Passing variables extracted from shell in Jenkinsfile - jenkins

Question

I am trying to pass variables extracted in a stage in Jenkinsfile between stages. For example:
stage('Dummy Stage') {
sh '''#!/bin/bash -l
export abc=`output of some command`
.....
.....
'''
Now, how can I pass the variable abc to a subsequent stage? I have tried setting the variable by adding a def section at the top of the file but looks like it doesnt work. In the absence of a neater way, I am having to retype the commands

Answer 1

Here is what I do to get the number of commits on master as a global environment variable:
pipeline {
agent any
environment {
COMMITS_ON_MASTER = sh(script: "git rev-list HEAD --count", returnStdout: true).trim()
}
stages {
stage("Print commits") {
steps {
echo "There are ${env.COMMITS_ON_MASTER} commits on master"
}
}
}
}

Answer 2

You can use the longer form of the sh step and return the output (see Pipeline document). Your variable should be defined outside the stages.

Answer 3

You can use an imperatively created environment variable inside a script block in you stage steps, for example:
stage("Stage 1") {
steps {
script {
env.RESULT_ON_STAGE_1 = sh (
script: 'echo "Output of some command"',
returnStdout: true
)
}
echo "In stage 1: ${env.RESULT_ON_STAGE_1}"
}
}
stage("Stage 2") {
steps {
echo "In stage 2: ${env.RESULT_ON_STAGE_1}"
}
}
This guide explains use of environment variables in pipelines with examples.

Answer 4

My issue concerned having two 'sh' commands where one uses single quotes (where I set a variable) and the other uses double quotes (where I access 'env' variables set in the jenkinsfile such as BUILD_ID).
Here's how I solved it.
script {
env.TEST = sh(
script:
'''
echo "TEST"
''',
returnStdout: true
)
sh """
echo ${env.BUILD_ID}
echo ${env.TEST}
"""
}