的Makefile文件功能演示错误

Question

我一直想把文件功能的结果，在Makefile中为我演示用小makefile文件为：

CMD = cat 

OBJECTS = Makefile Makefile-filter-func 

program : $(OBJECTS) 
     $(file >$@.in) $(foreach O,$^,$(file >>$@.in,$O)) 
     @echo The file has been created. 
all : 
     $(CMD) $(CMDFLAGS) @$@.in 
     @echo The file contents are printed. 
     @rm $@.in 
     @echo The file removed. 

我想用ls命令来查看文件的文件名，但这makefile有以下错误：

Makefile-file-func:7: *** recipe commences before first target. Stop. 

我在哪里出错。

Answer 1

的指针答案可以在源代码中找到make（版本3.82），该文件read.c在：

989  /* This line starts with a tab but was not caught above because there 
990   was no preceding target, and the line might have been usable as a 
991   variable definition. But now we know it is definitely lossage. */ 
992  if (line[0] == cmd_prefix) 
993  O (fatal, fstart, _("recipe commences before first target")); 

有了这些信息，可以通过插入空格，重现您的问题正确的位置。在下面的代码，~表示空间和<TAB>表示TAB：

program : $(OBJECTS) 
~~~~~~~~$(file >$@.in) $(foreach O,$^,$(file >>$@.in,$O)) 
<TAB> @echo The file has been created. 

由于空格和制表符得到你的问题失去了，这是一个有点很难看到，如果这正是你的情况，以及虽然。

请注意，食谱通常应该以TAB开头。