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5.2 Recipe Echoing ================== Normally `make' prints each line of the recipe before it is executed. We call this "echoing" because it gives the appearance that you are typing the lines yourself. When a line starts with `@', the echoing of that line is suppressed. The `@' is discarded before the line is passed to the shell. Typically you would use this for a command whose only effect is to print something, such as an `echo' command to indicate progress through the makefile: @echo About to make distribution files When `make' is given the flag `-n' or `--just-print' it only echoes most recipes, without executing them. *Note Summary of Options: Options Summary. In this case even the recipe lines starting with `@' are printed. This flag is useful for finding out which recipes `make' thinks are necessary without actually doing them. The `-s' or `--silent' flag to `make' prevents all echoing, as if all recipes started with `@'. A rule in the makefile for the special target `.SILENT' without prerequisites has the same effect (*note Special Built-in Target Names: Special Targets.). `.SILENT' is essentially obsolete since `@' is more flexible.
5.2 片段显示
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通常 make 在执行片段的一行之前，打印出此行。我们成为显示。因为它给出你自己输入的原样。当一行开始于@, 对此行的显示被禁止。在此行被传递给shell的时候，@被去掉。典型地，你可以用这个命令来单纯打印一些东西，比如用 echo 命令来显示 makefile 的进度，例如：
@echo About to make distribution files
当运行 make 时，给定了标志 -n 或者 --just-print ，它只显示所有的片段，而不执行它们。*Note Summary of Options: Opitons Summary. 在这种场合下既使是开始于 @ 的行也会被显示。 当想要找出 make 认为哪个片段应当执行而不必执行的时候，是有用的。
make 的 -s 或者 --silent 标志，禁止所有的显示，就好像素有的片段都开始于@一样。一个带有特殊目的 没有前提条件的.SLIENT 的makefile 也可以达成同样效果(*note Special Built-bin Target Names: Sepcial Targets.)。.SLIENT 更加的老式应当废弃，因为 @更加灵活。
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