--- a/AbstractOperatingSystem.st	Tue Jul 10 13:58:33 2018 +0200
+++ b/AbstractOperatingSystem.st	Tue Jul 10 16:38:12 2018 +0200
@@ -911,8 +911,9 @@
 !AbstractOperatingSystem class methodsFor:'executing OS commands-implementation'!
 
 exec:aCommandPath withArguments:argArray environment:env fileDescriptors:fds fork:doFork
-		  newPgrp:newGrp inDirectory:aDirectory showWindow:showWindowBooleanOrNil
-    "execute an OS command"
+                  newPgrp:newGrp inDirectory:aDirectory showWindow:showWindowBooleanOrNil
+    "execute an OS command, return a pid.
+     Notice: on Unix, this id is an integer; on Windows, it is a processhandle."
 
     ^ self subclassResponsibility
 
@@ -950,6 +951,7 @@
      The command gets stdIn, stdOut and stdErr assigned from the arguments;
      each may be nil.
      Return the processId if successful, nil otherwise.
+     Notice: on Unix, this id is an integer; on Windows, it is a processhandle.
      Use #monitorPid:action: for synchronization and exec status return,
      or #killProcess: to stop it."
 
@@ -958,37 +960,37 @@
     aCommandString isNil ifTrue:[^ nil].
 
     (in := anExternalInStream) isNil ifTrue:[
-	nullStream := Filename nullDevice readWriteStream.
-	in := nullStream.
+        nullStream := Filename nullDevice readWriteStream.
+        in := nullStream.
     ].
     (out := anExternalOutStream) isNil ifTrue:[
-	nullStream isNil ifTrue:[nullStream := Filename nullDevice writeStream].
-	out := nullStream.
+        nullStream isNil ifTrue:[nullStream := Filename nullDevice writeStream].
+        out := nullStream.
     ].
     (err := anExternalErrStream) isNil ifTrue:[
-	err := out
+        err := out
     ].
     anAuxiliaryStream notNil ifTrue:[
-	auxFd := anAuxiliaryStream fileHandle.
+        auxFd := anAuxiliaryStream fileHandle.
     ].
 
     shellAndArgs := self commandAndArgsForOSCommand:aCommandString.
 
     pid := self
-	exec:(shellAndArgs at:1)
-	withArguments:(shellAndArgs at:2)
-	environment:anEvironmentDictionary
-	fileDescriptors:(Array with:in fileHandle
-			       with:out fileHandle
-			       with:err fileHandle
-			       with:auxFd)
-	fork:true
-	newPgrp:newPgrp
-	inDirectory:dir
-	showWindow:(showWindowBooleanOrNil ? (shellAndArgs at:3)).
+        exec:(shellAndArgs at:1)
+        withArguments:(shellAndArgs at:2)
+        environment:anEvironmentDictionary
+        fileDescriptors:(Array with:in fileHandle
+                               with:out fileHandle
+                               with:err fileHandle
+                               with:auxFd)
+        fork:true
+        newPgrp:newPgrp
+        inDirectory:dir
+        showWindow:(showWindowBooleanOrNil ? (shellAndArgs at:3)).
 
     nullStream notNil ifTrue:[
-	nullStream close.
+        nullStream close.
     ].
 
     ^ pid
@@ -1013,7 +1015,7 @@
      The following will no longer work. monitorPid has disappeared
 
      pid notNil ifTrue:[
-	 Processor monitorPid:pid action:[:osStatus | sema signal ].
+         Processor monitorPid:pid action:[:osStatus | sema signal ].
      ].
      in close.
      out close.
@@ -1028,10 +1030,10 @@
      sema := Semaphore new.
 
      Processor
-	    monitor:[
-		pid := OperatingSystem startProcess:'(sleep 2; ls -l) > out 2>err'
-	    ]
-	    action:[:osStatus | sema signal ].
+            monitor:[
+                pid := OperatingSystem startProcess:'(sleep 2; ls -l) > out 2>err'
+            ]
+            action:[:osStatus | sema signal ].
 
      sema wait.
      Transcript showCR:'finished'
@@ -1043,10 +1045,10 @@
      sema := Semaphore new.
 
      Processor
-	    monitor:[
-		pid := OperatingSystem startProcess:'(sleep 1; echo 1; sleep 9; ls -l) > out 2>err'
-	    ]
-	    action:[:osStatus | sema signal ].
+            monitor:[
+                pid := OperatingSystem startProcess:'(sleep 1; echo 1; sleep 9; ls -l) > out 2>err'
+            ]
+            action:[:osStatus | sema signal ].
 
      Delay waitForSeconds:2.
      OperatingSystem terminateProcess:pid.
@@ -1077,7 +1079,7 @@
      The following will no longer work. monitorPid has disappeared
 
      pid notNil ifTrue:[
-	 Processor monitorPid:pid action:[:OSstatus | sema signal ].
+         Processor monitorPid:pid action:[:OSstatus | sema signal ].
      ].
      in close.
      out close.
@@ -1092,10 +1094,10 @@
      sema := Semaphore new.
 
      Processor
-	    monitor:[
-		pid := OperatingSystem startProcess:'dir > out 2>err'
-	    ]
-	    action:[:osStatus | sema signal ].
+            monitor:[
+                pid := OperatingSystem startProcess:'dir > out 2>err'
+            ]
+            action:[:osStatus | sema signal ].
 
      sema wait.
      Transcript showCR:'finished'
@@ -1107,10 +1109,10 @@
      sema := Semaphore new.
 
      Processor
-	    monitor:[
-		pid := OperatingSystem startProcess:'(echo 1 & stx --eval "Delay waitForSeconds:100" & dir) >out' withCRs
-	    ]
-	    action:[:osStatus | sema signal ].
+            monitor:[
+                pid := OperatingSystem startProcess:'(echo 1 & stx --eval "Delay waitForSeconds:100" & dir) >out' withCRs
+            ]
+            action:[:osStatus | sema signal ].
 
      Delay waitForSeconds:5.
      OperatingSystem terminateProcessGroup:pid.
@@ -1123,10 +1125,10 @@
      sema := Semaphore new.
 
      Processor
-	    monitor:[
-		pid := OperatingSystem startProcess:{ 'C:\Users\cg\work\stx\projects\smalltalk\stx.com' . '--eval' . '"Delay waitForSeconds:100"' }
-	    ]
-	    action:[:osStatus | sema signal ].
+            monitor:[
+                pid := OperatingSystem startProcess:{ 'C:\Users\cg\work\stx\projects\smalltalk\stx.com' . '--eval' . '"Delay waitForSeconds:100"' }
+            ]
+            action:[:osStatus | sema signal ].
 
      Delay waitForSeconds:5.
      OperatingSystem terminateProcess:pid.