hxindex - insert an index into an HTML document
hxindex [ -t ] [ -x ] [ -n ] [ -f ] [ -c classes ] [ -b base ] [ -i
indexdb ] [--] [ file-or-URL ]
The hxindex looks for terms to be indexed in a document, collects them,
turns them into target anchors and creates a sorted index as an HTML
list, which is inserted at the place of a placeholder in the document.
The resulting document is written to standard output.
The index is inserted at the place of a comment of the form
or between two comments of the form
In the latter case, all existing content between the two comments is
Index terms are either elements of type <dfn> or elements with a class
attribute of "index". (For backward compatibility, also class
attributes "index-inst" and "index-def" are recognized.) <dfn> elements
(and class "index-def") are considered more important than elements
with class "index" and will appear in bold in the generated index.
The option -c adds additional classes, that are aliases for "index".
By default, the contents of the element are taken as the index term.
Here are two examples of occurrences of the index term "shoe":
A <dfn>shoe</dfn> is a piece of clothing that...
completed by a leather <span class="index">shoe</span>...
If the term to be indexed is not equal to the contents of the element,
the title attribute can be used to give the correct term:
... <dfn title="shoe">Shoes</dfn> are pieces of clothing that...
... with two leather <span class="index" title="shoe">shoes</span>...
The title attribute must also be used when the index term is a subterm
of another. Subterms appear indented in the index, under their head
term. To define a subterm, use a title attribute with two exclamation
marks ("!!") between the term and the subterm, like this:
<dfn title="shoe!!invention of">...</dfn>
<em class="index" title="shoe!!protective!!steel nosed">...</em>
As the last example above shows, there can be multiple levels of sub-
The title attribute also allows multiple index terms to be associated
with a single occurrence. The multiple terms are separated with a
vertical bar ("|"). Compare the following examples with the ones above:
<dfn title="shoe!!invention of|inventions!!shoe">...</dfn>
These two elements both insert two terms into the index. Note that the
second example above combines subterms and multiple terms.
It is possible to run index on a file that already has an index. The
old target anchors and the old index will be removed before being re-
The following options are supported:
-t By default, hxindex adds an ID attribute to the element that
contains the occurrence of a term and also inserts an <a>
element inside it with a name attribute equal to the ID. This
is to allow old browsers that ignore ID attributes, such as
Netscape 4, to find the target as well. The -t option
suppresses the <a> element.
-x This option turns on XML syntax conventions: empty elements
will end in /> instead of > as in HTML. -x implies -t.
hxindex can read an initial index from a file and write the
merged collection of index terms back to that file. This
allows an index to span several documents. The -i option is
used to give the name of the file that contains the index.
-b base This option is useful in combination with -i to give the base
URL reference of the document. By default, hxindex will store
links to occurrences in the indexdb file in the form #anchor,
but when -b is given, the links will look like base#anchor
Normal index terms are recognized because they have a class
of "index". The -c option adds additional, comma-separated
class names that will be considered aliases for "index".
E.g., -c instance will make sure that <span
class="instance">term</span> is recognized as a term for the
-n By default, the index consists of links with "#" as the
anchor text. Option -n causes the link text to consist of
the section numbers of the sections in which the terms occur,
falling back to "#" only if no section number could be found.
Section numbers are found by looking for the nearest
preceding start tag with a class of "secno" or "no-num". In
the case of "secno", the contents of that element are taken
as the section number. In the case of "no-num" the section is
assumed to have no number and hxindex will print a "#"
instead. These classes are also used by hxnum(1), so it is
useful to run hxindex after hxnum, e.g.,
hxnum myfile.html | hxindex -n >mynewfile.html
-f Remove title attributes that were used for the index as well
as the comments that delimit the inserted index. This avoids
that browsers display these attributes. Note that hxindex
cannot be run again on its own output if this option is used.
(Mnemonic: "freeze" or "final".)
The following operand is supported:
The name of an HTML or XML file or the URL of one. If absent,
or if the file is "-", standard input is read instead.
The input is assumed to be in UTF-8, but the current locale is used to
determine the sorting order of the index terms. I.e., hxindex looks at
the LANG, LC_ALL and/or LC_COLLATE environment variables. See
The following exit values are returned:
0 Successful completion.
>0 An error occurred in parsing the HTML file.
asc2xml(1), hxnormalize(1), hxnum(1), hxprune(1), hxtoc(1), hxunent(1),
xml2asc(1), locale(1), UTF-8 (RFC 2279)
Assumes UTF-8 as input. Doesn’t expand character entities (apart from
the standard ones: "&", "<", ">" and """). Instead, pipe
the input through hxunent(1) and, if needed, asc2xml(1) to convert it