Hi Liu,
On Wed, 29 Apr 2020 15:13:20 +0800
Liu Yiding <yidingx.liu@xxxxxxxxx> wrote:
> Hi, all.
>
>
> I met a funny error when i run kprobe_syntax_errors
>
> ```
>
> root@vm-snb-35
> /usr/src/linux-selftests-x86_64-rhel-7.6-kselftests-ae83d0b416db002fe95601e7f97f64b59514d936/tools/testing/selftests/ftrace#
> ./ftracetest -vvv test.d/kprobe/kprobe_syntax_errors.tc [snip] + expr 13
> + 0 + test 13 -eq 13 + echo p:kprobes/testevent _do_fork abcd=\1 sh:
> echo: I/O error
>
> ```
>
> This error only happend on dash, use bash run this test is ok.
>
> backslash ('\1') will be transferred into empty in dash.
Oops, good catch! I found that came from the built-in echo command
behavior.
Bash's echo doesn't interpret the backslash escape, but dash's
POSIX-compliant echo does.
----<dash>----
$ a='\1'
$ b=`echo $a`
$ test "$a" = "$b" && echo "same!" || echo "different"
different
----<bash>----
$ a='\1'
$ b=`echo $a`
$ test "$a" = "$b" && echo "same!" || echo "different"
same!
OK, I'll fix it.
Thank you!
--
Masami Hiramatsu <mhiramat@xxxxxxxxxx>
