Am 08.08.2017 um 16:29 hat Eric Blake geschrieben: > On 08/08/2017 08:54 AM, Kevin Wolf wrote: > > Am 03.07.2017 um 20:09 hat Eric Blake geschrieben: > >> POSIX says that backslashes in the arguments to 'echo', as well as > >> any use of 'echo -n' and 'echo -e', are non-portable; it recommends > >> people should favor 'printf' instead. This is definitely true where > >> we do not control which shell is running (such as in makefile snippets > >> or in documentation examples). But even for scripts where we > >> require bash (and therefore, where echo does what we want by default), > >> it is still possible to use 'shopt -s xpg_echo' to change bash's > >> behavior of echo. And setting a good example never hurts when we are > >> not sure if a snippet will be copied from a bash-only script to a > >> general shell script (although I don't change the use of non-portable > >> \e for ESC when we know the running shell is bash). > >> > > >> +++ b/tests/multiboot/run_test.sh > >> @@ -26,7 +26,7 @@ run_qemu() { > >> local kernel=$1 > >> shift > >> > >> - echo -e "\n\n=== Running test case: $kernel $@ ===\n" >> test.log > >> + printf %b "\n\n=== Running test case: $kernel $@ ===\n\n" >> test.log > >> > >> $QEMU \ > >> -kernel $kernel \ > > > > Not completely sure why, but this broke the test with whitespace changes > > like this: > > > > -=== Running test case: mmap.elf -m 1.1M === > > +=== Running test case: mmap.elf -m1.1M === > > I guess that means I'm not regularly running tests/multiboot? Is it not > part of 'make check' or qemu-iotests?
The problem is that it needs an i386 compiler to build the test kernels (and qemu-system-i386 or qemu-system-x86_64 binaries to execute them). I guess we could check these conditions, though, and skip the test if we can't produce i386 binaries. > Ah, I see the problem, and it's insidious. We're using "...$@...", but > want to be using "...$*...". $@ causes multiple arguments to be passed, > but printf %b is not concatenating those arguments; while $* uses only a > single argument. We didn't notice it with echo -e, because echo inserts > a space between multiple arguments, just as you'd get a space with $*. The thing that completely confused me here is that printf doesn't just ignore additional arguments as I would have expected, but just starts over with the format string, so that it does kind of work with multiple arguments and fails only subtly. Kevin
signature.asc
Description: PGP signature