I am looking at porting a Jenkins non-pipeline job to pipeline. I encountered the situation where, if a parameter value references an environment variable, such as “${HOME}/etc” then the parameter value gets evaluated (eval’d) and then passed to my shell script step as the post-evaluation value “/var/lib/jenkins/etc”.

First of all, I wasn’t expecting this evaluation to occur in the non-pipeline job and couldn’t find documentation that this is supposed to happen. Is this documented somewhere?

Second of all, given that this DOES happen, how do I duplicate the behavior in the pipeline version where the shell script is ran using the sh() command? The Pipeline version gets the parameter avar2 with value ${HOME}/etc. I haven’t found an option where the evaluation can be done for me before running the shell script in a pipeline job. It seems I have to code the script file to do the evaluation on any env variable that might need it.

In the pipeline job, I tried having the shell script specified immediately in the job as well as having the shell script specified in a file in the workspace. I only demonstrate the first case where the shell script is specified immediately in the job here.

I created a Freestyle Job with two string params:

    Name:          avar1
    Default Value: avar1val

    Name:          avar2
    Default Value: ${HOME}/etc

and an “Execute shell” Build Step having the text:

    #!/bin/bash -e
    env | sort

Running this job gives job console text that looks like the following:

    Started by user X
    Running as SYSTEM
    Building on the built-in node in workspace /var/lib/jenkins/workspace/jam
    [jam] $ /bin/bash -e /tmp/jenkins15623yadayada.sh
    avar1=avar1val
    avar2=/var/lib/jenkins/etc
    .
    .
    .
    Finished: SUCCESS

I then created a pipeline job invokes the same shell script using the sh command. Its definition is:

Create a Pipeline Job with two string params:

    Name:          avar1
    Default Value: avar1val

    Name:          avar2
    Default Value: ${HOME}/etc

and the Pipeline definition “Pipeline script”

    pipeline {
        agent any
        stages {
            stage('Hello') {
                steps {
                    sh '''#!/bin/bash -e
                    env | sort
                '''
                }
            }
        }
    }

Running this job includes this text in the Jenkins job Console Output

    .
    .
    avar1=avar1val
    avar2=${HOME}/etc
    .
    .
    Finished: SUCCESS

This is on a linux jenkins v2.452.3 on java 11