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記錄makefile一些小地方

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item note
20160917 第一版
20170208 了解makefile錯誤停止

目錄

結論

make預設若遇到錯誤(即make fail 或shell status($?))就會停止

若使用pushd或if(等一連串的shell 指令，使得status被最後指令覆蓋)
因此抓不到錯誤的情況，一直執行到最後
在使用pushd或if等裡面的程序需要自已判斷，若遇到錯誤需要停止

了解makefile錯誤停止

來源：Testing the Compilation of a Program
Normally, when an error happens in executing a shell command, make gives up immediately, returning a nonzero status.

由上面可以知預設make是遇到錯誤就會停止
但若遇到下列例子(return code被其寫指令變成0)，這時make得到就不是fail，因此就不會停止

測試make fail

  • make fail
    由於沒有存在/root/file-1，因此停止(即沒有打印t22)
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    root@1cc5d8f59283:[~]$ cat Makefile 
    all:
            @echo "t11"
            @ls -l /root/file-1
            @echo "t22"
    root@1cc5d8f59283:[~]$ make
    t11
    ls: cannot access /root/file-1: No such file or directory
    make: *** [all] Error 2

makefile 使用pushd及popd

  • 錯誤抓不到
    即回傳到make的status被popd取代
    因此若為fail，則還是沒有被抓到(即有打印t22)

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    root@1cc5d8f59283:[~]$ cat Makefile 
    all:
            @echo "t11"
            @pushd /root; ls -l file-1;popd
            @echo "t22"

    root@1cc5d8f59283:[~]$ make
    t11
    ~ ~
    ls: cannot access file-1: No such file or directory
    ~
    t22

  • 修正: 錯誤抓不到
    增加判斷錯誤之後離開

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    root@1cc5d8f59283:[~]$ cat Makefile 
    all:
            @echo "t11"
            @pushd /root; ls -l file-1 || exit;popd
            @echo "t22"

    root@1cc5d8f59283:[~]$ make
    t11
    ~ ~
    ls: cannot access file-1: No such file or directory
    make: *** [all] Error 2

makefiel 使用 if

  • 錯誤抓的到
    if最後指令 有產生的錯誤，因此抓的到

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    root@1cc5d8f59283:[~]$ cat Makefile 
    all:
            @echo "t11"
            @if [ -d /root ]; then          \
                    ls -l /root/file-1;     \
            fi
            @echo "t22"

    root@1cc5d8f59283:[~]$ make
    t11
    ls: cannot access /root/file-1: No such file or directory
    make: *** [all] Error 2

  • 錯誤抓不到
    增加判斷錯誤之後離開
    if最後指令 沒有產生的錯誤，因此不抓到

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    root@1cc5d8f59283:[~]$ cat Makefile 
    all:
            @echo "t11"
            @if [ -d /root ]; then          \
                    ls -l /root/file-1;     \
                    ls -d /root;            \
            fi
            @echo "t22"

    root@1cc5d8f59283:[~]$ make
    t11
    ls: cannot access /root/file-1: No such file or directory
    /root
    t22

  • 修正: 錯誤抓不到

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    root@1cc5d8f59283:[~]$ cat Makefile 
    all:
            @echo "t11"
            @if [ -d /root ]; then          \
                    ls -l /root/file-1 || exit;     \
                    ls -d /root;            \
            fi
            @echo "t22"

    root@1cc5d8f59283:[~]$ make
    t11
    ls: cannot access /root/file-1: No such file or directory
    make: *** [all] Error 2

make status

來源：[How to Run make]

The exit status of make is always one of three values:

  • 0
    The exit status is zero if make is successful.

  • 2
    The exit status is two if make encounters any errors. It will print messages describing the particular errors.

  • 1
    The exit status is one if you use the ‘-q’ flag and make determines that some target is not already up to date. See Instead of Executing Recipes.

Makefile

如何停止當gcc fail

  • 當make nvr時gcc fail，後的.c檔是不會再compile
    因為makefile預設,為遇到fail則停止，若想不停止則需要使用make -k

  • 但此時還會執行make -C ipserver及後續的其它操作

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    all:
    	make -C $(GIT_TOP_DIR)/tools/host chk_host_rootfs
    	make clean
    	pushd nvr; make ; popd
    	make -C ipserver
    	make release

  • 改成下例，則不會有後續的其它操作(如make -C ipserver)

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    all:
    	make -C $(GIT_TOP_DIR)/tools/host chk_host_rootfs
    	make clean
    	pushd nvr; make || exit; popd
    	make -C ipserver || exit
    	make release

參考