manweb (1) - Linux Man Pages
manweb: browse netpbm (and other) documentation
manweb [-config=configfile] [topic [ subtopic ... ] ]
manwebThis gets a master index of documentation.
manweb netpbmThis gets the main documentation page for the Netpbm package, with hyperlinks to the rest of the documentation.
manweb netpbm pngtopamThis goes directly to the documentation page for the Pngtopam program in the Netpbm package.
manweb pngtopamThis also goes directly to the documentation page for the Pngtopam program in the Netpbm package, if that's what would run in response to a pngtopam shell command (your PATH environment variable is involved).
manweb 3 fopenThis gets the traditional man page for the fopen() subroutine using man.
manweb cpThis gets the GNU Info manual for the cp program, using info.
manweb displays reference documentation via quick shell commands. It is a replacement for the well-known man.
Differences Between Man and Manweb
manweb's advantages over man are:
You can access documentation that is on the worldwide web instead of
having locally installed copies. This saves installation work and gets
you more current documentation.
Documentation can be in HTML, which is more widely known, more widely
useful, and more expressive than the nroff/troff format used by
manweb puts your topics in a tree for multilevel documentation.
man is intended for a single level of documentation. For
example, you can have a man page for each shell command, but not for
the subcommands of a shell command. And you cannot properly have
man pages for the members of multiple subroutine libraries.
Documentation can be hyperlinked.
Web servers need not be involved -- the documentation can be in local files. Graphics need not be involved -- the lynx browser works fine in the same kind of terminals in which man works.
manweb finds the documentation you specify and calls a web browser of your choice to display it. The documentation manweb finds can be either an HTML file on your system, in which case, manweb gives a file: URL to your browser, or an explicit URL. That explicit URL might be an http: URL referring to an HTML file on a web server somewhere, or anything else your browser understands.
If manweb finds neither an HTML file nor a URL, but your parameters look like they could mean something to man, manweb calls man. Therefore, you can use a single command to access the vast body of traditional man pages, plus any newer manweb documentation. You can make "man" a shell alias of "manweb".
manweb finds Info documentation as well. It looks for the topic you specify as an Info topic after looking for HTML and URL documentation and before running man. If manweb finds a corresponding Info topic, it runs the program info on it. Info is the documentation system that the GNU project invented to, among other things, replace traditional Unix man pages. However, HTML and the Worldwide Web were invented shortly afterward, so Info fizzled. But there is still a lot of GNU software that is documented as Info topics.
How Manweb Finds Documentation
manweb passes a URL to a web browser. This section tells how your manweb invocation parameters turn into that URL.
manweb's search starts in the "web directory" directory. That's either the value of the webdir keyword in your manweb configuration file, or the default /usr/man/web.
Your invocation parameters form a "topic chain." Going from left to right, the first parameter is the main topic, the 2nd is a subtopic of the main topic, and so on.
Let's look at the simple case where you specify exactly one parameter -- a main topic. We'll call it maintopic and look at 4 ways manweb might find it:
If manweb finds a file named maintopic.html
in the web directory, the URL manweb passes to the
browser is just a file: URL that specifies that .html
If there's no .html file, but there is a file named
maintopic.url, the contents of the first line of
that .url file is what manweb passes to the browser. It
doesn't interpret the contents at all. If it's garbage, the
browser chokes on it.
If there's neither a .html nor a .url file, but there is a
directory named maintopic, manweb looks in the
directory for a file named index.html. If there is one,
manweb passes a file: URL specifying that
index.html file to the browser. If there's no
index.html, manweb uses a file: URL that
specifies the directory itself.
If manweb doesn't find documentation in any of the
above ways, it searches your executable search path (as defined
by your PATH environment variable) for a program named
maintopic. If it finds one, it looks in the directory
that contains the program for a file named doc.url. If
it finds one, it appends maintopic.html to the
first line of the file and passes that to the browser. Unless
the first line does not end with a slash -- in that
case, manweb passes the first line of the file unmodified
to the browser.
It gets a little more interesting when you have subtopics. Looking at each of the 4 cases above:
Where maintopic.html exists, subtopics are invalid.
You get a warning message and the subtopics are ignored.
Where there's no .html file but maintopic.url exists,
manweb appends the subtopic chain to the URL it gets from the
.url file as in the following example: .url file contains
http://acme.com/productxyz/ and subtopics are
database. The URL manweb passes to the browser is
manweb doesn't check that this kind of appendage makes
any sense for the URL in question, except that if the URL in the
.url file doesn't end with a slash (/), manweb
issues a warning and doesn't append anything (ignores the subtopics).
Where there's neither a .html file nor a .url file, but there's a
maintopic directory, manweb recurses into that
directory and begins a whole new search using the first subtopic
as the main topic and the rest of the subtopics as subtopics of that.
When there are subtopics, the PATH thing doesn't make sense,
so manweb doesn't do it.
If you give subtopics, the PATH thing described above for one topic doesn't apply.
If you give no parameters at all, manweb generates a URL for the web directory itself as described above for subdirectories.
The above is simplified by the assumption of a single web directory. In reality, the webdir keyword in the configuration file can specify a chain of web directories. manweb searches each one in turn, doing all the kinds of searches in each web directory before moving on to the next one.
The Configuration File
The default location of the manweb configuration file is /etc/manweb.conf. But you can override this with the environment variable MANWEB_CONF_FILE, and override that with the -config invocation option.
Lines starting with "#" are comments and are ignored, as are blank lines.
All other lines have the format keyword=value. The keywords defined are:
A colon-delimited sequence of directories to search for
documentation as described above. If you
don't specify this, the default is /usr/man/web alone.
The file specification manweb of the web browser manweb
is to invoke
to display documentation (except when it uses man to display
a conventional man page).
If the file specification does not include a slash, manweb
searches for the file in the PATH search path.
If you don't specify this, the default is the value of the
BROWSER environment variable, and if that is not set,
# Configuration file for Manweb webdir=/usr/share/manweb browser=netscape