% sbt -v -sbt-snapshot -210 -sbt-create about
Detected sbt version 0.11.3-SNAPSHOT
sbt snapshot is 0.11.3-20111207-052114
# Executing command line:
java
-XX:+CMSClassUnloadingEnabled
-Xms1536m
-Xmx1536m
-XX:MaxPermSize=384m
-XX:ReservedCodeCacheSize=192m
-Dfile.encoding=UTF8
-jar
/r/sbt-extras/.lib/0.11.3-SNAPSHOT/sbt-launch.jar
"set resolvers in ThisBuild += ScalaToolsSnapshots"
"++ 2.10.0-SNAPSHOT"
about

[info] Loading global plugins from /Users/paulp/.sbt/plugins
[info] Set current project to default-71999b (in build file:/Users/paulp/Desktop/new/)
[info] Reapplying settings...
[info] Set current project to default-71999b (in build file:/Users/paulp/Desktop/new/)
Setting version to 2.10.0-SNAPSHOT
[info] Set current project to default-71999b (in build file:/Users/paulp/Desktop/new/)
[info] This is sbt 0.11.3-20111207-052114
[info] The current project is {file:/Users/paulp/Desktop/new/}default-71999b
[info] The current project is built against Scala 2.10.0-SNAPSHOT
[info] sbt, sbt plugins, and build definitions are using Scala 2.9.1

Usage: sbt [options]

  -h | -help         print this message
  -v | -verbose      this runner is chattier
  -d | -debug        set sbt log level to debug
  -no-colors         disable ANSI color codes
  -sbt-create        start sbt even if current directory contains no sbt project
  -sbt-dir   <path>  path to global settings/plugins directory (default: ~/.sbt)
  -sbt-boot  <path>  path to shared boot directory (default: ~/.sbt/boot in 0.11 series)
  -ivy       <path>  path to local Ivy repository (default: ~/.ivy2)
  -mem    <integer>  set memory options (default: 1536, which is -Xms1536m -Xmx1536m -XX:MaxPermSize=384m -XX:ReservedCodeCacheSize=192m)
  -no-share          use all local caches; no sharing
  -offline           put sbt in offline mode
  -jvm-debug <port>  Turn on JVM debugging, open at the given port.

  # sbt version (default: from project/build.properties if present, else latest release)
  -sbt-version  <version>   use the specified version of sbt
  -sbt-jar      <path>      use the specified jar as the sbt launcher
  -sbt-rc                   use an RC version of sbt
  -sbt-snapshot             use a snapshot version of sbt

  # scala version (default: latest release)
  -28                       use 2.8.2
  -29                       use 2.9.1
  -210                      use 2.10.0-SNAPSHOT
  -scala-home <path>        use the scala build at the specified directory
  -scala-version <version>  use the specified version of scala

  # java version (default: java from PATH, currently java version "1.6.0_29")
  -java-home <path>         alternate JAVA_HOME

  # jvm options and output control
  JAVA_OPTS     environment variable, if unset uses "-Dfile.encoding=UTF8"
  SBT_OPTS      environment variable, if unset uses "-XX:+CMSClassUnloadingEnabled"
  .sbtopts      if this file exists in the sbt root, it is prepended to the runner args
  -Dkey=val     pass -Dkey=val directly to the java runtime
  -J-X          pass option -X directly to the java runtime (-J is stripped)

In the case of duplicated or conflicting options, the order above
shows precedence: JAVA_OPTS lowest, command line options highest.