Building application "hello-world" for "stm32f4discovery" with MCU "stm32f4".

"make" -C /data/riotbuild/riotbase/boards/stm32f4discovery
"make" -C /data/riotbuild/riotbase/core
"make" -C /data/riotbuild/riotbase/cpu/stm32f4
"make" -C /data/riotbuild/riotbase/cpu/cortexm_common
"make" -C /data/riotbuild/riotbase/cpu/cortexm_common/periph
"make" -C /data/riotbuild/riotbase/cpu/stm32_common
"make" -C /data/riotbuild/riotbase/cpu/stm32_common/periph
"make" -C /data/riotbuild/riotbase/cpu/stm32f4/periph
"make" -C /data/riotbuild/riotbase/drivers
"make" -C /data/riotbuild/riotbase/drivers/periph_common
"make" -C /data/riotbuild/riotbase/sys
"make" -C /data/riotbuild/riotbase/sys/auto_init
"make" -C /data/riotbuild/riotbase/sys/isrpipe
"make" -C /data/riotbuild/riotbase/sys/newlib_syscalls_default
"make" -C /data/riotbuild/riotbase/sys/pm_layered
"make" -C /data/riotbuild/riotbase/sys/stdio_uart
"make" -C /data/riotbuild/riotbase/sys/tsrb
   text    data     bss     dec     hex filename
   8756     140    2620   11516    2cfc /data/riotbuild/riotbase/examples/hello-world/bin/stm32f4discovery/hello-world.elf
/home/huaxing/oproj/riot/RIOT-2019.04/dist/tools/openocd/openocd.sh flash /home/huaxing/oproj/riot/RIOT-2019.04/examples/hello-world/bin/stm32f4discovery/hello-world.elf
 Flashing Target
sh: 1: openocd: not found
/home/huaxing/oproj/riot/RIOT-2019.04/examples/hello-world/../../Makefile.include:538: recipe for target 'flash' failed
make: *** [flash] Error 127