doclifter - Online in the Cloud

PROGRAM:

NAME

doclifter - translate troff requests into DocBook

SYNOPSIS

doclifter [-e encoding] [-h hintfile] [-q] [-x] [-v] [-w] [-V] [-D token=type] [-I path]
[-I path] file...

DESCRIPTION

doclifter translates documents written in troff macros to DocBook. Structural subsets of
the requests in man(7), mdoc(7), ms(7), me(7), mm(7), and troff(1) are supported.

The translation brings over all the structure of the original document at section,
subsection, and paragraph level. Command and C function synopses are translated into
DocBook markup, not just a verbatim display. Tables (TBL markup) are translated into
DocBook table markup. PIC diagrams are translated into SVG. Troff-level information that
might have structural implications is preserved in XML comments.

Where possible, font-change macros are translated into structural markup. doclifter
recognizes stereotyped patterns of markup and content (such as the use of italics in a
FILES section to mark filenames) and lifts them. A means to edit, add, and save semantic
hints about highlighting is supported.

Some cliches are recognized and lifted to structural markup even without highlighting.
Patterns recognized include such things as URLs, email addresses, man page references, and
C program listings.

The tag .in and .ti requests are passed through with complaints. They indicate
presentation-level markup that doclifter cannot translate into structure; the output will
require hand-fixing.

The tag .ta is passed through with a complaint unless the immediarely following by text
lines contains a tab, in which case the following span of lines containing tabs is lifted
to a table.

Under some circumstances, doclifter can even lift formatted manual pages and the text
output produced by lynx(1) from HTML. If it finds no macros in the input, but does find a
NAME section header, it tries to interpret the plain text as a manual page (skipping
boilerplate headers and footers generated by lynx(1)). Translations produced in this way
will be prone to miss structural features, but this fallback is good enough for simple man
pages.

doclifter does not do a perfect job, merely a surprisingly good one. Final polish should
be applied by a human being capable of recognizing patterns too subtle for a computer. But
doclifter will almost always produce translations that are good enough to be usable before
hand-hacking.

See the Troubleshooting section for discussion of how to solve document conversion
problems.

OPTIONS

If called without arguments doclifter acts as a filter, translating troff source input on
standard input to DocBook markup on standard output. If called with arguments, each
argument file is translated separately (but hints are retained, see below); the suffix
.xml is given to the translated output.

-h
Name a file to which information on semantic hints gathered during analysis should be
written.

-D
The -D allows you to post a hint. This may be useful, for example, if doclifter is
mis-parsing a synopsis because it doesn't recognize a token as a command. This hint is
merged after hints in the input source have been read.

-I
The -I option adds its argument to the include path used when docfilter searches for
inclusions. The include path is initially just the current directory.

-e
The -e allows you to set the encoding field to be emitted in the output XML. It
defaults to ISO-8859-1 (Latin-1).

-q
Normally, requests that doclifter could not interpret (usually because they're
presentation-level) are passed through to XML comments in the output. The -q option
suppresses this. It also suppresses listing of macros. Messages about requests that
are unrecognized or cannot be translated go to standard error whatever the state of
this option. This option is intended to reduce clutter when you believe you have a
clean lift of a document and want to lose the troff legacy.

-x
The -x option requests that doclifter generated DocBook version 5 compatible xml
content, rather than its default DocBook version 4.4 output. Inclusions and entities
may not be handled correctly with this switch enabled.

-v
The -v option makes doclifter noisier about what it's doing. This is mainly useful for
debugging.

-w
Enable strict portability checking. Multiple instances of -w increase the strictness.
See the section called “PORTABILITY CHECKING”.

-V
With this option, the program emits a version message and exits.

TRANSLATION RULES

Overall, you can expect that font changes will be turned into Emphasis macros with a Remap
attribute taken from the troff font name. The basic font names are R, I, B, U, CW, and SM.

Troff and macro-package special character escapes are mapped into ISO character entities.

When doclifter encounters a .so directive, it searches for the file. If it can get read
access to the file, and open it, and the file consists entirely of command lines and
comments, then it is included. If any of these conditions fails, an entity reference for
it is generated.

doclifter performs special parsing when it recognizes a display such as is generated by
.DS/.DE. It repeatedly tries to parse first a function synopsis, and then plain text off
what remains in the display. Thus, most inline C function prototypes will be lifted to
structured markup.

Some notes on specific translations:

Man Translation
doclifter does a good job on most man pages, It knows about the extended UR/UE/UN and URL
requests supported under Linux. If any .UR request is present, it will translate these but
not wrap URLs outide them with Ulink tags. It also knows about the extended .L (literal)
font markup from Bell Labs Version 8, and its friends.

The .TH macro is used to generate a RefMeta section. If present, the date/source/manual
arguments (see man(7)) are wrapped in RefMiscInfo tag pairs with those class attributes.
Note that doclifter does not change the date.

doclifter performs special parsing when it recognizes a synopsis section. It repeatedly
tries to parse first a function synopsis, then a command synopsis, and then plain text off
what remains in the section.

The following man macros are translated into emphasis tags with a remap attribute: .B, .I,
.L, .BI, .BR, .BL, .IB, .IR, .IL, .RB, .RI, .RL, .LB, .LI, .LR, .SB, .SM. Some stereotyped
patterns involving these macros are recognized and turned into semantic markup.

The following macros are translated into paragraph breaks: .LP, .PP, .P, .HP, and the
single-argument form of .IP.

The two-argument form of .IP is translated either as a VariableList (usually) or
ItemizedList (if the tag is the troff bullet or square character).

The following macros are translated semantically: .SH,.SS, .TP, .UR, .UE, .UN, .IX. A .UN
call just before .SH or .SS sets the ID for the new section.

The \*R, \*(Tm, \*(lq, and \*(rq symbols are translated.

The following (purely presentation-level) macros are ignored: .PD,.DT.

The .RS/.RE macros are translated differently depending on whether or not they precede
list markup. When .RS occurs just before .TP or .IP the result is nested lists. Otherwise,
the .RS/.RE pair is translated into a Blockquote tag-pair.

.DS/.DE is not part of the documented man macro set, but is recognized because it shows up
with some frequency on legacy man pages from older Unixes.

Certain extension macros originally defined under Ultrix are translated structurally,
including those that occasionally show up on the manual pages of Linux and other
open-source Unixes. .EX/.EE (and the synonyms .Ex/.Ee), .Ds/.De,

.NT/.NE, .PN, and .MS are translated structurally.

The following extension macros used by the X distribution are also recognized and
translated structurally: .FD, .FN, .IN, .ZN, .hN, and .C{/.C} The .TA and .IN requests are
ignored.

When the man macros are active, any .Pp macro definition containing the request .PP will
be ignored. and all instances of .Pp replaced with .PP. Similarly, .Tp will be replaced
with .TP. This is the least painful way to deal with some frequently-encountered
stereotyped wrapper definitions that would otherwise cause serious interpretation problems

Known problem areas with man translation:

· Weird uses of .TP. These will sometime generate invalid XML and sometimes result in a
FIXME comment in the generated XML (a warning message will also go to standard error).

· It is debatable how the man macros .HP and .IP without tag should be translated. We
treat them as an ordinary paragraph break. We could visually simulate a hanging
paragraph with list markup, but this would not be a structural translation.

Pod2man Translation
doclifter recognizes the extension macros produced by pod2man (.Sh, .Sp, .Ip, .Vb, .Ve)
and translates them structurally.

The results of lifting pages produced by pod2man should be checked carefully by eyeball,
especially the rendering of command and function synopses. Pod2man generates rather
perverse markup; doclifter's struggle to untangle it is sometimes in vain.

If possible, generate your DocBook from the POD sources. There is a pod2docbook module on
CPAN that does this.

Tkman Translation
doclifter recognizes the extension macros used by the Tcl/Tk documentation system: .AP,
.AS, .BS, .BE, .CS, .CE, .DS, .DE, .SO, .SE, .UL, .VS, .VE. The .AP, .CS, .CE, .SO, .SE,
.UL, .QW and .PQ macros are translated structurally.

Mandoc Translation
doclifter should be able to do an excellent job on most mdoc(7) pages, because this macro
package expresses a lot of semantic structure.

Known problems with mandoc translation: All .Bd/.Ed display blocks are translated as
LiteralLayout tag pairs .

Ms Translation
doclifter does a good job on most ms pages. One weak spot to watch out for is the
generation of Author and Affiliation tags. The heuristics used to mine this information
out of the .AU section work for authors who format their names in the way usual for
English (e.g. "M. E. Lesk", "Eric S. Raymond") but are quite brittle.

For a document to be recognized as containing ms markup, it must have the extension .ms.
This avoids problems with false positives.

The .TL, .AU, .AI, and .AE macros turn into article metainformation in the expected way.
The .PP, .LP, .SH, and .NH macros turn into paragraph and section structure. The tagged
form of .IP is translated either as a VariableList (usually) or ItemizedList (if the tag
is the troff bullet or square character); the untagged version is treated as an ordinary
paragraph break.

The .DS/.DE pair is translated to a LiteralLayout tag pair . The .FS/.FE pair is
translated to a Footnote tag pair. The .QP/.QS/.QE requests define BlockQuotes.

The .UL font change is mapped to U. .SM and .LG become numeric plus or minus size steps
suffixed to the Remap attribute.

The .B1 and .B2 box macros are translated to a Sidebar tag pair.

All macros relating to page footers, multicolumn mode, and keeps are ignored (.ND, .DA,
.1C, .2C, .MC, .BX, .KS, .KE, .KF). The .R, .RS, and .RE macros are ignored as well.

Me Translation
Translation of me documents tends to produce crude results that need a lot of
hand-hacking. The format has little usable structure, and documents written in it tend to
use a lot of low-level troff macros; both these properties tend to confuse doclifter.

For a document to be recognized as containing me markup, it must have the extension .me.
This avoids problems with false positives.

The following macros are translated into paragraph breaks: .lp, .pp. The .ip macro is
translated into a VariableList. The .bp macro is translated into an ItemizedList. The .np
macro is translated into an OrderedList.

The b, i, and r fonts are mapped to emphasis tags with B, I, and R Remap attributes. The
.rb ("real bold") font is treated the same as .b.

.q(/.q) is translated structurally .

Most other requests are ignored.

Mm Translation
Memorandum Macros documents translate well, as these macros carry a lot of structural
information. The translation rules are tuned for Memorandum or Released Paper styles;
information associated with external-letter style will be preserved in comments.

For a document to be recognized as containing mm markup, it must have the extension .mm.
This avoids problems with false positives.

The following highlight macros are translated int Emphasis tags: .B, .I, .R, .BI, .BR,
.IB, .IR, .RB, .RI.

The following macros are structurally translated: .AE, .AF, .AL, .RL, .APP, .APPSK, .AS,
.AT, .AU, .B1, .B2, .BE, .BL, .ML, .BS, .BVL, .VL, .DE, .DL .DS, .FE, .FS, .H, .HU, .IA,
.IE, .IND, .LB, .LC, .LE, .LI, .P, .RF, .SM, .TL, .VERBOFF, .VERBON, .WA, .WE.

The following macros are ignored:

.)E, .1C, .2C, .AST, .AV, .AVL, .COVER, .COVEND, .EF, .EH, .EDP, .EPIC, .FC, .FD, .HC,
.HM, .GETR, .GETST, .HM, .INITI, .INITR, .INDP, .ISODATE, .MT, .NS, .ND, .OF, .OH, .OP,
.PGFORM, .PGNH, .PE, .PF, .PH, .RP, .S, .SA, .SP, .SG, .SK, .TAB, .TB, .TC, .VM, .WC.

The following macros generate warnings: .EC, .EX, .FG, .GETHN, .GETPN, .GETR, .GETST, .LT,
.LD, .LO, .MOVE, .MULB, .MULN, .MULE, .NCOL, .nP, .PIC, .RD, .RS, .RE, .SETR

.BS/.BE and .IA/.IE pairs are passed through. The text inside them may need to be deleted
or moved.

The mark argument of .ML is ignored; the following list id formatted as a normal
ItemizedList.

The contents of .DS/.DE or .DF/.DE gets turned into a Screen display. Arguments
controlling presentation-level formatting are ignored.

Mwww Translation
The mwww macros are an extension to the man macros supported by groff(1) for producing web
pages.

The URL, FTP, MAILTO, FTP, IMAGE, TAG tags are translated structurally. The HTMLINDEX,
BODYCOLOR, BACKGROUND, HTML, and LINE tags are ignored.

TBL Translation
All structural features of TBL tables are translated, including both horizontal and
vertical spanning with ‘s’ and ‘^’. The ‘l’, ‘r’, and ‘c’ formats are supported; the ‘n’
column format is rendered as ‘r’. Line continuations with T{ and T} are handled correctly.
So is .TH.

The expand, box, doublebox, allbox, center, left, and right options are supported. The GNU
synonyms frame and doubleframe are also recognized. But the distinction between single and
double rules and boxes is lost.

Table continuations (.T&) are not supported.

If the first nonempty line of text immediately before a table is boldfaced, it is
interpreted as a title for the table and the table is generated using a table and title.
Otherwise the table is translated with informaltable.

Most other presentation-level TBL commands are ignored. The ‘b’ format qualifier is
processed, but point size and width qualifiers are not.

Pic Translation
PIC sections are translated to SVG. doclifter calls out to pic2plot(1) to accomplish
this; you must have that utility installed for PIC translation to work.

Eqn Translation
EQN sections are filtered into embedded MathML with eqn -TMathML if possible, otherwise
passed through enclosed in LiteralLayout tags. After a delim statement has been seen,
inline eqn delimiters are translated into an XML processing instruction. Exception: inline
eqn equations consisting of a single character are translated to an Emphasis with a Role
attribute of eqn.

Troff Translation
The troff translation is meant only to support interpretation of the macro sets. It is not
useful standalone.

The .nf and .fi macros are interpreted as literal-layout boundaries. Calls to the .so
macro either cause inclusion or are translated into XML entity inclusions (see above).
Calls to the .ul and .cu macros cause following lines to be wrapped in an Emphasis tag
with a Remap attribute of "U". Calls to .ft generate corresponding start or end emphasis
tags. Calls to .tr cause character translation on output. Calls to .bp generate a
BeginPage tag (in paragraphed text only). Calls to .sp generate a paragraph break (in
paragraphed text only). Calls to .ti wrap the following line in a BlockQuote These are the
only troff requests we translate to DocBook. The rest of the troff emulation exists
because macro packages use it internally to expand macros into elements that might be
structural.

Requests relating to macro definitions and strings (.ds, .as, .de, .am, .rm, .rn, .em) are
processed and expanded. The .ig macro is also processed.

Conditional macros (.if, .ie, .el) are handled. The built-in conditions o, n, t, e, and c
are evaluated as if for nroff on page one of a document. The m, d, and r troff
conditionals are also interpreted. String comparisons are evaluated by straight textual
comparison. All numeric expressions evaluate to true.

The extended groff requests cc, c2, ab, als, do, nop, and return and shift are
interpreted. Its .PSPIC extension is translated into a MediaObject.

The .tm macro writes its arguments to standard error (with -t). The .pm macro reports on
defined macros and strings. These facilities may aid in debugging your translation.

Some troff escape sequences are lifted:

1. The \e and \\ escapes become a bare backslash, \. a period, and \- a bare dash.

2. The troff escapes \^, \`, \' \&, \0, and \| are lifted to equivalent ISO special
spacing characters.

3. A \ followed by space is translated to an ISO non-breaking space entity.

4. A \~ is also translated to an ISO non-breaking space entity; properly this should be a
space that can't be used for a linebreak but stretches like ordinary whitepace during
line adjustment, but there is no ISO or Unicode entity for that.

5. The \u and \d half-line motion vertical motion escapes, when paired, become
Superscript or Subscript tags.

6. The \c escape is handled as a line continuation. in circumstances where that matters
(e.g. for token-pasting).

7. The \f escape for font changes is translated in various context-dependent ways. First,
doclifter looks for cliches involving font changes that have semantic meaning, and
lifts to a structural tag. If it can't do that, it generates an Emphasis tag.

8. The \m[] extension is translated into a phrase span with a remap attribute carrying
the color. Note: Stylesheets typically won't render this!

9. Some uses of the \o request are translated: pairs with a letter followed by one of the
characters ` ' : ^ o ~ are translated to combining forms with diacriticals acute,
grave, umlaut, circumflex, ring, and tilde respectively if the corresponding Latin-1
or Latin-2 character exists as an ISO literal.

Other escapes than these will yield warnings or errors.

All other troff requests are ignored but passed through into XML comments. A few (such as
.ce) also trigger a warning message.

PORTABILITY CHECKING

When portability checking is enabled, doclifter emits portability warnings about markup
which it can handle but which will break various other viewers and interpreters.

1. At level 1, it will warn about constructions that would break man2html(1), (the C
program distributed with Linux man(1), not the older and much less capable Perl
script). A close derivative of this code is used in GNOME yelp. This should be the
minimum level of portability you aim for, and corresponds to what is recommended on
the groff_man(7) manual page.

2. At level 2, it will warn about constructions that will break portability back to the
Unix classic tools (including long macro names and glyph references with \[]).

SEMANTIC ANALYSIS

doclifter keeps two lists of semantic hints that it picks up from analyzing source
documents (especially from parsing command and function synopses). The local list
includes:

· Names of function formal arguments

· Names of command options

Local hints are used to mark up the individual page from which they are gathered. The
global list includes:

· Names of functions

· Names of commands

· Names of function return types

If doclifter is applied to multiple files, the global list is retained in memory. You can
dump a report of global hints at the end of the run with the -h option. The format of the
hints is as follows:

.\" | mark <phrase> as <markup>

where <phrase> is an item of text and <markup> is the DocBook markup text it should be
wrapped with whenever it appeared either highlighted or as a word surrounded by whitespace
in the source text.

Hints derived from earlier files are also applied to later ones. This behavior may be
useful when lifting collections of documents that apply to a function or command library.
What should be more useful is the fact that a hints file dumped with -h can be one of the
file arguments to doclifter; the code detects this special case and does not write XML
output for such a file. Thus, a good procedure for lifting a large library is to generate
a hints file with a first run, inspect it to delete false positives, and use it as the
first input to a second run.

It is also possible to include a hints file directly in a troff sourcefile. This may be
useful if you want to enrich the file by stages before converting to XML.

TROUBLESHOOTING

doclifter tries to warn about problems that it can can diagnose but not fix by itself.
When it says "look for FIXME", do that in the generated XML; the markup around that token
may be wrong.

Occasionally (less than 2% of the time) doclifter will produce invalid DocBook markup even
from correct troff markup. Usually this results from strange constructions in the source
page, or macro calls that are beyond the ability of doclifter's macro processor to get
right. Here are some things to watch for, and how to fix them:

Malformed command synopses.
If you get a message that says "command synopsis parse failed", try rewriting the synopsis
in your manual page source. The most common cause of failure is unbalanced [] groupings, a
bug that can be very difficult to notice by eyeball. To assist with this, the error
message includes a token number in parentheses indicating on which token the parse failed.

For more information, use the -v option. This will trigger a dump telling you what the
command synopsis looked like after preprocessing, and indicate on which token the parse
failed (both with a token number and a caret sign inserted in the dump of the synopsis
tokens). Try rewriting the synopsis in your manual page source. The most common cause of
failure is unbalanced [] groupings, a bug that can be very difficult to notice by eyeball.
To assist with this, the error token dump tries to insert ‘$’ at the point of the last
nesting-depth increase, but the code that does this is failure-prone.

Confusing macro calls.
Some manual page authors replace standard requests (like .PP, .SH and .TP) with versions
that do different things in nroff and troff environments. While doclifter tries to cope
and usually does a good job, the quirks of [nt]roff are legion and confusing macro calls
sometimes lead to bad XML being generated. A common symptom of such problems is unclosed
Emphasis tags.

Malformed list syntax.
The manual-page parser can be confused by .TP constructs that have header tags but no
following body. If the XML produced doesn't validate, and the problem seems to be a
misplaced listitem tag, try using the verbose (-v) option. This will enable line-numbered
warnings that may help you zero in on the problem.

Section nesting problems with SS.
The message "possible section nesting error" means that the program has seen two adjacent
subsection headers. In man pages, subsections don't have a depth argument, so doclifter
cannot be certain how subsections should be nested. Any subsection heading between the
indicated line and the beginning of the next top-level section might be wrong and require
correcting by hand.

Bad output with no doclifter error message
If you're translating a page that uses user-defined macros, and doclifter fails to
complain about it but you get bad output, the first thing to do is simplify or eliminate
the user-defined macros. Replace them with stock requests where possible.

IMPROVING TRANSLATION QUALITY

There are a few constructions that are a good idea to check by hand after lifting a page.

Look near the BlockQuote tags. The troff temporary indent request (.ti) is translated into
a BlockQuote wrapper around the following line. Sometimes LiteralLayout or ProgramListing
would be a better translation, but doclifter has no way to know this.

It is not possible to unambiguously detect candidates for wrapping in a DocBook option tag
in running text. If you care, you'll have to check for these and fix them by hand.

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