Fix quoting of $@ and don't exec in the background.

"$@" expands to "$1" "$2" "$3" which preserves spaces calling the chained
command.

"$*" expands to "$1 $2 $3" which makes sense for the echo argument.

This commit also switches to simply calling the chained command in the 
foreground, instead of exec in the background with wait which is a complicated
way of doing nothing.