— Macro: AC_CHECK_MEMBER (aggregate.member, [action-if-found], [action-if-not-found], [includes = ‘AC_INCLUDES_DEFAULT’])

Check whether member is a member of the aggregate aggregate. If no includes are specified, the default includes are used (see Default Includes).

          AC_CHECK_MEMBER([struct passwd.pw_gecos], [],
                          [AC_MSG_ERROR([we need `passwd.pw_gecos'])],
                          [[#include <pwd.h>]])

You can use this macro for submembers:

          AC_CHECK_MEMBER(struct top.middle.bot)

This macro caches its result in the ac_cv_member_aggregate_member variable, with characters not suitable for a variable name mapped to underscores.

— Macro: AC_CHECK_MEMBERS (members, [action-if-found], [action-if-not-found], [includes = ‘AC_INCLUDES_DEFAULT’])

Check for the existence of each ‘aggregate.member’ of members using the previous macro. When member belongs to aggregate, define HAVE_aggregate_member (in all capitals, with spaces and dots replaced by underscores). If action-if-found is given, it is executed for each of the found members. If action-if-not-found is given, it is executed for each of the members that could not be found.

includes is a series of include directives, defaulting to AC_INCLUDES_DEFAULT (see Default Includes), which are used prior to the members under test.

This macro uses M4 lists:

          AC_CHECK_MEMBERS([struct stat.st_rdev, struct stat.st_blksize])