[FIXED] How to echo a shell script to a file in groovy interface like Jenkinsfile

Issue

I have the below shell script that i need to echo to a file lets say script.sh from a groovy interface like Jenkinsfile but keep getting compilation errors.

class="snippet-code">

#!/bin/bash
commit_hash=$(git rev-parse HEAD)
parent_hashes=`git rev-list --parents -n 1 $commit_hash`
parent_count=`wc -w <<< $parent_hashes`
if [[ $parent_count -gt 2 ]]
then
  p=`git name-rev $parent_hashes | xargs -0 | grep -e '^\S\+ master$'`
  if [[ ! -z $p ]]
  then
    echo "merged branch is master"
    exit 0
  else
    echo "merged branch is anything but master"
    exit 2
  fi
else
  echo "no branch merged"
  exit 1
fi

I tried the below :-

sh '''echo '#!/bin/bash
               commit_hash=$(git rev-parse HEAD)
               parent_hashes=`git rev-list --parents -n 1 $commit_hash`
               parent_count=`wc -w <<< $parent_hashes`
               if [[ $parent_count -gt 2 ]]
                 then
               p=`git name-rev $parent_hashes | xargs -0 | grep -e '^\S\+ master$'`
               if [[ ! -z $p ]]
                  then
               echo "merged branch is master"
               exit 0
               else
              echo "merged branch is anything but master"
               exit 2
                fi
               else
              echo "no branch merged"
               exit 1
                fi' > script.sh'''

I see the shell script has single quotes in a line plus a few back slashes, so not sure why groovy is not allowing normal shell interpolation here. How do i get to echo the contents of this shell script to a file using groovy. I am trying this out in scripted Jenkinsfile.

Solution

You can try using writeFile option to write the content into file, but in your case you have to escape backslash alone in your script. Below should work.

pipeline {
    agent any
    stages {
        stage ("Test") {
            steps{
                writeFile file:'test.txt', text: '''#!/bin/bash
commit_hash=$(git rev-parse HEAD)
parent_hashes=`git rev-list --parents -n 1 $commit_hash`
parent_count=`wc -w <<< $parent_hashes`
if [[ $parent_count -gt 2 ]]
then
  p=`git name-rev $parent_hashes | xargs -0 | grep -e '^\\S\\+ master$'`
  if [[ ! -z $p ]]
  then
    echo "merged branch is master"
    exit 0
  else
    echo "merged branch is anything but master"
    exit 2
  fi
else
  echo "no branch merged"
  exit 1
fi'''
            }
        }
    }
}

Answered By - Kiruba
Answer Checked By - Katrina (JavaFixing Volunteer)