lexgrog - parse header information in man pages
lexgrog [-m|-c] [-fhwV] file ...
lexgrog is an implementation of the traditional "groff guess" utility
in lex. It reads the list of files on its command line as either man
page source files or preformatted "cat" pages, and displays their name
and description as used by apropos and whatis, the list of preprocessing
filters required by the man page before it is passed to nroff or
troff, or both.
If its input is badly formatted, lexgrog will print "parse failed";
this may be useful for external programs that need to check man pages
for correctness. If one of lexgrog's input files is "-", it will read
from standard input; if any input file is compressed, a decompressed
version will be read automatically.
-m, --man
Parse input as man page source files. This is the default if
neither --man nor --cat is given.
-c, --cat
Parse input as preformatted man pages ("cat pages"). --man and
--cat may not be given simultaneously.
-w, --whatis
Display the name and description from the man page's header, as
used by apropos and whatis. This is the default if neither
--whatis nor --filters is given.
-f, --filters
Display the list of filters needed to preprocess the man page
before formatting with nroff or troff.
-h, --help
Print a help message and exit.
-V, --version
Display version and author information.
0 Successful program execution.
1 Usage error.
2 lexgrog failed to parse one or more of its input files.
$ lexgrog man.1
man.1: "man - an interface to the on-line reference manuals"
$ lexgrog -fw man.1
man.1 (t): "man - an interface to the on-line reference manuals"
$ lexgrog -c whatis.cat1
whatis.cat1: "whatis - display manual page descriptions"
$ lexgrog broken.1
broken.1: parse failed
mandb (which uses the same code as lexgrog) parses the NAME section at
the top of each manual page looking for names and descriptions of the
features documented in each. While the parser is quite tolerant, as it
has to cope with a number of different forms that have historically
been used, it may sometimes fail to extract the required information.
A correct NAME section looks something like this:
.SH NAME
foo \- program to do something
Some manual pagers require the `\-' to be exactly as shown; mandb is
more tolerant, but for compatibility with other systems it is nevertheless
a good idea to retain the backslash.
On the left-hand side, there may be several names, separated by commas.
The text on the right-hand side is free-form, and may be spread over
multiple lines. If several features with different descriptions are
being documented in the same manual page, the following form is therefore
used:
.SH NAME
foo, bar \- programs to do something
.br
baz \- program to do nothing
(A macro which starts a new paragraph, like .PP, may be used instead of
the break macro .br.)
There are several common reasons why whatis parsing fails. Sometimes
authors of manual pages replace `.SH NAME' with `.SH MYPROGRAM', and
then mandb cannot find the section from which to extract the information
it needs. Sometimes authors include a NAME section, but place
free-form text there rather than `name \- description'. However, any
syntax resembling the above should be accepted.
man(1), mandb(8), apropos(1), whatis(1).
lexgrog cannot parse files containing .so requests. These are probably
best checked by other problems, as lexgrog often does not have enough
context to know what to do with them.
The code used by lexgrog to scan man pages was written by:
Wilf. ([email protected]).
Fabrizio Polacco ([email protected]).
Colin Watson ([email protected]).
Colin Watson wrote the current incarnation of the command-line frontend,
as well as this man page.
2.3.20 07 September 2001 lexgrog(1)
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