Oozie shell action: exec and file tags

[#1]

I'm a newbie in Oozie and I've read some Oozie shell action examples but this got me confused about certain things.

There are examples I've seen where there is no <file> tag.

Some example, like in Cloudera here, repeats the shell script in file tag:

<shell xmlns="uri:oozie:shell-action:0.2">
    <exec>check-hour.sh</exec>
    <argument>${earthquakeMinThreshold}</argument>
    <file>check-hour.sh</file>
</shell>

While in Oozie's website, writes the shell script (the reference `${EXEC}` from job.properties, which points to script.sh file) twice, separated by #.

<shell xmlns="uri:oozie:shell-action:0.1">
    ...
    <exec>${EXEC}</exec>
    <argument>A</argument>
    <argument>B</argument>
    <file>${EXEC}#${EXEC}</file>
</shell>

There are also examples I've seen where the path (HDFS or local?) is prepended before the `script.sh#script.sh` within the <file> tag.

<shell xmlns="uri:oozie:shell-action:0.1">
    ...
    <exec>script.sh</exec>
    <argument>A</argument>
    <argument>B</argument>
    <file>/path/script.sh#script.sh</file>
</shell>

As I understand, any shell script file can be included in the workflow HDFS path (same path where workflow.xml resides).

Can someone explain the differences in these examples and how `<exec>`, `<file>`, `script.sh#script.sh`, and the `/path/script.sh#script.sh` are used?

[#2 · Accepted solution]

Lets say you want to execute "script.sh"

1. If you have script.sh inside your WF/lib/ path on HDFS, you just need <exec>script.sh</exec>

2. If you have script.sh on an arbitrary path on HDFS, you need:

<exec>script.sh</exec>
<file>/path/to/script.sh#script.sh</file>

3. Use of the below form with (1) is redundant, but the subsequent form is when you want to invoke it as a different name:

<exec>script.sh</exec>
<file>script.sh#script.sh</file>

<exec>linked-script-name.sh</exec>
<file>original-script-name.sh#linked-script-name.sh</file>