You can find some answers in External Processes in the official documentation of sbt, e.g.
To run an external command, follow it with an exclamation mark !:
"find project -name *.jar" !
Don’t forget to use import scala.sys.process._ so ! can be resolved as a method of String.
Do the following in activator console (aka sbt shell) to execute yourshell.sh – mind the eval command and the quotes around the name of the script:
eval "yourshell.sh" !
To have it available as a task add the following to build.sbt of your project:
lazy val execScript = taskKey[Unit]("Execute the shell script")
execScript := {
"yourshell.sh" !
}