如何得知修改某個檔案會被放到root or system folder

使用showcommands

這裡修改了/system/core/init/devices

showcommands告訴你

會被編譯成init檔案
然後安裝到root下

nelsonchung@gps1004:~/myandroid9.1/system/core/init$ mm showcommands
============================================
PLATFORM_VERSION_CODENAME=REL
PLATFORM_VERSION=2.2
TARGET_PRODUCT=imx51_bbg
TARGET_BUILD_VARIANT=eng
TARGET_SIMULATOR=false
TARGET_BUILD_TYPE=release
TARGET_BUILD_APPS=
TARGET_ARCH=arm
HOST_ARCH=x86
HOST_OS=linux
HOST_BUILD_TYPE=release
BUILD_ID=FRF85B
============================================
No private recovery resources for TARGET_DEVICE imx51_bbg
make: Entering directory `/home/nelsonchung/myandroid9.1'
target thumb C: init <= system/core/init/devices.c
prebuilt/linux-x86/toolchain/arm-eabi-4.4.0/bin/arm-eabi-gcc  -I system/core/init   -I out/target/product/imx51_bbg/obj/EXECUTABLES/init_intermediates   -I system/core/include   -I hardware/libhardware/include   -I hardware/libhardware_legacy/include   -I hardware/ril/include   -I dalvik/libnativehelper/include   -I frameworks/base/include   -I frameworks/base/opengl/include   -I external/skia/include   -I out/target/product/imx51_bbg/obj/include   -I bionic/libc/arch-arm/include   -I bionic/libc/include   -I bionic/libstdc++/include   -I bionic/libc/kernel/common   -I bionic/libc/kernel/arch-arm   -I bionic/libm/include   -I bionic/libm/include/arch/arm   -I bionic/libthread_db/include  -c  -fno-exceptions -Wno-multichar -msoft-float -fpic -ffunction-sections -funwind-tables -fstack-protector -fno-short-enums -march=armv7-a -mfloat-abi=softfp -mfpu=neon -include system/core/include/arch/linux-arm/AndroidConfig.h -I system/core/include/arch/linux-arm/ -mthumb-interwork -DANDROID -fmessage-length=0 -W -Wall -Wno-unused -Winit-self -Wpointer-arith -Werror=return-type -Werror=non-virtual-dtor -Werror=address -Werror=sequence-point -DNDEBUG -g -Wstrict-aliasing=2 -finline-functions -fno-inline-functions-called-once -fgcse-after-reload -frerun-cse-after-loop -frename-registers -DNDEBUG -UDEBUG -mthumb -Os -fomit-frame-pointer -fno-strict-aliasing -finline-limit=64       -MD -o out/target/product/imx51_bbg/obj/EXECUTABLES/init_intermediates/devices.o system/core/init/devices.c
target StaticExecutable: init (out/target/product/imx51_bbg/obj/EXECUTABLES/init_intermediates/LINKED/init)
prebuilt/linux-x86/toolchain/arm-eabi-4.4.0/bin/arm-eabi-g++ -nostdlib -Bstatic -Wl,-T,build/core/armelf.x -Wl,--gc-sections -o out/target/product/imx51_bbg/obj/EXECUTABLES/init_intermediates/LINKED/init -Lout/target/product/imx51_bbg/obj/lib out/target/product/imx51_bbg/obj/lib/crtbegin_static.o   -Wl,--no-undefined  -Wl,--fix-cortex-a8         out/target/product/imx51_bbg/obj/EXECUTABLES/init_intermediates/builtins.o out/target/product/imx51_bbg/obj/EXECUTABLES/init_intermediates/init.o out/target/product/imx51_bbg/obj/EXECUTABLES/init_intermediates/devices.o out/target/product/imx51_bbg/obj/EXECUTABLES/init_intermediates/property_service.o out/target/product/imx51_bbg/obj/EXECUTABLES/init_intermediates/util.o out/target/product/imx51_bbg/obj/EXECUTABLES/init_intermediates/parser.o out/target/product/imx51_bbg/obj/EXECUTABLES/init_intermediates/logo.o      out/target/product/imx51_bbg/obj/STATIC_LIBRARIES/liblog_intermediates/liblog.a out/target/product/imx51_bbg/obj/STATIC_LIBRARIES/libcutils_intermediates/libcutils.a out/target/product/imx51_bbg/obj/STATIC_LIBRARIES/libc_intermediates/libc.a  /home/nelsonchung/myandroid9.1/prebuilt/linux-x86/toolchain/arm-eabi-4.4.0/bin/../lib/gcc/arm-eabi/4.4.0/interwork/libgcc.a out/target/product/imx51_bbg/obj/lib/crtend_android.o
target Non-prelinked: init (out/target/product/imx51_bbg/symbols/init)
out/host/linux-x86/bin/acp -fpt out/target/product/imx51_bbg/obj/EXECUTABLES/init_intermediates/LINKED/init out/target/product/imx51_bbg/symbols/init
target Strip: init (out/target/product/imx51_bbg/obj/EXECUTABLES/init_intermediates/init)
out/host/linux-x86/bin/soslim --strip --shady --quiet out/target/product/imx51_bbg/symbols/init --outfile out/target/product/imx51_bbg/obj/EXECUTABLES/init_intermediates/init
Install: out/target/product/imx51_bbg/root/init
out/host/linux-x86/bin/acp -fpt out/target/product/imx51_bbg/obj/EXECUTABLES/init_intermediates/init out/target/product/imx51_bbg/root/init
Copy: out/target/product/imx51_bbg/root/init.rc
out/host/linux-x86/bin/acp -fpt device/fsl/imx5x/init.rc out/target/product/imx51_bbg/root/init.rc
make: Leaving directory `/home/nelsonchung/myandroid9.1'