Make an alias with Dockerfile for Ubuntu image

Why aren’t my aliases sticky? ;_;

You cannot just simply set an alias in your Dockerfile:

# syntax=docker/dockerfile:1

FROM ubuntu:18.04

RUN alias dir='ls -halp'

They don’t stick. You might be wondering why, since you seem to be able to use the RUN command to easily run “apt-get” and other command line tools, and those apt-get installs don’t disappear, so how come my alias is disappearing? It is disappearing because when you call RUN you are opening a new shell instance. You need to set your bashrc file with the alias you want so that each shell instance will initialize your alias on startup.

You need to add it to a bashrc file. This will only apply to interactive terminals. [1]

RUN echo 'alias hi="echo hello"' >> ~/.bashrc

This will set an alias so that when you type “hi” into the terminal, it will echo “hello” back to you.

The >> is a stream operator, so you are streaming the string inside the single quotes into the text file at ~/.bashrc.

I am fond of always adding this one to all my Dockerfiles:

RUN echo 'alias ls="ls -halp"' >> ~/.bashrc

so that when I run ls I can get a more detailed view.

References

[1] How can I set Bash aliases for docker containers in Dockerfile? https://stackoverflow.com/questions/36388465/how-can-i-set-bash-aliases-for-docker-containers-in-dockerfile