Re: Safe scripting

[Atom Smasher <atom@xxxxxxxxxxx>]

On Wed, 21 Jan 2009, Richard Hartmann wrote:

> Atom's solution is rather magic, but works very well. If you want to be
> portable, you can also do
>
> cd foo       || exit 10
> rm bar       || exit 11
> cd foobar    || exit 12
> rm foobarbar || exit 13
>
> That is very basic and can be extended, for example with
>
> cd foo       || my_handler 'error foo' '10'
>
> function my_handler() {
> 	echo $1 $2
> }
>
> etc, etc.
===================

you can also sprinkle some magic on that, and it still looks portable...

error () {
	print "something went wrong on line ${1}" >&2
	exit $[ (${1} - 1) % 127 + 1 ]
}
 cd foo		|| error ${LINENO}
 cd foobar	|| error ${LINENO}
 cd baz		|| error ${LINENO}

the extra math in the exit value would help identify the line that failed 
using the exit status, but keep the value within a sane range. for scripts 
shorter than 127 lines "exit ${1}" would suffice.

i ~think~ 127 is the correct value for the mod operation, keeping the exit 
status within the range of 1-127, and than wrapping. i'm sure someone here 
can point out if 128 or even 255 is a reasonable value.


--
        ...atom

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