TANGLE(1) General Commands Manual TANGLE(1)
tangle - translate WEB to Pascal
tangle [options] webfile[.web] [changefile[.ch]]
This manual page is not meant to be exhaustive. The complete documen-
tation for this version of TeX can be found in the info file or manual
Web2C: A TeX implementation.
The tangle program converts a Web source document into a Pascal program
that may be compiled in the usual way with the on-line Pascal compiler
(e.g., pc(1)). The output file is packed into lines of 72 characters
or less, with the only concession to readability being the termination
of lines at semicolons when this can be done conveniently.
The Web language allows you to prepare a single document containing all
the information that is needed both to produce a compilable Pascal pro-
gram and to produce a well-formatted document describing the program in
as much detail as the writer may desire. The user of Web must be
familiar with both TeX and Pascal. Web also provides a relatively sim-
ple, although adequate, macro facility that permits a Pascal program to
be written in small easily-understood modules.
The command line should have either one or two names on it. The first
is taken as the Web file (and .web is added if there is no extension).
If there is another name, it is a change file (and .ch is added if
there is no extension). The change file overrides parts of the Web
file, as described in the Web system documentation.
The output files are a Pascal file and a string pool file, whose names
are formed by adding .p and .pool respectively to the root of the Web
This version of tangle understands the following options. Note that
some of these options may render the output unsuitable for processing
by a Pascal compiler.
--help Print help message and exit.
Compare only the first number characters of identifiers when
checking for collisions. The default is 32, the original tangle
When checking for collisions between identifiers, honor the set-
tings of the --lowercase, --mixedcase, --uppercase, and --under-
line options. This is the default.
Convert all identifiers to lowercase.
Retain the case of identifiers. This is the default.
When checking for collisions between identifiers, strip under-
lines and convert all identifiers to uppercase first.
Retain underlines (also known as underscores) in identifiers.
Convert all identifiers to uppercase. This is the behaviour of
the original tangle.
Print version information and exit.
The environment variable WEBINPUTS is used to search for the input
files, or the system default if WEBINPUTS is not set. See tex(1) for
the details of the searching.
pc(1), pxp(1) (for formatting tangle output when debugging), tex(1).
Donald E. Knuth, The Web System of Structured Documentation.
Donald E. Knuth, Literate Programming, Computer Journal 27, 97-111,
Wayne Sewell, Weaving a Program, Van Nostrand Reinhold, 1989, ISBN
Donald E. Knuth, TeX: The Program (Volume B of Computers and Typeset-
ting), Addison-Wesley, 1986, ISBN 0-201-13437-3.
Donald E. Knuth, Metafont: The Program (Volume D of Computers and Type-
setting), Addison-Wesley, 1986, ISBN 0-201-13438-1.
These last two are by far the largest extant examples of Web programs.
There is an active Internet electronic mail discussion list on the sub-
ject of literate programming; send a subscription request to litprog-
email@example.com to join.
Web was designed by Donald E. Knuth, based on an earlier system called
DOC (implemented by Ignacio Zabala). The tangle and weave programs are
themselves written in Web. The system was originally ported to Unix at
Stanford by Howard Trickey, and at Cornell by Pavel Curtis.
Web2C 2017 16 June 2015 TANGLE(1)
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