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thaJeztah merged 1 commit into from
Jan 17, 2018
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Improve builder ENV docs #814

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12 changes: 6 additions & 6 deletions docs/reference/builder.md
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Expand Up @@ -805,14 +805,15 @@ see the
ENV <key>=<value> ...

The `ENV` instruction sets the environment variable `<key>` to the value
`<value>`. This value will be in the environment of all "descendant"
`Dockerfile` commands and can be [replaced inline](#environment-replacement) in
`<value>`. This value will be in the environment for all subsequent instructions
in the build stage and can be [replaced inline](#environment-replacement) in
many as well.

The `ENV` instruction has two forms. The first form, `ENV <key> <value>`,
will set a single variable to a value. The entire string after the first
space will be treated as the `<value>` - including characters such as
spaces and quotes.
space will be treated as the `<value>` - including whitespace characters. The
value will be interpreted for other environment variables, so quote characters
will be removed if they are not escaped.

The second form, `ENV <key>=<value> ...`, allows for multiple variables to
be set at one time. Notice that the second form uses the equals sign (=)
Expand All @@ -830,8 +831,7 @@ and
ENV myDog Rex The Dog
ENV myCat fluffy

will yield the same net results in the final image, but the first form
is preferred because it produces a single cache layer.
will yield the same net results in the final image.

The environment variables set using `ENV` will persist when a container is run
from the resulting image. You can view the values using `docker inspect`, and
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