configure.ac |   50 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 50 insertions(+)

--- quilt.orig/configure.ac	2005-09-16 12:35:31.000000000 +0200
+++ quilt/configure.ac	2005-09-16 13:00:16.000000000 +0200
@@ -89,6 +89,56 @@
 	AC_SUBST(GREP)
     ])
 
+AC_MSG_CHECKING([whether $GREP understands -q])
+if test -z "`echo first | $GREP -q first 2>/dev/null`"; then
+	AC_MSG_RESULT(yes)
+else
+	AC_MSG_RESULT(no)
+	AC_MSG_ERROR([
+Sorry, you have a version of grep which doesn't understand -q.
+$PACKAGE_NAME needs it.  If you have access to a version of grep which does
+understand -q, you can supply its path with the '--with-grep=' option.
+])
+fi
+
+AC_MSG_CHECKING([whether $GREP understands -v])
+if test "`(echo first; echo second) | $GREP -v first 2>/dev/null`" == "second"; then
+	AC_MSG_RESULT(yes)
+else
+	AC_MSG_RESULT(no)
+	AC_MSG_ERROR([
+Sorry, you have a version of grep which doesn't understand -v.
+$PACKAGE_NAME needs it.  If you have access to a version of grep which does
+understand -v, you can supply its path with the '--with-grep=' option.
+])
+fi
+
+AC_MSG_CHECKING([whether $GREP understand -e])
+if test "x`echo -aabz | $GREP -e '-a*b' 2>/dev/null`" == "x-aabz"; then
+	AC_MSG_RESULT(yes)
+else
+	AC_MSG_RESULT(no)
+	AC_MSG_ERROR([
+Sorry, you have a version of grep which doesn't understand -e.
+$PACKAGE_NAME needs it.  If you have access to a version of grep which does
+understand -e, you can supply its path with the '--with-grep=' option.
+Solaris users can use /usr/xpg4/bin/grep.
+])
+fi
+
+AC_MSG_CHECKING([whether $GREP understand -E])
+if test "`echo aabz | $GREP -E '^a+b' 2>/dev/null`" == "aabz"; then
+	AC_MSG_RESULT(yes)
+else
+	AC_MSG_RESULT(no)
+	AC_MSG_ERROR([
+Sorry, you have a version of grep which doesn't understand -E.
+$PACKAGE_NAME needs it.  If you have access to a version of grep which does
+understand -E, you can supply its path with the '--with-grep=' option.
+Solaris users can use /usr/xpg4/bin/grep.
+])
+fi
+
 dnl Check for sed
 AC_ARG_WITH(sed, AC_HELP_STRING(
     [--with-sed], [name of the sed executable to use]),