8.2 Return Statuses

8.2 Return Statuses

The hierarchy of diagnostics is also used in the shell

commands. Each shell command returns a status which can

Tutorial

affect further processing.

Success

 status is the normal command return

Developer

status.

Warning

 status is returned if some minor problem

Reference

arose with the execution of the command.

1 Introduction

Error

 status is returned if a significant problem

2 Interface

arises during the execution of the command.

3 Scanner

However, unlike a severe error, it does 

not

  cause

4 Parser

termination of the enclosing shellscript.

5 Analyser

Severe error

 status is returned if a problem arises

6 Tangle

during the execution of the command that prevents

7 Weave

the command from delivering on its "promise". A

8 Shell

severe error causes FunnelWeb to abort the script

(and any stacked scripts) to the interactive level.

9 Commands

(However, the tolerate command allows this to be

10 Glossary

temporarily overridden).

11 References

Fatal error

 status is returned if a problem arises

that is so serious that execution of FunnelWeb

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cannot continue. A fatal error causes FunnelWeb

to abort to the operating system level.

Assertion error

 status is never returned. If an

assertion error occurs, FunnelWeb bombs out

ungracefully to the operating system. Assertion

errors should never happen. If they do, then there

is a bug in FunnelWeb.

To be precise, the status returned by each command is a vector

of numbers being the number of each of the different kinds of

diagnostic generated by the command. Usually only one kind of

diagnostic is generated. However, the fw command and a few

of the other commands can generate more than one kind of

diagnostic. These status vectors are summed internally where

they may later be accessed using the status command. However,

the current diagnostic state evaporates as soon as the next

command is encountered.

http://www.ross.net/funnelweb/reference/shell_statuses.html (1 of 2) [3/3/2000 10:46:00 PM]