Mike Frysinger wrote:
> On Monday 24 September 2007, Donnie Berkholz wrote:
>>
>> You could use C-style syntax here:
>>
>> (( use_errors++ ))
>>
>> I find it a bit more readable.
>
> i like to get anal and use ((++use_errors))
>
> then again, it may also be more readable like so:
> use_errors=false
> if ... ; then
> ...
> use_errors=true
> fi
> if ... ; then
> ...
> use_errors=true
> fi
> ${use_errors} && die "..."
> -mike
Integer arithmetic is generally quicker:
((use_errors++)) [or: use_errors=1 ]
..
((use_errors)) && die 'meh'
-- although true and false are builtins in this case.
For stuff like for ((i=0;i<n;i++)) arithmetical context[1] is significantly
quicker than for i in {0..15} say, and more flexible (variable bound and
step-size, if desired.)
The boolean test on an integer eg ((use_errors)) is a metaphor I use a lot,
eg: ((quiet)) || echo oops; ((verbose>1)) && echo blah
It's handy as unset vars test to false, and also as the usual boolean values
apply, ie 0 is false, anything else is true. (Outside this context 0 is
true [success from cmd] and anything else is false [error code].) And ofc,
you don't need to put $ in front of your standard variables in this
context.
[1] http://wooledge.org/mywiki/ArithmeticExpression
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