On Wed, 12 May 2010 14:19:22 Mario DeFazio wrote:
> (( )) is purely for arithmetic expressions.
> I think the simplest, most readable valid "upgrade"
> to your original expression is
>
> if (( $# > 1 )) && [[ -t 0 && -t 1 ]]; then
>
> Anyway, that's how I would do it. :-)
>
Ok, that's what I was thinking. My original expression was a bit more
complex than this:
if [[ -n "$list" || ( $# -gt 1 && -t 0 && -t 1 ) ]]; then
Where list can be '' or 1
the -n "$list" can be substituted with ((list)) as long as the unset
value of $list is set to 0 - but then the expression maps to:
if (( $# > 1 )) && [[ -t 0 && -t 1 ]] || ((list)); then
which could hardly be called a simplification. I was hoping for
something like
if (( list || $# > 1 && -t 0 && -t 1 )); then
which is neater and presumably better by some abstract measure.
I can see how -t would violate the C-like syntax of arithmetic
expressions, but surely something can be used? a simple stat() function
perhaps?
It seems like there might be scope for handling at least the -X
operators in some form, and perhaps other traditional operators.
Restricting (( )) to pure maths seems to violate the spirit of shell
scripting which should make it trivial to work with files, directories
and other regular "job-control" features.
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