Messages in this thread | ![/](/images/icornerl.gif) | | From | Andrii Nakryiko <> | Date | Mon, 16 Sep 2019 15:01:52 -0700 | Subject | Re: [PATCH v3 bpf-next 01/14] samples: bpf: makefile: fix HDR_PROBE "echo" |
| |
On Mon, Sep 16, 2019 at 2:35 PM Andreas Schwab <schwab@linux-m68k.org> wrote: > > On Sep 16 2019, Andrii Nakryiko <andrii.nakryiko@gmail.com> wrote: > > > On Mon, Sep 16, 2019 at 3:59 AM Ivan Khoronzhuk > > <ivan.khoronzhuk@linaro.org> wrote: > >> > >> echo should be replaced with echo -e to handle '\n' correctly, but > >> instead, replace it with printf as some systems can't handle echo -e. > >> > >> Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org> > >> --- > >> samples/bpf/Makefile | 2 +- > >> 1 file changed, 1 insertion(+), 1 deletion(-) > >> > >> diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile > >> index 1d9be26b4edd..f50ca852c2a8 100644 > >> --- a/samples/bpf/Makefile > >> +++ b/samples/bpf/Makefile > >> @@ -201,7 +201,7 @@ endif > >> > >> # Don't evaluate probes and warnings if we need to run make recursively > >> ifneq ($(src),) > >> -HDR_PROBE := $(shell echo "\#include <linux/types.h>\n struct list_head { int a; }; int main() { return 0; }" | \ > >> +HDR_PROBE := $(shell printf "\#include <linux/types.h>\n struct list_head { int a; }; int main() { return 0; }" | \ > > > > printf change is fine, but I'm confused about \# at the beginning of > > the string. > > From the NEWS of make 4.3: > > * WARNING: Backward-incompatibility! > Number signs (#) appearing inside a macro reference or function invocation > no longer introduce comments and should not be escaped with backslashes: > thus a call such as: > foo := $(shell echo '#') > is legal. Previously the number sign needed to be escaped, for example: > foo := $(shell echo '\#') > Now this latter will resolve to "\#". If you want to write makefiles > portable to both versions, assign the number sign to a variable: > H := \# > foo := $(shell echo '$H') > This was claimed to be fixed in 3.81, but wasn't, for some reason. > To detect this change search for 'nocomment' in the .FEATURES variable. > > Andreas.
Oh, subtle... Thanks for explaining!
> > -- > Andreas Schwab, schwab@linux-m68k.org > GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510 2552 DF73 E780 A9DA AEC1 > "And now for something completely different."
| ![\](/images/icornerr.gif) |