sh GCCのsysrootオプションについて调べてみたref：http：//qiita.com/maskedw/items/e73df32007934e75d9e3

Posted 2021-05-07

    % cd /usr/lib/gcc-cross/arm-linux-gnueabi/5/../../../../arm-linux-gnueabi/include
    % find . -name "stdio.h" | sed -e 's/^\.\///g'
    bits/stdio.h
    stdio.h

    % arm-linux-gnueabi-gcc -v --sysroot=/dammy -o hello hello.c
    Using built-in specs.
    COLLECT_GCC=arm-linux-gnueabi-gcc
    COLLECT_LTO_WRAPPER=/usr/lib/gcc-cross/arm-linux-gnueabi/5/lto-wrapper
    Target: arm-linux-gnueabi

    ignoring nonexistent directory "/dammy/usr/local/include/arm-linux-gnueabi"
    ignoring nonexistent directory "/dammy/usr/include/arm-linux-gnueabi"
    ignoring nonexistent directory "/dammy/usr/include"
    #include "..." search starts here:
    #include <...> search starts here:
     /usr/lib/gcc-cross/arm-linux-gnueabi/5/include
     /usr/lib/gcc-cross/arm-linux-gnueabi/5/include-fixed
     /usr/lib/gcc-cross/arm-linux-gnueabi/5/../../../../arm-linux-gnueabi/include
    End of search list.

    % gcc -v --sysroot=/dammy -o hello hello.c
    Using built-in specs.
    COLLECT_GCC=gcc
    COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/5/lto-wrapper
    Target: x86_64-linux-gnu
    ...
    ignoring nonexistent directory "/dammy/usr/local/include/x86_64-linux-gnu"
    ignoring nonexistent directory "/dammy/usr/local/include"
    ignoring nonexistent directory "/usr/lib/gcc/x86_64-linux-gnu/5/../../../../x86_64-linux-gnu/include"
    ignoring nonexistent directory "/dammy/usr/include/x86_64-linux-gnu"
    ignoring nonexistent directory "/dammy/usr/include"
    #include "..." search starts here:
    #include <...> search starts here:
     /usr/lib/gcc/x86_64-linux-gnu/5/include
     /usr/lib/gcc/x86_64-linux-gnu/5/include-fixed
    End of search list.
    ...
    hello.c:1:19: fatal error: stdio.h: そのようなファイルやディレクトリはありません
    compilation terminated.

    % arm-linux-gnueabi-gcc --sysroot=/dammy -o hello hello.c

    % gcc --sysroot=/dammy -o hello hello.c
    hello.c:1:19: fatal error: stdio.h: そのようなファイルやディレクトリはありません
    compilation terminated.

    # OS
    % lsb_release -a
    No LSB modules are available.
    Distributor ID: Ubuntu
    Description:    Ubuntu 16.04.1 LTS
    Release:        16.04
    Codename:       xenial

    # ホストPC GCCのバージョン 
    % gcc --version
    gcc (Ubuntu 5.4.0-6ubuntu1~16.04.4) 5.4.0 20160609

    # クロス GCCのインストール
    % sudo apt-get install -y gcc-arm-linux-gnueabi

    # クロス GCCのバージョン
    % arm-linux-gnueabi-gcc --version
    arm-linux-gnueabi-gcc (Ubuntu/Linaro 5.4.0-6ubuntu1~16.04.4) 5.4.0 20160609