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Accessing parameters in shell scripts

• Job parameters and order parameters are accessible by exposed as environment variables to shell jobsscripts.
• There is a simple rule for the naming of environment variablesEnvironment variables are named using a predefined prefix and the name of the original parameter: 
  • The name of default value for the environment variable for a parameter is prefix is SCHEDULER_PARAM_NAMEOFPARAM . 
  • Environment variable names are provided with uppercase letters.
  • For example the job , a parameter param1 is available can be accessed by the environment variable SCHEDULER_PARAM_PARAM1
  • Environment variables are used with uppercase letters

  • If you wanted not to use the prefix SCHEDULER_PARAM_ and instead use the parameter names as environment variables then you could add the following setting to your ./config/scheduler.xml file:

    Code Block
    language xml
    <params> <param name="scheduler.variable_name_prefix" value="*NONE"/> ... </param>

     Hint: You have been warned, JobScheduler would overwrite existing environment variables with the same name for the respective shell.

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• • environment variable.

  • For details see Which environment variables are provided by JobScheduler?

Examples

The following two examples show a task parameter defined in a job <param> tag can be called in a shell script.

 <job>
    <params>
        <param name="param1"  value="Test"/>
    </params>
    <script language="shell">
        <![CDATA[
 rem This is an example shell script to show the use of parameters
 echo Param1 has the value %SCHEDULER_PARAM_PARAM1%
        ]]>
    </script>
    <run_time/>
 </job>

 <job>
    <params>
        <param name="param1" value="Test"/>
    </params>
    <script language="shell">
        <![CDATA[
 # This is an example shell script to show the use of parameters
 echo "Param1Parameter param1 has the value $SCHEDULER_PARAM_PARAM1"
        ]]>
    </script>
    <run_time/>
 </job

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If you want to use parameters as command line arguments for a script then just add the environment variables as arguments in the command line:

  anyshellscript.sh $SCHEDULER_PARAM_PARAM1 $SCHEDULER_PARAM_PARM2 ...

Passing parameters to subsequent shell jobs in a job chain

• JobScheduler allows the creation or overwriting of order parameters for subsequent jobs in a job chain.
• With every change of status in job chains JobScheduler parses a temporary file for name=/value pairs . after termination of each job in a job chain.
  • The name of the this temporary file is available with held in the environment variable SCHEDULER_RETURN_VALUES environment variable.
  • The name/value pairs are automatically added as order parameters.
  • A parameter set in one job shell script can be written to this temporary file and made available to subsequent jobs using the following (for Windows):
    
    • myParam=myValue >> %SCHEDULER_RETURN_VALUES%
  • A task parameter set in one job can be written to this temporary file and thereby made available to subsequent jobs in a job chain using the following (for Windows):
    • myParam=%SCHEDULER_PARAM_MYPARAM% >> %SCHEDULER_RETURN_VALUES%
  • Such parameters are accessible in subsequent job using the following (for Windows):
    • echo myParam = %SCHEDULER_PARAM_MYPARAM%

The following code blocks show two jobs that demonstrate the setting and retrieval of shell script parameters in a job chain:.

 <job order="yes"
     stop_on_error="no" name="job1_shell_with_parameter_set">
    <params>
        <param name="param1" value="Value1-Job1" />
        <param name="param2" value="TestValue2-Job1" />
    </params>
    <script language="shell">
        <![CDATA[
 rem This is ana examplesample shell script to demonstrate the usesetting of parameters 
echo param1 = %SCHEDULER_PARAM_PARAM1%
echo param2 newParam=an example value= %SCHEDULER_PARAM_PARAM2% 
 
rem creating order parameters for subsequent jobs
echo param2 = some-other-value >> %SCHEDULER_RETURN_VALUES%
echo param3 = Value3 >> %SCHEDULER_RETURN_VALUES%
        ]]>
    </script>
    <run_time/>
 </job>

 <job order="yes" stop_on_error="no" name="job2_shell_with_parameter_get">
    <params>
        <param name="param1" value="Value1-Job2" />
        <param name="Test""param2" value="Value2-Job2" />
    </params>
    <script language="shell">
        <![CDATA[
echo param1 has the value: %SCHEDULER_PARAM_PARAM1%
echo param2 has the value: %SCHEDULER_PARAM_PARAM2%
echo newParamparam3 has the value: %SCHEDULER_PARAM_NEWPARAM%PARAM3%
        ]]>
    </script>
    <run_time/>
 </job>

The job chain for the two example shell jobs is listed below:

 <job_chain>
    <job_chain_node state="100"
                    job="job_samplejob1_shell_with_parameter_set"
                    next_state="200"
                    error_state="error"/>
    <job_chain_node state="200"
                    job="job_sample_shelljob2_shell_with_parameter_get"
                    next_state="success"
                    error_state="error"/>
    <job_chain_node state="success"/>
    <job_chain_node state="error"/>
 </job_chain>

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Example Behavior

The screen shot below shows the log file for the example order and the values for the environment variables.

Image Added

The log file shows that:

• The param1 task parameters set in both the first and second jobs are only valid within the respective jobs.
• The param2 task parameter set in the first job and which is forwarded as an environment variable to the second job overwrites the param2 task parameter set in the second job.
• The param3 shell script parameter set in the shell script in the first job is passed to the script in the second job.

Example Download

The example described above can be downloaded from the following link:

• sample_shell_jobjobs_with_parameter.zipparameters.zip

Unpack the files into your JobScheduler's live folder and run the order using JOC.

The example behavior described above will be visible in the order log file.

Further References

Job and Order Parameters

• How to set and read job and order parameters
• How to access order parameters and job parameters using the JobScheduler API
• How to specify parameters using the "on_exit_code" command
• How to clone parameters from a persistent order