PX(1) General Commands Manual PX(1)NAME
px - Pascal interpreter
px [ obj [ argument ... ] ]
Px interprets the abstract machine code generated by pi. The first argument is the file to be interpreted, and defaults to obj; remaining
arguments are available to the Pascal program using the built-ins argv and argc. Px is also invoked by pix when running `load and go'.
If the program terminates abnormally an error message and a control flow backtrace are printed. The number of statements executed and
total execution time are printed after normal termination. The p option of pi suppresses all of this except the message indicating the
cause of abnormal termination.
obj default object file
pmon.out profile data file
Berkeley Pascal User's Manual
Most run-time error messages are self-explanatory. Some of the more unusual ones are:
Reference to an inactive file
A file other than input or output was used before a call to reset or rewrite.
Statement count limit exceeded
The limit of 500,000 executed statements (which prevents excessive looping or recursion) has been exceeded.
Bad data found on integer read
Bad data found on real read
Usually, non-numeric input was found for a number. For reals, Pascal requires digits before and after the decimal point so that num-
bers like `.1' or `21.' evoke the second diagnostic.
panic: Some message
Indicates a internal inconsistency detected in px probably due to a Pascal system bug. Charles B. Haley, William N. Joy, and Ken
Calls to the procedures dispose and linelimit are ignored.
Post-mortem traceback is not limited; infinite recursion leads to almost infinite traceback.
Because interrupts sometimes find the system in the middle of a procedure or function entry or exit, the error backtrace on an interrupt is
occasionally meaningless. The current line is, however, always correct; only the call backtrace and the name of the current routine may be
3rd Berkeley DistributionPX(1)
Check Out this Related Man Page
TANGLE(1) General Commands Manual TANGLE(1)NAME
tangle - translate WEB to Pascal
tangle webfile[.web] [ changefile[.ch] ]
This manual page is not meant to be exhaustive. The complete documentation 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 com-
piler (e.g., pc(1)). The output file is all in lower case and 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
program 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 simple, although adequate, macro facility that permits a Pascal pro-
gram 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 exten-
sion). 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 file name.
SEE ALSO 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, 1984.
Wayne Sewell, Weaving a Program, Van Nostrand Reinhold, 1989, ISBN 0-442-31946-0.
Donald E. Knuth, TeX: The Program (Volume B of Computers and Typesetting), Addison-Wesley, 1986, ISBN 0-201-13437-3.
Donald E. Knuth, Metafont: The Program (Volume D of Computers and Typesetting), 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 subject 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 7.3.1 12 February 1993 TANGLE(1)