第二个最重要的答案是ifeq，但是，它没有提到这些必须与目标名称处于同一级别，例如，仅在当前不存在的情况下下载文件，才可以使用以下代码:

The second top answer mentions ifeq, however, it fails to mention that these must be on the same level as the name of the target, e.g., to download a file only if it doesn't currently exist, the following code could be used:

download:
ifeq (,$(wildcard ./glob.c))
    curl … -o glob.c
endif