Re: configure script question ?

[June Fang]

and what's more, the entire lines:
      15  if test -n "${ZSH_VERSION+set}" && (emulate sh) >/dev/null 2>&1; then
      16   emulate sh
i guess it means execuate "emulate sh" in subshell, and
if it success, do it in our current shell ? am i right ?


On 2/24/06, June Fang <address@hidden> wrote:
> sorry in advance if stupid question, but i am a really new bie.
>
> i found the following shell script in the configure file of autoconf-2.59
> but dose that means ?
>      15  if test -n "${ZSH_VERSION+set}" && (emulate sh) >/dev/null 2>&1; then
>      16   emulate sh
>      17   NULLCMD=:
>      18   # Zsh 3.x and 4.x performs word splitting on ${1+"$@"}, which
>      19   # is contrary to our usage.  Disable this feature.
>      20   alias -g '${1+"$@"}'='"$@"'
>      21 elif test -n "${BASH_VERSION+set}" && (set -o posix)
> >/dev/null 2>&1; then
>      22   set -o posix
>      23 fi
>
> i know ${ZSH_VERSION} means variable substituting;
> and ${ZSH_VERSION:+set} means "If parameter is null or unset, nothing
>                                        ~~ Note the `:`
> is substituted, otherwise the expansion of word is substituted."
>     ---- from Bash reference manual
>
> but what dose ${ZSH_VERSION+set} without the `:` means ?
>
> thanks in advance.
>