如何在 Dockerfile 中编写多行命令，同时保留新行? [英] How to write commands with multiple lines in Dockerfile while preserving the new lines?

问题描述

我想在 Dockerfile 中编写以下 RUN 命令.但是，docker 并没有保留新行.

I want to write the following RUN command in the Dockerfile. But, docker is not preserving the new lines.

RUN echo "[repo] 
name            = YUM Repository 
baseurl         = https://example.com/packages/ 
enabled         = 1 
gpgcheck        = 0" > /etc/yum.repos.d/Repo.repoxyz

我知道每行末尾的 会转义新行.但是，有什么办法可以写多行来保留新行?

I know that at the end of each line escapes the new line. But, is there any way that I can write multiple lines preserving the new line?

推荐答案

您可以使用所谓的ANSI-C 引用"与 $'...'.它最初是 ksh93 功能，但现在可以在 bash、zsh、mksh、FreeBSD sh 和 busybox 的 ash 中使用(但仅当它使用 ENABLE_ASH_BASH_COMPAT 编译时).

You can use what is called "ANSI-C quoting" with $'...'. It was originally a ksh93 feature but it is now available in bash, zsh, mksh, FreeBSD sh and in busybox's ash (but only when it is compiled with ENABLE_ASH_BASH_COMPAT).

作为 RUN 使用 /bin/sh 作为外壳默认你需要先使用SHELL指令切换到bash之类的东西.

As RUN uses /bin/sh as shell by default you are required to switch to something like bash first by using the SHELL instruction.

以 $' 开始您的命令，以 ' 结束并使用 作为换行符，如下所示:

Start your command with $', end it with ' and use for newlines, like this:

SHELL ["/bin/bash", "-c"]

RUN echo $'[repo] 

name            = YUM Repository 

baseurl         = https://example.com/packages/ 

enabled         = 1 

gpgcheck        = 0' > /etc/yum.repos.d/Repo.repoxyz

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