configure.ac |   51 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)

--- quilt.orig/configure.ac	2005-09-18 13:19:43.000000000 +0200
+++ quilt/configure.ac	2005-09-18 13:19:47.000000000 +0200
@@ -55,6 +55,57 @@
 
 QUILT_COMPAT_PROG_PATH(PERL, perl, [perl perl5])
 QUILT_COMPAT_PROG_PATH(GREP, grep)
+
+AC_MSG_CHECKING([whether $GREP -q works])
+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 -v works])
+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 -e works])
+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 -E works])
+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
+
 QUILT_COMPAT_PROG_PATH(TAIL, tail)
 
 # Solaris' /usr/bin/tail doesn't understand -n.