Re: [Libguestfs] [PATCH nbdinfo v2 3/3] copy: Print debug information with human sizes

On Mon, Sep 20, 2021 at 06:32:29PM +0200, Laszlo Ersek wrote: >> +++ b/copy/test-verbose.sh >> @@ -28,11 +28,11 @@ requires nbdkit --version >> file=test-verbose.out >> cleanup_fn rm -f $file >> >> -$VG nbdcopy -v -- [ nbdkit null ] null: 2>$file >> +$VG nbdcopy -v -- [ nbdkit memory 1M ] null: 2>$file > > (1) I don't understand this change. Why do we replace "null" with > "memory 1M"? > > (Side question that I've been meaning to ask: what is this "$VG" magic?) Answering just the side question: When LIBNBD_VALGRIND is set to 1 in the environment, then $VG is set in run.in to an invocation of valgrind, optionally further wrapped by an invocation of libtool to see through any libtool wrapper script. Otherwise $VG is empty, and you run the real binary without any outer wrappers. It's actually a clever way of checking memory usage issues during 'make check-valgrind' while probing the real binary rather than accidentally running valgrind on a shell script.