As I see ${1+"$@"} can be simplified to "$@". The only difference is that in the first case only $1 will be checked whether it is set.
Yes, that's my idea as well. If there's at least one argument, $1 is set and ${1+"$@"} first expands to "$@" which then expands to $1 $2 $3 .... If $1 isn't set ${1+"$@"} expands to nothing. In either case, it's the same as "$@". There might be some shell somewhere that makes a difference, but according my reading of a manual found on the Interwebs, even in the Bourne Shell on System 7 both ${1+"$@"} and "$@" are identical. The POSIX standard also says that in the absence of positional parameters, "$@" expands to nothing.
I'm not really knowledgeable in the c shell, so I can't explain now the gubbin designed for sh and csh at the same time.
I'd be surprised if the gubbin actually worked on csh. AFAIK, it doesn't do ${foo+bar} style parameter expansion (but I don't have a csh laying around to try it on).

Perhaps the ${1+"$@"} is just a piece of cargo cult. Noone is really sure if it's going to break on some system somewhere, and just leaves it as is, instead of replacing it with "$@". It's not that there's a huge savings.

In reply to Re^2: Running Under Some Shell by JavaFan
in thread Running Under Some Shell by Xiong

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