[haiku-development] Re: Weird Bootscript scripting problem
- From: Donn Cave <donn@xxxxxxxxxxx>
- To: haiku-development@xxxxxxxxxxxxx
- Date: Wed, 22 Apr 2009 14:09:13 -0700 (PDT)
Quoth "=?utf-8?q?Fran=C3=A7ois?= Revol" <revol@xxxxxxx>,
>> > ($? = 0 if the first button was pressed, 1 for the second and 2 for
>> > the
>> > third)
>>
>> Thanks a lot, this works more reliable when there is some debug
>> output
>
> Yes it also won't break if you change the button names :)
But it will break if you change the order, and it isn't as easy to
read and understand. Maybe more ideal,
IOPT="Installer"
DOPT="Desktop"
opt=$(/bin/alert "Run Installer, or boot to Desktop?" "$IOPT" "$DOPT")
case $opt in
$IOPT)
echo 'Launching ...
...
exit 0
;;
$DOPT)
;;
*)
echo "WTF is \"$opt\"?"
;;
esac
On the other hand, if you happen have a yes/no convention where yes is
always presented on the left, and no on the right, then you can use
"if" to test the exit status directly:
if /bin/alert "yes or no" "yes" "no"
then
... yes
else
... no
fi
> single quotes disable variable substitutions:
(and `backtick` substitution, which in modern shells can also be written $(),
syntactically more robust.)
Speaking of Bourne shell syntax weaknesses - I couldn't find anything
wrong with the script, so I could only guess that the actual Bootscript
you were running was slightly different from the patch. And I'm guessing
the difference was
if [ "$installer" = <- works
vs.
if ["$installer" = <- fails the way you describe
"[" is actually a `command', in Bourne shell syntax - it isn't punctuation
or a metacharacter or whatever you want to call it, it's just like any
alphabet character, and classically it invokes /bin/[ -- the same command
as /bin/test, but with a pro forma requirement for a trailing ']'.
Bash may substitute a builtin, I forget, but syntactically it's bound to
follow the same rules: invoke the test command, and note its exit status.
If you omit the space after [, it will try to invoke [Install.
"case" is different - it's syntactically native to the shell language,
so for example you don't have to quote the argument.
Donn
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