How to execute a bash script as sbt task? - sbt

Question

I want to automatically build documentation for my Java Play 2.3 application.
At the moment, I use a Makefile to generate images from *.dotfiles and combine Markdown sources together into Html/PDF:
dot diagram1.dot -Tpdf -o diagram1.pdf
dot diagram2.dot -Tpdf -o diagram2.pdf
pandoc doc1.markdown -o doc1.pdf
# ...
Now I want to run these simple bash commands directly from SBT.
What's the best way to do this?
I found some SBT Documentation plugins in the SBT reference, but nothing to run a simple shell script.

Answer 1

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" !
}

Answer 2

We had the requirement to execute some npm scripts as sbt task and let the build fail if one of the npm scripts fails. Took me some time to find a way to create a Task that works on Windows and Unix. And so here is what I came up with.
lazy val buildFrontend = taskKey[Unit]("Execute frontend scripts")
buildFrontend := {
val s: TaskStreams = streams.value
val shell: Seq[String] = if (sys.props("os.name").contains("Windows")) Seq("cmd", "/c") else Seq("bash", "-c")
val npmInstall: Seq[String] = shell :+ "npm install"
val npmTest: Seq[String] = shell :+ "npm run test"
val npmLint: Seq[String] = shell :+ "npm run lint"
val npmBuild: Seq[String] = shell :+ "npm run build"
s.log.info("building frontend...")
if((npmInstall #&& npmTest #&& npmLint #&& npmBuild !) == 0) {
s.log.success("frontend build successful!")
} else {
throw new IllegalStateException("frontend build failed!")
}
},
(run in Compile) <<= (run in Compile).dependsOn(buildFrontend)