<p>I assume you have a copy-paste issue. The right package name is <code>build-essential</code>. And if you want to split a RUN statement over several lines, you will have to use backslash for line continuation.</p>

<p>All that leading to something along the lines of:</p>

<pre><code>RUN apt-get update -yqq; apt-get -yqq install ruby ruby-dev \
          build-essential redis-tools
</code></pre>

<p>As a personal suggestion, when you have several commands to run, it is usually better to join them using <code>&amp;&amp;</code> rather than <code>;</code> since you want the build to fail if <em>either</em> command is failing.</p>

<pre><code>RUN apt-get update -yqq &amp;&amp; apt-get -yqq install ruby ruby-dev \
          build-essential redis-tools
</code></pre>

CC BY-SA 4.0
2019-02-05T12:45:31.247Z
2019-02-05T12:45:31.247Z
Sylvain Leroux
<p>this is my dockerfile ; </p>

<pre><code>FROM ubuntu:16.04
MAINTAINER James Turnbull "james@example.com"
ENV REFRESHED_AT 2016-06-01
RUN apt-get update -yqq; apt-get -yqq install ruby ruby-dev build 
  -essential redis-tools

RUN gem install --no-rdoc --no-ri sinatra json redis
RUN mkdir -p /opt/webapp
EXPOSE 4567


CMD [ "/opt/webapp/bin/webapp" ]
</code></pre>

<p>and this is how i ran it : </p>

<blockquote>
  <p>docker build -t jamtur01/sinatra .</p>
</blockquote>

<p>however i get this error in regard to  -essential </p>

<blockquote>
  <p>Dockerfile parse error line 5: unknown instruction: -ESSENTIAL</p>
</blockquote>

<p>i am not clear what i have done wrong. is there an equivalent for -essential </p>

<dockerfile>
Dockerfile parse error line 5: unknown instruction: -ESSENTIAL
theSeeker
# Dockerfile parse error line 5: unknown instruction: -ESSENTIAL

(Asked by: username_0 on 2019-02-05)

this is my dockerfile ; 
FROM ubuntu:16.04
MAINTAINER James Turnbull "james@example.com"
ENV REFRESHED_AT 2016-06-01
RUN apt-get update -yqq; apt-get -yqq install ruby ruby-dev build 
  -essential redis-tools

RUN gem install --no-rdoc --no-ri sinatra json redis
RUN mkdir -p /opt/webapp
EXPOSE 4567


CMD [ "/opt/webapp/bin/webapp" ]

and this is how i ran it : 

docker build -t jamtur01/sinatra .

however i get this error in regard to  -essential 

Dockerfile parse error line 5: unknown instruction: -ESSENTIAL

i am not clear what i have done wrong. is there an equivalent for -essential

**Tags:** dockerfile


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## 1 answers

### Answer by username_1 on 2019-02-05. Score: 3 | Accepted answer

I assume you have a copy-paste issue. The right package name is build-essential. And if you want to split a RUN statement over several lines, you will have to use backslash for line continuation.
All that leading to something along the lines of:
RUN apt-get update -yqq; apt-get -yqq install ruby ruby-dev \
          build-essential redis-tools

As a personal suggestion, when you have several commands to run, it is usually better to join them using && rather than ; since you want the build to fail if either command is failing.
RUN apt-get update -yqq && apt-get -yqq install ruby ruby-dev \
          build-essential redis-tools


---

