GNU make manual 翻译( 一百二十五)
继续翻译
Here is the pattern rule to generate a file of prerequisites (i.e., a makefile) called `NAME.d' from a C source file called `NAME.c': %.d: %.c @set -e; rm -f $@; \ $(CC) -M $(CPPFLAGS) $< > $@.$$$$; \ sed 's,\($*\)\.o[ :]*,\1.o $@ : ,g' < $@.$$$$ > $@; \ rm -f $@.$$$$ *Note Pattern Rules::, for information on defining pattern rules. The `-e' flag to the shell causes it to exit immediately if the `$(CC)' command (or any other command) fails (exits with a nonzero status). With the GNU C compiler, you may wish to use the `-MM' flag instead of `-M'. This omits prerequisites on system header files. *Note Options Controlling the Preprocessor: (gcc.info)Preprocessor Options, for details. The purpose of the `sed' command is to translate (for example): main.o : main.c defs.h into: main.o main.d : main.c defs.h This makes each `.d' file depend on all the source and header files that the corresponding `.o' file depends on. `make' then knows it must regenerate the prerequisites whenever any of the source or header files changes.
下面是一个模式规则,用来生成一个前提条件文件(例如一个 makefile) ,此文件名为 NAME.d ,是从名为 NAME.c 的源文件而来:
%.d: %.c
@set -e; rm -f $@; \
$(CC) -M $(CPPFLAGS) $< > $@.$$$$; \
sed 's,\($*\)\.o[ :]*,\1.o $@ : ,g' < $@.$$$$ > $@; \
rm -f $@.$$$$
关于 定义 模式规则,参见 *Note Pattern Rules::。
-e 标志是的如果 $(CC) (或其他指令)一旦失败(以非0值退出),shell 立即退出。
对GNU C 编译器而言,你可期望用 -MM 标志来代替 -M 标志,这省略了系统头文件部分的前提条件。 细节参见 *Note Options Controlling the Preprocessor: (gcc.info) Preprocessor Options.
The purpose of the `sed' command is to translate (for example):
sed 命令的目的是翻译(例如):
把 main.o : main.c defs.h
翻译成:
main.o main.d : main.c defs.h
这使得 每个 .d 文件依赖于所有的.o 文件依赖的 源文件和头文件。make 这样就会知道,当源文件或者头文件变化时,它必须重新生成前提条件。
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