dnl @synopsis AC_CHECK_ENVVAR dnl dnl This macro tests if a particular environment variable is defined. dnl Warning if not. dnl dnl Example: dnl dnl AC_CHECK_ENVVAR(foo) dnl AC_DEFUN([AC_CHECK_ENVVAR],[dnl AC_MSG_CHECKING([variable $1]) if test -z @S|@$1; then AC_MSG_RESULT([no]) AC_MSG_WARN([environment variable $1 not defined]) else AC_MSG_RESULT([@S|@$1]) fi ])