Makefile变量作为先决条件 [英] Makefile variable as prerequisite

问题描述

在Makefile中，deploy配方需要将环境变量ENV设置为正确执行自身，而其他情况不在乎，例如:

In a Makefile, a deploy recipe needs a environment variable ENV to be set to properly execute itself, whereas others don't care, eg:

ENV = 

.PHONY: deploy hello

deploy:
    rsync . $(ENV).example.com:/var/www/myapp/

hello:
    echo "I don't care about ENV, just saying hello!"

如何确保设置此变量，例如:有没有一种方法可以将该makefile变量声明为部署配方的先决条件，例如:

How can I make sure this variable is set, eg: is there a way to declare this makefile variable as a prerequisite of the deploy recipe, like:

deploy: make-sure-ENV-variable-is-set

?

谢谢.

推荐答案

如果未定义ENV并且需要某些内容(无论如何，在GNUMake中)，这将导致致命错误.

This will cause a fatal error if ENV is undefined and something needs it (in GNUMake, anyway).

.PHONY: deploy check-env

deploy: check-env
	...

other-thing-that-needs-env: check-env
	...

check-env:
ifndef ENV
	$(error ENV is undefined)
endif

(请注意，ifndef和endif不会缩进-它们控制哪些内容"sees" ，在运行Makefile之前生效."$(error)用制表符缩进，以便仅在规则的上下文中运行."

(Note that ifndef and endif are not indented - they control what make "sees", taking effect before the Makefile is run. "$(error" is indented with a tab so that it only runs in the context of the rule.)

这篇关于Makefile变量作为先决条件的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！