For Talend 8 commandline is deprecated, next option to automate build process is cicd,
You can select suitable ci tool like jenkins or azure devops based on that follow below link
CI/CD build using Jenkins, see Continuous Integration and Deployment using Jenkins.
Jenkins internally uses maven to build the Talend job, below is sample command
mvn \
-f <project name>/poms/pom.xml \
-am -pl <comma separated list of jobs modules> \
-Dgeneration.type=local
-Dlicense.path=<license local path or url> \
-Dtalend.studio.p2.base=<P2 update site base url> \
-Dtalend.studio.p2.update=<P2 update folder path or url> \
-Pcloud-publisher
-Dservice.url=<talend cloud service url>
-Dcloud.token=<talend cloud personal access token>
-Dcloud.publisher.screenshot=<true or false>
-Dcloud.publisher.environment=<name of your existing Cloud environment>
-Dcloud.publisher.workspace=<name of your existing Cloud workspace>
clean deploy
here -Dcloud.* part if you are using talend cloud.
