With SBT, how do I a specify an alternate project root other than the current directory for running a main class?

Question

Normally SBT looks for the build files at ./build.sbt and ./project/Build.scala. Is it possible to specify an alternate project root, so I can buil

Answer 1

As I discovered from this other answer, the sbt-start-script plugin is a better tool for this than sbt run-main. You can simply run sbt stage and you get an invocation script, with classpaths resolved, at target/start. According to the documentation, it needs to be run from the build root directory for inter-project dependencies to work, but for my simple use cases, this doesn't seem to be a problem.

Answer 2

I have something like this. I have project definition at X/build.sbt, X/MyOtherDefinitionWithSpecialThing/build.sbt, X/MySuperPublishConfig/build.sbt.

But my point of view to the problem is opposite. Instead of specify location of ./build.sbt and ./project/Build.scala I specify location of path to resources. The result is the same. It looks like:

sourceDirectory <<= (baseDirectory) (_ / ".." / "src")

target <<= (baseDirectory) (_ / ".." / "target")

This is allow to create single project with multiple definitions. This is worked with nested/hierarchical projects. But I use symbolic links (Linux OS) for hierarchical projects.

There is a file tree of one of my SBT plugins. Multiple build definitions and only one src/...

.
|-build.sbt
|-project
|---project
|-----target
|-------...
|---target
|-----...
|-project-0.11
|---build.sbt
|---project
|-----project
|-------target
|---------...
|-----target
|-------...
|-project-0.12
|---build.sbt
|---project
|-----project
|-------target
|---------...
|-----target
|-------...
|-...
|-src
|---main
|-----scala
|-------org
|---------...
|---sbt-test
|-----...
|-target
|---...

If this not solution of your problem please elaborate why you don't want use 'cd' command ;-)

-- For the updated use case:

I use shell wrapper and I have symlink to this one in every SBT project:

#!/bin/sh
#
here=$(cd $(dirname "$0"); pwd)
if [ ! -e "${here}/build.sbt" ]
then
  echo build.sbt lost
  exit
fi
cd ${here} 

LOCAL_BUILD=true sbt-0.12 "$@"

I simply write /path/to/my/project/sbt 'show name' for example or /path/to/my/project/sbt run-main in your case.