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https://issues.apache.org/jira/browse/HADOOP-11460?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14297424#comment-14297424
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Allen Wittenauer commented on HADOOP-11460:
-------------------------------------------
I think I found it. Also, I think since the old vars are deprecated, we
shouldn't populate them. It will encourage folks to stop using them in new
code... and given this is trunk, I think that's ok. Oh, and this uses quotes
because YARN_OPT. :(
{code}
function hadoop_deprecate_envvar
{
local oldvar=$1
local newvar=$2
local oldval=${!oldvar}
local newval=${!newvar}
if [[ -n "${oldval}" ]]; then
hadoop_error "WARNING: ${oldvar} has been replaced by ${newvar}. Using
value of ${oldvar}."
# shellcheck disable=SC2086
eval ${newvar}=\"${oldval}\"
# shellcheck disable=SC2086
newval=${oldval}
# shellcheck disable=SC2086
eval ${newvar}=\"${newval}\"
fi
}
{code}
> Deprecate shell vars
> --------------------
>
> Key: HADOOP-11460
> URL: https://issues.apache.org/jira/browse/HADOOP-11460
> Project: Hadoop Common
> Issue Type: New Feature
> Components: scripts
> Affects Versions: 3.0.0
> Reporter: Allen Wittenauer
> Assignee: John Smith
> Labels: scripts, shell
> Attachments: HADOOP-11460-00.patch, HADOOP-11460-01.patch,
> HADOOP-11460-02.patch, HADOOP-11460-03.patch
>
>
> It is a very common shell pattern in 3.x to effectively replace sub-project
> specific vars with generics. We should have a function that does this
> replacement and provides a warning to the end user that the old shell var is
> deprecated. Additionally, we should use this shell function to deprecate the
> shell vars that are holdovers already.
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