测试makefile中是否存在目录 [英] Test whether a directory exists inside a makefile

问题描述

@Grundlefleck在他的答案中解释了如何检查目录是否存在.我尝试了一些在makefile中使用它的方法，如下所示:

In his answer @Grundlefleck explains how to check whether a directory exists or not. I tried some to use this inside a makefile as follow:

foo.bak: foo.bar
    echo "foo"
    if [ -d "~/Dropbox" ]; then
        echo "Dir exists"
    fi

运行make foo.bak(假设存在foo.bar)会产生以下错误:

Running make foo.bak (given that foo.bar exists) yields the following error:

echo "foo"
foo
if [ -d "~/Dropbox" ]; then
/bin/sh: -c: line 1: syntax error: unexpected end of file
make: *** [foo.bak] Error 2

我所做的解决方法是使用一个独立的bash脚本来实现测试，然后我从makefile调用了该脚本.但是，这听起来很麻烦.有没有更好的方法可以检查makefile中是否存在目录?

The workaround I made was to have a standalone bash script where the test is implemented and I called the script from the makefile. This, however, sounds very cumbersome. Is there a nicer way to check whether a directory exists from within a makefile?

推荐答案

如果使用shell命令，则使命令必须在一行中，或者使用反斜杠进行行扩展时在多行中.因此，这种方法将起作用:

Make commands, if a shell command, must be in one line, or be on multiple lines using a backslash for line extension. So, this approach will work:

foo.bak: foo.bar
    echo "foo"
    if [ -d "~/Dropbox" ]; then echo "Dir exists"; fi

或

foo.bak: foo.bar
    echo "foo"
    if [ -d "~/Dropbox" ]; then \
        echo "Dir exists"; \
    fi

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