NAME

px − Pascal interpreter

SYNOPSIS

px [ objfile [ arguments ] ]

DESCRIPTION

Px interprets the abstract machine code generated by pi.  The first argument is the file to be interpreted, and defaults to objfile; 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. 

FILES

objdefault object file
pmon.outprofile data file

SEE ALSO

Berkeley Pascal User’s Manual, in Volume III of the UNIX Programmer’s Manual. 
pi(1), pix(1)

DIAGNOSTICS

Most runtime error messages are self-explanatory.  Others include the following:

“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 numbers such as “.1” or “21.” evoke the second diagnostic.

“panic: message”
Indicates an internal inconsistency detected in px, probably due to a Pascal system bug. 

“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.

BUGS

Post mortem traceback is not limited; infinite recursion leads to almost infinite traceback. 

3rd Berkeley Distribution  —  1 August 1985