 bold-italic
CR Courier roman
CI Courier italic
CB Courier bold
CBI Courier bold-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
groff_font(5).
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 anti-aliasing-text-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 “CreationDate:” HTML comment.
-D image-directory
Instruct grohtml to place all image files into directory image-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 font-directory
Prepend directory font-directory/devname to the search path for font and device description files; name is the name
of the device, usually html.
-g anti-aliasing-graphic-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 ex‐
ploit antialiasing. A value of 0 stops grohtml from issuing antialiasing commands to gs.
-G Suppress output of “Creator:” 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 image-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 output-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 output-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 “?” on older versions of some browsers.
This feature is automatically enabled if a heading contains an image.
-o image-vertical-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 base-type-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 “big” element, and conversely when a decrease
of two points is seen, a “small” element is emitted.
-S heading-level
When splitting HTML output (see option -j above), split at each nested heading level defined by heading-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 html-dialect
Select HTML dialect. Currently, html-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 right-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
troff(1) and groff_font(5).
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 human-readable form using gmtime(3) and asctime(3), and recorded in an HTML
comment.
TZ The time zone to use when converting the current time to human-readable form; see tzset(3). If SOURCE_DATE_EPOCH
is used, it is always converted to human-readable form using UTC.
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 groff(1) 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.
See also
groff(1), troff(1), groff_font(5)
groff 1.23.0 31 March 2024 grohtml(1)