From: Masami Hiramatsu Previous testcase redirects echo-out into /dev/null using "&>" as below echo "trigger-command" >> trigger &> /dev/null But this means redirecting both stdout and stderr into /dev/null because it is same as below echo "trigger-command" >> trigger > /dev/null 2>&1 So ">> trigger" redirects stdout to trigger file, but next "> /dev/null" redirects stdout to /dev/null again and the last "2>/&1" redirects stderr to stdout (/dev/null) This fixes it by "2> /dev/null". And also, since it must fail, add "!" to echo command. Link: http://lkml.kernel.org/r/152292052250.15769.12565292689264162435.stgit@devbox Fixes: f06eec4d0f2c ("selftests: ftrace: Add inter-event hist triggers testcases") Reviewed-by: Tom Zanussi Tested-by: Tom Zanussi Signed-off-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware) --- .../ftrace/test.d/trigger/inter-event/trigger-extended-error-support.tc | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-extended-error-support.tc b/tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-extended-error-support.tc index 786dce7e48be..2aabab363cfb 100644 --- a/tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-extended-error-support.tc +++ b/tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-extended-error-support.tc @@ -29,7 +29,7 @@ do_reset echo "Test extended error support" echo 'hist:keys=pid:ts0=common_timestamp.usecs if comm=="ping"' > events/sched/sched_wakeup/trigger -echo 'hist:keys=pid:ts0=common_timestamp.usecs if comm=="ping"' >> events/sched/sched_wakeup/trigger &>/dev/null +! echo 'hist:keys=pid:ts0=common_timestamp.usecs if comm=="ping"' >> events/sched/sched_wakeup/trigger 2> /dev/null if ! grep -q "ERROR:" events/sched/sched_wakeup/hist; then fail "Failed to generate extended error in histogram" fi -- 2.16.3