kbuild: Improve portability of some sed invocations
* Use BREs where EREs aren't necessary.
* Pass -E instead of -r to use EREs. This will be standardized in the
next POSIX revision[0]. GNU sed supports this since 4.2 (May 2009),
and busybox since 1.22.0 (Jan 2014).
* Use the [:space:] character class instead of ` \t` in bracket
expressions. In bracket expressions, POSIX says that <backslash> loses
its special meaning, so a conforming implementation cannot expand \t
to <tab>[1].
* In BREs, use interval expressions (\{n,m\}) instead of non-standard
features like \+ and \?.
* Use a loop instead of -s flag.
There are still plenty of other cases of non-standard sed invocations
(use of ERE features in BREs, in-place editing), but this fixes some
core ones.
[0] http://austingroupbugs.net/view.php?id=528
[1] http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap09.html#tag_09_03_05
Signed-off-by: Michael Forney <forney@google.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 4f2b25d..fff7709 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -314,7 +314,7 @@
# List module undefined symbols (or empty line if not enabled)
ifdef CONFIG_TRIM_UNUSED_KSYMS
-cmd_undef_syms = $(NM) $@ | sed -n 's/^ \+U //p' | xargs echo
+cmd_undef_syms = $(NM) $@ | sed -n 's/^ *U //p' | xargs echo
else
cmd_undef_syms = echo
endif
