仅当目标目录中不存在文件时才下载并移动文件，否则不执行任何操作

Question

我正在尝试通过下载 zip 文件来安装可执行命令 (terraform)，然后使用 Makefile.

将其解压缩到 ~/bin 目录

只有 terraform 文件不存在时，我才想这样做。

根据 GNU Make 文档，我认为我应该使用带有管道 | (https://www.gnu.org/software/make/manual/make.html#Prerequisite-Types) 的 "order-only prerequisite"，尽管我并不完全理解该文档。

我写了下面的目标规则，目的是运行它作为 make install-tf，当文件 ~/bin/terraform 已经存在时，什么都不做并返回。然而，这并没有像预期的那样工作，而且无论文件已经存在，我一直看到正在执行的目标规则的主体。

以下目标有什么问题？
仅当使用 Makefile 命令不存在时，我如何才能安装 terraform？

这是目标：

TERRAFORM_VERSION=0.11.11

install-tf: | ~/bin/terraform
    echo "Installing terraform version ${TERRAFORM_VERSION}"
    mkdir -p ~/tmp/
    wget https://releases.hashicorp.com/terraform/${TERRAFORM_VERSION}/terraform_${TERRAFORM_VERSION}_linux_amd64.zip -P ~/tmp/
    mkdir -p ~/bin/
    unzip ~/tmp/terraform_${TERRAFORM_VERSION}_linux_amd64.zip -d ~/bin/
    echo "Done installing terraform version ${TERRAFORM_VERSION}"
    PATH=~/bin/:$$PATH terraform --version

Answer 1

What's wrong with the following target?

目标是install-tf。 make install-tf 总是运行制作这个的食谱如果不存在 install-tf 这样的文件，则为目标。食谱永远不会创造那个文件。因此食谱将始终是运行.

您需要配方来制作文件 $(HOME)/bin/terraform 当且仅当不存在。对于第一个近似值，这将做到：

生成文件 (1)

TERRAFORM_VERSION=0.11.11

$(HOME)/bin/terraform:
    echo "Installing terraform version ${TERRAFORM_VERSION}"
    mkdir -p $(HOME)/tmp/
    wget https://releases.hashicorp.com/terraform/${TERRAFORM_VERSION}/terraform_${TERRAFORM_VERSION}_linux_amd64.zip -P $(HOME)/tmp/
    mkdir -p $(HOME)/bin/
    unzip ~/tmp/terraform_${TERRAFORM_VERSION}_linux_amd64.zip -d $(HOME)/bin/
    echo "Done installing terraform version ${TERRAFORM_VERSION}"
    PATH=$(HOME)/bin/:$$PATH terraform --version

哪个运行第一次喜欢：

$ make
echo "Installing terraform version 0.11.11"
Installing terraform version 0.11.11
mkdir -p /home/imk/tmp/
wget https://releases.hashicorp.com/terraform/0.11.11/terraform_0.11.11_linux_amd64.zip -P /home/imk/tmp/
--2019-01-29 11:09:11--  https://releases.hashicorp.com/terraform/0.11.11/terraform_0.11.11_linux_amd64.zip
Resolving releases.hashicorp.com (releases.hashicorp.com)... 151.101.17.183, 2a04:4e42:4::439
Connecting to releases.hashicorp.com (releases.hashicorp.com)|151.101.17.183|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 20971661 (20M) [application/zip]
Saving to: ‘/home/imk/tmp/terraform_0.11.11_linux_amd64.zip’

terraform_0.11.11_l 100%[===================>]  20.00M  8.86MB/s    in 2.3s

2019-01-29 11:09:14 (8.86 MB/s) - ‘/home/imk/tmp/terraform_0.11.11_linux_amd64.zip’ saved [20971661/20971661]

mkdir -p /home/imk/bin/
unzip ~/tmp/terraform_0.11.11_linux_amd64.zip -d /home/imk/bin/
Archive:  /home/imk/tmp/terraform_0.11.11_linux_amd64.zip
  inflating: /home/imk/bin/terraform
echo "Done installing terraform version 0.11.11"
Done installing terraform version 0.11.11
PATH=/home/imk/bin/:$PATH terraform --version
Terraform v0.11.11

第二次点赞：

$ make
make: '/home/imk/bin/terraform' is up to date.

稍作改进：

生成文件(2)

TERRAFORM_VERSION := 0.11.11

.PHONY: all clean

all: $(HOME)/bin/terraform

$(HOME)/bin/terraform: | $(HOME)/tmp/ $(HOME)/bin/
    echo "Installing terraform version ${TERRAFORM_VERSION}"
    wget https://releases.hashicorp.com/terraform/${TERRAFORM_VERSION}/terraform_${TERRAFORM_VERSION}_linux_amd64.zip -P $(HOME)/tmp/
    unzip ~/tmp/terraform_${TERRAFORM_VERSION}_linux_amd64.zip -d $(HOME)/bin/
    echo "Done installing terraform version ${TERRAFORM_VERSION}"
    PATH=$(HOME)/bin/:$$PATH terraform --version

$(HOME)/tmp/ $(HOME)/bin/:
    mkdir -p $@

clean:
    $(RM) $(HOME)/bin/terraform

哪个运行像：

$ make clean
rm -f /home/imk/bin/terraform

$ make
echo "Installing terraform version 0.11.11"
Installing terraform version 0.11.11
wget https://releases.hashicorp.com/terraform/0.11.11/terraform_0.11.11_linux_amd64.zip -P /home/imk/tmp/
--2019-01-29 11:38:32--  https://releases.hashicorp.com/terraform/0.11.11/terraform_0.11.11_linux_amd64.zip
Resolving releases.hashicorp.com (releases.hashicorp.com)... 151.101.17.183, 2a04:4e42:4::439
Connecting to releases.hashicorp.com (releases.hashicorp.com)|151.101.17.183|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 20971661 (20M) [application/zip]
Saving to: ‘/home/imk/tmp/terraform_0.11.11_linux_amd64.zip.1’

terraform_0.11.11_l 100%[===================>]  20.00M  8.88MB/s    in 2.3s    

2019-01-29 11:38:34 (8.88 MB/s) - ‘/home/imk/tmp/terraform_0.11.11_linux_amd64.zip.1’ saved [20971661/20971661]

unzip ~/tmp/terraform_0.11.11_linux_amd64.zip -d /home/imk/bin/
Archive:  /home/imk/tmp/terraform_0.11.11_linux_amd64.zip
  inflating: /home/imk/bin/terraform  
echo "Done installing terraform version 0.11.11"
Done installing terraform version 0.11.11
PATH=/home/imk/bin/:$PATH terraform --version
Terraform v0.11.11

$ make
make: Nothing to be done for 'all'.

请注意在以下位置使用仅订单先决条件：

$(HOME)/bin/terraform: | $(HOME)/tmp/ $(HOME)/bin/

也就是说：在考虑目标$(HOME)/bin/terraform是否过时之前，先制作$(HOME)/tmp/和$(HOME)/bin。然后考虑 $(HOME)/bin/terraform 是否过时但不要将 $(HOME)/tmp/ 或 $(HOME)/bin 算作前提条件。

另见 4.6 Phony Targets

仅当目标目录中不存在文件时才下载并移动文件，否则不执行任何操作

Download and move file only if it does not exist on destination directory, otherwise do nothing

makefile

gnu-make