Jenkins: How to change shell in Scripted Pipeline?

Question

Print default shell with below script.

node {
    stage('Clean'){
        echo "${SHELL}"
...
}

From log, it's /usr/local/bin/tcsh.

[Pipeline] echo  
/usr/local/bin/tcsh

How to change it to another shell, like /bin/csh?

Answer 1

Tried below code, echo still prints "/usr/local/bin/tcsh", but suddenly /bin/csh environment variable is available.

stage('Clean'){
        sh '''#!/bin/csh
                echo "Clean old coverage data"
                echo "${SHELL}"
        '''
}