How to use sbt-eclipse to create Eclipse project files of a project?

I'm using sbt 0.13.5.

$ sbt --version
sbt launcher version 0.13.5

In an empty directory executed sbt about to check the build/sbt setup.

$ sbt about
[info] Loading global plugins from /Users/jacek/.sbt/0.13/plugins
[info] Updating {file:/Users/jacek/.sbt/0.13/plugins/}global-plugins...
[info] Resolving org.fusesource.jansi#jansi;1.4 ...
[info] Done updating.
[info] Set current project to sbteclipse (in build file:/Users/jacek/sandbox/sbteclipse/)
[info] This is sbt 0.13.5
[info] The current project is {file:/Users/jacek/sandbox/sbteclipse/}sbteclipse 0.1-SNAPSHOT
[info] The current project is built against Scala 2.10.4
[info] Available Plugins: sbt.plugins.IvyPlugin, sbt.plugins.JvmPlugin, sbt.plugins.CorePlugin, sbt.plugins.JUnitXmlReportPlugin, net.virtualvoid.sbt.graph.Plugin, com.timushev.sbt.updates.UpdatesPlugin
[info] sbt, sbt plugins, and build definitions are using Scala 2.10.4

No files are in the directory (disregard target since it's automatically created by sbt upon startup and can be removed at any time).

$ tree
.
`-- target

1 directory, 0 files

I then ran the sbt shell with sbt to ensure no eclipse command existed.

$ sbt
[info] Loading global plugins from /Users/jacek/.sbt/0.13/plugins
[info] Set current project to sbteclipse (in build file:/Users/jacek/sandbox/sbteclipse/)
> eclipse
[error] Not a valid command: eclipse (similar: help, alias)
[error] Not a valid project ID: eclipse (similar: sbteclipse)
[error] Expected ':' (if selecting a configuration)
[error] Not a valid key: eclipse (similar: deliver, licenses, clean)
[error] eclipse
[error]        ^

I could reproduce your issue. Moving on to setting up the plugin - I did not close the sbt shell.

Following the documentation closely I opened ~/.sbt/0.13/plugins/plugins.sbt to have it as follows:

$ cat ~/.sbt/0.13/plugins/plugins.sbt
addSbtPlugin("com.typesafe.sbteclipse" % "sbteclipse-plugin" % "2.5.0")

With the plugin in the file, I fired reload in the sbt shell to load the changes.

> reload
[info] Loading global plugins from /Users/jacek/.sbt/0.13/plugins
[info] Updating {file:/Users/jacek/.sbt/0.13/plugins/}global-plugins...
[info] Resolving org.fusesource.jansi#jansi;1.4 ...
[info] Done updating.
[info] Set current project to sbteclipse (in build file:/Users/jacek/sandbox/sbteclipse/)
> eclipse
[info] About to create Eclipse project files for your project(s).
[info] Updating {file:/Users/jacek/sandbox/sbteclipse/}sbteclipse...
[info] Resolving org.fusesource.jansi#jansi;1.4 ...
[info] Done updating.
[info] Successfully created Eclipse project files for project(s):
[info] sbteclipse

As you can see the plugin was properly loaded and generated the files. Follow the steps and you should have the plugin installed with no issues.

The warning in lines 2-4 is telling you to move your plugins folder from ~/.sbt/plugins/plugins.sbt to ~/.sbt/0.13/plugins/plugins.sbt.

For sbt 0.13 and up

Add sbteclipse to your plugin definition file. You can use either:

1. the global file (for version 0.13 and up) at ~/.sbt/0.13/plugins/plugins.sbt

2. the project-specific file at PROJECT_DIR/project/plugins.sbt

   addSbtPlugin("com.typesafe.sbteclipse" % "sbteclipse-plugin" % "2.5.0")