LEXGROG(1)                                             Manual pager utils                                             LEXGROG(1)



NAME
       lexgrog - parse header information in man pages

SYNOPSIS
       lexgrog [-m|-c] [-fhwV] [-E encoding] file ...

DESCRIPTION
       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.

OPTIONS
       -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.

       -E encoding, --encoding encoding
              Override the guessed character set for the page to encoding.

       -h, --help
              Print a help message and exit.

       -V, --version
              Display version information.

EXIT STATUS
       0      Successful program execution.

       1      Usage error.

       2      lexgrog failed to parse one or more of its input files.

EXAMPLES
         $ 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

WHATIS PARSING
       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.

       When using the traditional man macro set, 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 sys-
       tems it is nevertheless a good idea to retain the backslash.

       On the left-hand side, there may be several names, separated by commas.  Names containing whitespace will be  ignored  to
       avoid  pathological behaviour on certain ill-formed NAME sections.  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.)

       When using the BSD-derived mdoc macro set, a correct NAME section looks something like this:

              .Sh NAME
              .Nm foo
              .Nd program to do something

       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.

SEE ALSO
       man(1), mandb(8), apropos(1), whatis(1).

NOTES
       lexgrog attempts to parse files containing .so requests, but will only be able to do so correctly if the files are  prop-
       erly installed in a manual page hierarchy.

AUTHOR
       The code used by lexgrog to scan man pages was written by:

       Wilf. (G.WilfordATee.uk).
       Fabrizio Polacco (fpolaccoATdebian.org).
       Colin Watson (cjwatsonATdebian.org).

       Colin Watson wrote the current incarnation of the command-line front-end, as well as this man page.



2.5.7                                                      2010-02-16                                                 LEXGROG(1)