定义变量时触发 ifndef 变量

Question

为什么，当我运行 make run-e2e-docker 是ifndef 激活？该变量应该被设置，但 make 决定它不是。运行的 echo 命令可用。如果我删除 ifndef，并且运行 make 它会打印变量。

run-e2e:
ifndef environment
$(error "You can't run run-e2e directly, choose one of the run-e2e-* tasks ${environment}")
endif
    @echo extra_profiles=${extra_profiles}
    @echo environment=${environment}

run-e2e-docker: override extra_profiles = docker-e2e,dev-performance
run-e2e-docker: override environment = docker
run-e2e-docker: run-e2e

Answer 1

您不能在上下文中使用 make 条件语句。当您显然在思考时，它们不会被评估。但是您可以使用 shell 条件，而不是：

run-e2e:
    @if [ -z "$(environment)" ]; then \
        echo "You can't run run-e2e directly, choose one of the run-e2e-* tasks"; \
        exit 1; \
    fi
    @echo extra_profiles=${extra_profiles}
    @echo environment=${environment}

GNU Make 手册说...

Conditionals control what make actually “sees” in the makefile, so they cannot be used to control recipes at the time of execution.

https://www.gnu.org/software/make/manual/html_node/Conditionals.html

定义变量时触发 ifndef 变量

ifndef variable triggers when variable is defined

makefile

gnu-make