standardized error messages

[John Quarterman]

From: John Quarterman (moderator) <std-unix-request at ut-sally>
Topic: Re: standardized error messages

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Date: Sun, 21 Jul 85 05:19:11 pdt
From: seismo!nsc!daisy!david (David Schachter)
To: ut-sally!jsq
Subject: Re: standardized error messages
In-Reply-To: <2391 at ut-sally.UUCP>

Daisy's version of the UNIX(tm) operating system has a standard
way of handling error reporting.  You call a system routine,
passing it an error file number and an error status.  You also
pass a flag saying how to handle the error and substitution var-
iables.  The system looks up the error file number in a table to 
get the names of the error file.  It then looks up in the file the
appropriate error message, using a simple transformation of the
error status as the key.  The strings in the error file are sim-
ilar in format to the 'printf' function thus allowing you to
substitute variables into the error message.
 
The flag you pass tells the system whether to display the message,
add it to the stack, display the entire stack (clearing it), or
jump to the machine monitor with a fatal error.  Obviously, the
latter case is used only when the error is on the order of "system
corrupt."
  
You can also pass an error port id if you do not wish the message
to go to std_err.
  
A subtle advantage of this is that all error messages reside in
external text files, not compiled into the code of the programs.
This results in faster loading, less memory usage, and makes it
easy to change error messages and to enforce consistent style.
  
[This does not represent official policy by Daisy Systems.  The
author speaks only for himself.] {"Where there's a will, there's
a won't."}

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Discussions-Of: UNIX standards, particularly the IEEE P1003 draft standard.
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