Merge pull request #3153 from dwijnand/kill-enter-to-stay-in-shell

Remove the "hit [ENTER] to switch to interactive mode" feature

main/command/src/main/scala/sbt/State.scala

@@ -182,11 +182,8 @@ object State {
         log.debug(s"> $cmd")
         f(cmd, s.copy(remainingCommands = remainingCommands, history = cmd :: s.history))
       }
-      def isInteractive = System.console != null
-      def hasInput = Option(System.console) exists (_.reader.ready())
-      def hasShellCmd = s.definedCommands exists { case c: SimpleCommand => c.name == Shell; case _ => false }
       s.remainingCommands match {
-        case Seq()           => if (isInteractive && hasInput && hasShellCmd) runCmd(Shell, Nil) else exit(true)
+        case Seq()           => exit(true)
         case Seq(x, xs @ _*) => runCmd(x, xs)
       }
     }

main/src/main/scala/sbt/Main.scala

@@ -570,14 +570,12 @@ object BuiltinCommands {
   private def writeSbtVersion: Command =
     Command.command(WriteSbtVersion) { state => writeSbtVersion(state); state }
 
-  private def isInteractive = System.console() != null
-
   private def intendsToInvokeCompile(state: State) = state.remainingCommands contains Keys.compile.key.label
 
   private def notifyUsersAboutShell(state: State): Unit = {
     val suppress = Project extract state getOpt Keys.suppressSbtShellNotification getOrElse false
-    if (!suppress && isInteractive && intendsToInvokeCompile(state))
-      state.log info "Executing in batch mode. For better performance use sbt's shell; hit [ENTER] to do so now"
+    if (!suppress && intendsToInvokeCompile(state))
+      state.log info "Executing in batch mode. For better performance use sbt's shell"
   }
 
   private def NotifyUsersAboutShell = "notify-users-about-shell"

notes/0.13.16.markdown

@@ -1,3 +1,6 @@
+### Fixes with compatibility implications
+
+- Removes the "hit \[ENTER\] to switch to interactive mode" feature. See below.
 
 ### Improvements
 
@@ -31,6 +34,23 @@ When informing the user about sbt's shell the messaging now:
 
 [#3091][3091]/[#3097][3097]/[#3147][3147] by [@dwijnand][@dwijnand]
 
+### Remove the "hit \[ENTER\] to switch to interactive mode" feature
+
+In sbt 0.13.15, in addition to notifying the user about the existence of sbt's shell, a feature was added to
+allow the user to switch to sbt's shell - a more pro-active approach to just displaying a message.
+
+Unfortunately sbt is often unintentionally invoked in shell scripts in "interactive mode" when no interaction is
+expected by, for exmaple, invoking `sbt package` instead of `sbt package < /dev/null`. In that case hitting
+\[ENTER\] would silently trigger sbt to run its shell, easily wrecking the script. In addition to that I was
+unhappy with the implementation as it created a tight coupling between sbt's command processing abstraction to
+sbt's shell command.
+
+If you want to stay in sbt's shell after running a task like `package` then invoke sbt like so:
+
+    sbt package shell
+
+[#3091][3091]/[#3153][3153] by [@dwijnand][@dwijnand]
+
 ### sbt-cross-building
 
 [@jrudolph][@jrudolph]'s sbt-cross-building is a plugin author's plugin.
@@ -67,6 +87,7 @@ Then, run:
   [3097]: https://github.com/sbt/sbt/issues/3097
   [3147]: https://github.com/sbt/sbt/pull/3147
   [3133]: https://github.com/sbt/sbt/pull/3133
+  [3153]: https://github.com/sbt/sbt/pull/3153
   [@jrudolph]: https://github.com/jrudolph
   [@eed3si9n]: https://github.com/eed3si9n
   [@dwijnand]: https://github.com/dwijnand