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dockerenvironment-variablesdockerfile
Muhammad Tahir Qaiser
Muhammad Tahir Qaiser

Reputation: 708

Correct syntax for concatenating multiple ENV in Dockerfile?

I have 3 ENV Variables, that somehow are dependent on each other.

I found both syntaxes below to be not working and I am not able to find correct sytax also, Can someone please help me ?

ENV_1=/path/
ENV_2="$ENV_1"/dir2
ENV_3="$ENV_2"/dir3


ENV_1=/path/
ENV_2=$ENV_1/dir2
ENV_3=$ENV_2/dir3

Upvotes: 2

Views: 2016

Answers (1)

dejanualex
dejanualex

Reputation: 4328

Environment variables are declared with the ENV statement in Dockerfiles. You can try the following approach

Dockerfile:

FROM alpine

ENV parent=parent_dir
ENV child=child_dir

WORKDIR /tmp

#create nested dir structure in /tmp
RUN mkdir -p $parent\/$child

After you build the image and start the container , you will have the following structure inside the container:

/ # tree /tmp/
/tmp/
└── parent_dir
    └── child_dir

Upvotes: 1

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