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https://issues.apache.org/jira/browse/HADOOP-4868?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12660984#action_12660984
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Doug Cutting commented on HADOOP-4868:
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I would prefer that the included scripts were not directly in the bin/
directory, but rather in lib/ or a subdirectory. The bin/ directory should
ideally only contain end-user commands.
Also, once we split the projects, we'd like the combination of core & mapred
and core & hdfs to be as simple as possible. Copying multiple scripts into
directories seems fragile. Ideally we'd have a single shell script to
bootstrap things and then get everything else from jars on the classpath, since
we need to combine libraries (core, hdfs, & mapred) together on the classpath
anyway.
Might it be simpler if the command dispatch were in Java? We might have a
CoreCommand, plus MapredCommand and HdfsCommand subclasses. The bin/hadoop
script (from core) might, when invoked with 'bin/hadoop foo ...' run something
like org.apache.hadoop.foo.FooCommand. Then we wouldn't need the core.sh,
mapred.sh and hdfs.sh include scripts.
BTW, a perhaps little-known feature of hadoop is that it bundles the contents
of bin/ into the jar, so that the jar contains (with a little unpacking) the
tools needed to use it. We could continue this after the project splitup, so
that all that, e.g., all that hdfs should need from a core release is its jar.
When we build an hdfs release we can unpack bin/hadoop from the core jar.
> Split the hadoop script into 3 parts
> ------------------------------------
>
> Key: HADOOP-4868
> URL: https://issues.apache.org/jira/browse/HADOOP-4868
> Project: Hadoop Core
> Issue Type: Improvement
> Components: scripts
> Reporter: Sharad Agarwal
> Assignee: Sharad Agarwal
> Attachments: 4868_v1.patch, 4868_v2.patch
>
>
> We need to split the bin/hadoop into 3 parts for core, mapred and hdfs. This
> will enable us to distribute the individual scripts with each component.
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