variables not getting populated in sh of jenkins pipeline - shell

Question

I have the below code and username,pwd and modulename from previous stages are not getting populated when I'm doing curl in sh script.
Please let me know what do I need to fix it
def USERNAME
def PASSWORD
def MODULE_NAME
node {
try {
stage('userAuth') {
withCredentials([[$class: 'UsernamePasswordMultiBinding', credentialsId: 'ID-Creds',
usernameVariable: 'user', passwordVariable: 'pwd']]) {
USERNAME="$user"
PASSWORD="$pwd"
echo "$USERNAME:$PASSWORD" //This is fine
}
}
stage('readPOM') {
def pom = readMavenPom file: 'pom.xml'
MODULE_NAME = pom.module
echo "$MODULE_NAME" //This is printing fine
}
stage('do curl') {
def revision = sh(script: '''
AUTH="$USERNAME:$PASSWORD"; //Not getting populated getting empty
RespInfo=$(curl -u $AUTH "https://host/apis/${MODULE_NAME}/deployments"); //Not getting populated getting empty for modulename
currntRev=$(jq -r .revision[0].name <<< "${RespInfo}");
echo $currntRev
''',returnStdout: true).split()
}
}
catch (e) {
throw e
} finally {
}
}

Answer 1

You have to use double quotes (""") to apply string interpolation:
def revision = sh(script: """
AUTH=\"$USERNAME:$PASSWORD\"; //Not getting populated getting empty

Answer 2

A easier way is to concat two strings as following:
def revision = sh(
returnStdout: true,
script: '''
AUTH="$user:$pwd";
RespInfo=$(curl -u "$AUTH" "https://host/apis/''' + MODULE_NAME + '''/deployments");
currntRev=$(jq -r .revision[0].name <<< "${RespInfo}");
echo $currntRev
'''
).split()
Note: string wrapped in """ will be expanded, but not when wrapped in '''
USERNAME and PASSWORD are Groovy variable, when they are wrapped in """ or "", Groovy executor will expand them before script be executed.
user and pwd are Shell variable, we should use Shell variable when use '''