请问一下楼主，按照你的教程。
mmm external/test/
然后提示：
============================================
PLATFORM_VERSION_CODENAME=REL
PLATFORM_VERSION=4.4.2
TARGET_PRODUCT=mars_a31s
TARGET_BUILD_VARIANT=eng
TARGET_BUILD_TYPE=release
TARGET_BUILD_APPS=
TARGET_ARCH=arm
TARGET_ARCH_VARIANT=armv7-a-neon
TARGET_CPU_VARIANT=cortex-a7
HOST_ARCH=x86
HOST_OS=linux
HOST_OS_EXTRA=Linux-3.13.0-71-generic-x86_64-with-Ubuntu-14.04-trusty
HOST_BUILD_TYPE=release
BUILD_ID=KOT49H
OUT_DIR=out
============================================
/bin/bash: out/target/product/mars-a31s/previous_build_config.mk: Permission denied
touch: cannot touch ‘out/target/common/obj/APPS/current_overlays.txt’: Permission denied
/bin/bash: out/target/common/obj/APPS/current_packages.txt: Permission denied
Traceback (most recent call last):
File "build/tools/diff_package_overlays.py", line 91, in <module>
main(sys.argv)
File "build/tools/diff_package_overlays.py", line 60, in main
current_overlays = load_overlay_config(argv[2])
File "build/tools/diff_package_overlays.py", line 49, in load_overlay_config
f = open(filename)
IOError: [Errno 2] No such file or directory: 'out/target/common/obj/APPS/current_overlays.txt'
mv: cannot stat ‘out/target/common/obj/APPS/current_overlays.txt’: No such file or directory
No private recovery resources for TARGET_DEVICE mars-a31s
make: Entering directory `/home/idata/work/BPI-M2-Android4.4/android'
Import includes file: out/target/product/mars-a31s/obj/EXECUTABLES/test_intermediates/import_includes
mkdir: cannot create directory ‘out/target/product/mars-a31s/obj/EXECUTABLES/test_intermediates/’: Permission denied
make: *** [out/target/product/mars-a31s/obj/EXECUTABLES/test_intermediates/import_includes] Error 1
make: Leaving directory `/home/idata/work/BPI-M2-Android4.4/android'
提示：Permission denied
所以我改成 sudo mmm external/test/
但又提示找不到命令，请问这是什么情况？ | 
