Get param from env var after setting by script pipeline

gistfile1.txt

//tmp.sh export foo=bar
getFoo = " "
pipeline {
   environment {
         a="d"
        // b="changeable"
        
        
    }
    agent {

    node {
        label 'master'
    }

}

    stages {
       
         stage('cluster creation') {
            steps {
                script{
                    
                    
                    // Original Map structure.


                ALl_VARS = sh (
                script: 'source ./tmp.sh > /dev/null ;printenv;',
                returnStdout: true
                    ).replaceAll("[\n\r]", " ");
                   
                def mapEnvs =
   
    //cast to map
    ALl_VARS[1..-2]
        // Split on , to get a List.
        .split(' ')
        // Each list item is transformed
        // to a Map entry with key/value.
        .collectEntries { entry ->
            def pair = entry.split('=')
           // echo pair.toString()
            [(pair.first()): pair.last()]
        }


            //print foo specifically   
             print mapEnvs.foo //==bar
             //or assign to getFoo
             getFoo=mapEnvs.foo.toString() //==bar
             //print getFoo 
             echo "${getFoo}" //==bar
                

                }
               
                
            
            }
        }
      
      

    }
   
}
return;