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https://issues.apache.org/jira/browse/HADOOP-14976?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16219394#comment-16219394
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Allen Wittenauer commented on HADOOP-14976:
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bq. allow multi-versioning
Ignoring the whole Linux alternatives bits, it's probably easier to write a
custom hdfs wrapper that does this. e.g.:
/usr/bin/hdfs = wrapper
/usr/hadoop-3.0.0/bin/hdfs = 3.0.0 hdfs
/usr/hadoop-3.1.0/bin/hdfs = 3.1.0 hdfs
/usr/hadoop-default symlink to hadoop-3.0.0
wrapper basically adds --version parameter:
hdfs --version 3.0.0 foo => exec /usr/hadoop-3.0.0/bin/hdfs
hdfs --version 3.1.0 foo => exec /usr/hadoop-3.1.0/bin/hdfs
hdfs foo => exec /usr/hadoop-default/bin/hdfs
Plus this works with any version of Hadoop.... and it's a relatively simple
script. (10 lines max?)
You can also cheat and use .hadoop-env / .hadooprc to do some of the same sorts
of things for individual users, but that's a bit more complicated.
> Allow overriding HADOOP_SHELL_EXECNAME
> --------------------------------------
>
> Key: HADOOP-14976
> URL: https://issues.apache.org/jira/browse/HADOOP-14976
> Project: Hadoop Common
> Issue Type: Improvement
> Reporter: Arpit Agarwal
>
> Some Hadoop shell scripts infer their own name using this bit of shell magic:
> {code}
> 18 MYNAME="${BASH_SOURCE-$0}"
> 19 HADOOP_SHELL_EXECNAME="${MYNAME##*/}"
> {code}
> e.g. see the
> [hdfs|https://github.com/apache/hadoop/blob/trunk/hadoop-hdfs-project/hadoop-hdfs/src/main/bin/hdfs#L18]
> script.
> The inferred shell script name is later passed to _hadoop-functions.sh_ which
> uses it to construct the names of some environment variables. E.g. when
> invoking _hdfs datanode_, the options variable name is inferred as follows:
> {code}
> # HDFS + DATANODE + OPTS -> HDFS_DATANODE_OPTS
> {code}
> This works well if the calling script name is standard {{hdfs}} or {{yarn}}.
> If a distribution renames the script to something like foo.bar, , then the
> variable names will be inferred as {{FOO.BAR_DATANODE_OPTS}}. This is not a
> valid bash variable name.
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