From e6c152e5ee579a9d7806e0c121aa7a118cbc4696 Mon Sep 17 00:00:00 2001 From: David Dooling Date: Wed, 17 Aug 2016 06:31:19 -0500 Subject: [PATCH] Make it clear who is doing variable expansion Add sentece to RUN, CMD, and ENTRYPOINT exec sections making it clear that it is the shell doing the environment variable expansion. Signed-off-by: David Dooling --- docs/reference/builder.md | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/docs/reference/builder.md b/docs/reference/builder.md index b84f1811f2..c63bcf5347 100644 --- a/docs/reference/builder.md +++ b/docs/reference/builder.md @@ -541,6 +541,9 @@ RUN /bin/bash -c 'source $HOME/.bashrc ; echo $HOME' > `RUN [ "echo", "$HOME" ]` will not do variable substitution on `$HOME`. > If you want shell processing then either use the *shell* form or execute > a shell directly, for example: `RUN [ "sh", "-c", "echo $HOME" ]`. +> When using the exec form and executing a shell directly, as in the case for +> the shell form, it is the shell that is doing the environment variable +> expansion, not docker. > > **Note**: > In the *JSON* form, it is necessary to escape backslashes. This is @@ -607,6 +610,9 @@ instruction as well. > `CMD [ "echo", "$HOME" ]` will not do variable substitution on `$HOME`. > If you want shell processing then either use the *shell* form or execute > a shell directly, for example: `CMD [ "sh", "-c", "echo $HOME" ]`. +> When using the exec form and executing a shell directly, as in the case for +> the shell form, it is the shell that is doing the environment variable +> expansion, not docker. When used in the shell or exec formats, the `CMD` instruction sets the command to be executed when running the image. @@ -1075,6 +1081,9 @@ sys 0m 0.03s > `ENTRYPOINT [ "echo", "$HOME" ]` will not do variable substitution on `$HOME`. > If you want shell processing then either use the *shell* form or execute > a shell directly, for example: `ENTRYPOINT [ "sh", "-c", "echo $HOME" ]`. +> When using the exec form and executing a shell directly, as in the case for +> the shell form, it is the shell that is doing the environment variable +> expansion, not docker. ### Shell form ENTRYPOINT example