diff --git a/.idea/kobalt.xml b/.idea/kobalt.xml
index c1b8abc..48b08b1 100644
--- a/.idea/kobalt.xml
+++ b/.idea/kobalt.xml
@@ -16,7 +16,7 @@
       <KobaltProjectSettings>
         <option name="autoDownloadKobalt" value="true" />
         <option name="externalProjectPath" value="$PROJECT_DIR$/example" />
-        <option name="kobaltHome" value="$USER_HOME$/.kobalt/wrapper/dist/kobalt-0.845" />
+        <option name="kobaltHome" value="$USER_HOME$/.kobalt/wrapper/dist/kobalt-0.846" />
         <option name="useAutoImport" value="true" />
       </KobaltProjectSettings>
     </option>
diff --git a/example/kobalt/src/Build.kt b/example/kobalt/src/Build.kt
index c0fe72f..20bbbf4 100644
--- a/example/kobalt/src/Build.kt
+++ b/example/kobalt/src/Build.kt
@@ -37,7 +37,7 @@ val p = project {
     }
 
     exec {
-        commandLine(args = arrayOf("ls", "-- a"), dir = "../libs", fail = arrayOf(Fail.EXIT))
-		commandLine(arrayOf("cmd", "/c", "echo", "Test"), os = arrayOf("Win"), fail = arrayOf(Fail.STDERR))
+        commandLine(args = listOf("ls", "-- a"), dir = "../libs", fail = setOf(Fail.STDERR, Fail.EXIT))
+		commandLine(listOf("cmd", "/c", "echo", "Test"), os = listOf("Win"), fail = setOf(Fail.STDERR, Fail.EXIT))
     }
 }
\ No newline at end of file
diff --git a/kobalt-exec.iml b/kobalt-exec.iml
index 3773968..4b91eb9 100644
--- a/kobalt-exec.iml
+++ b/kobalt-exec.iml
@@ -25,9 +25,9 @@
       </library>
     </orderEntry>
     <orderEntry type="module-library" scope="TEST">
-      <library name="Kobalt: org.testng:testng:jar:(0,]">
+      <library name="Kobalt: com.beust:jcommander:jar:1.48">
         <CLASSES>
-          <root url="jar://$USER_HOME$/.kobalt/repository/org/testng/testng/6.9.10/testng-6.9.10.jar!/" />
+          <root url="jar://$USER_HOME$/.kobalt/repository/com/beust/jcommander/1.48/jcommander-1.48.jar!/" />
         </CLASSES>
         <JAVADOC />
         <SOURCES />
@@ -43,9 +43,9 @@
       </library>
     </orderEntry>
     <orderEntry type="module-library" scope="TEST">
-      <library name="Kobalt: com.beust:jcommander:jar:1.48">
+      <library name="Kobalt: org.testng:testng:jar:(0,]">
         <CLASSES>
-          <root url="jar://$USER_HOME$/.kobalt/repository/com/beust/jcommander/1.48/jcommander-1.48.jar!/" />
+          <root url="jar://$USER_HOME$/.kobalt/repository/org/testng/testng/6.9.10/testng-6.9.10.jar!/" />
         </CLASSES>
         <JAVADOC />
         <SOURCES />
diff --git a/kobalt/wrapper/kobalt-wrapper.properties b/kobalt/wrapper/kobalt-wrapper.properties
index 0d4030d..0630fba 100644
--- a/kobalt/wrapper/kobalt-wrapper.properties
+++ b/kobalt/wrapper/kobalt-wrapper.properties
@@ -1 +1 @@
-kobalt.version=0.845
\ No newline at end of file
+kobalt.version=0.846
\ No newline at end of file
diff --git a/src/main/kotlin/net/thauvin/erik/kobalt/plugin/exec/ExecPlugin.kt b/src/main/kotlin/net/thauvin/erik/kobalt/plugin/exec/ExecPlugin.kt
index 78e9829..d1e81f2 100644
--- a/src/main/kotlin/net/thauvin/erik/kobalt/plugin/exec/ExecPlugin.kt
+++ b/src/main/kotlin/net/thauvin/erik/kobalt/plugin/exec/ExecPlugin.kt
@@ -83,21 +83,23 @@ class ExecPlugin : BasePlugin(), ITaskContributor {
                         pb.directory(loc)
                         val proc = pb.start()
                         val err = proc.waitFor(30, TimeUnit.SECONDS)
-                        val stdin = if (proc.inputStream.available() > 0) fromStream(proc.inputStream) else listOf()
-                        val stderr = if (proc.errorStream.available() > 0) fromStream(proc.errorStream) else listOf()
+                        val stdout = if (proc.inputStream.available() > 0) fromStream(proc.inputStream) else emptyList()
+                        val stderr = if (proc.errorStream.available() > 0) fromStream(proc.errorStream) else emptyList()
+
+                        val errMsg = "Program \"" + it.args.joinToString(" ") + "\" (in directory \"$dir\"): "
 
                         if (err == false) {
-                            error("Cannot run program \"" + it.args.joinToString(" ")
-                                    + "\" (in directory \"$dir\"): TIMEOUT")
-                        } else if (it.fail.contains(Fail.EXIT) && proc.exitValue() > 0) {
-                            error("Program \"" + it.args.joinToString(" ")
-                                    + "\" (in directory \"$dir\"): EXIT ${proc.exitValue()}")
-                        } else if (it.fail.contains(Fail.STDERR) && stderr.isNotEmpty()) {
-                            error("Program \"" + it.args.joinToString(" ") + "\" (in directory \"$dir\"): STDERR, "
-                                    + stderr[0] + "...")
-                        } else if (it.fail.contains(Fail.STDIN) && stdin.isNotEmpty()) {
-                            error("Program \"" + it.args.joinToString(" ") + "\" (in directory \"$dir\"): STDIN, "
-                                    + stdin[0] + "...")
+                            error(errMsg + "TIMEOUT")
+                        } else if (it.fail.isNotEmpty()) {
+                            val all = it.fail.contains(Fail.ALL)
+                            val output = it.fail.contains(Fail.OUTPUT)
+                            if ((all || it.fail.contains(Fail.EXIT)) && proc.exitValue() > 0) {
+                                error(errMsg + "EXIT ${proc.exitValue()}")
+                            } else if ((all || output || it.fail.contains(Fail.STDERR)) && stderr.isNotEmpty()) {
+                                error(errMsg + "STDERR, " + stderr[0])
+                            } else if ((all || output || it.fail.contains(Fail.STDOUT)) && stdout.isNotEmpty()) {
+                                error(errMsg + "STDOUT, " + stdout[0])
+                            }
                         }
 
                         success = true
@@ -133,18 +135,18 @@ class ExecPlugin : BasePlugin(), ITaskContributor {
 }
 
 enum class Fail() {
-    STDERR, STDIN, EXIT
+    ALL, STDERR, STDOUT, OUTPUT, EXIT
 }
 
-data class CommandLine(var args: Array<String> = emptyArray(), var dir: String = "",
-                       var os: Array<String> = emptyArray(), var fail: Array<Fail> = emptyArray())
+data class CommandLine(var args: List<String> = emptyList(), var dir: String = "",
+                       var os: List<String> = emptyList(), var fail: Set<Fail> = emptySet())
 
 data class ExecConfig(val project: Project) {
     val commandLines = arrayListOf<CommandLine>()
 
     @Directive
-    public fun commandLine(args: Array<String> = emptyArray(), dir: String = "", os: Array<String> = emptyArray(),
-                           fail: Array<Fail> = emptyArray()) {
+    public fun commandLine(args: List<String> = emptyList(), dir: String = "", os: List<String> = emptyList(),
+                           fail: Set<Fail> = emptySet()) {
         if (args.size > 0) commandLines.add(CommandLine(args, dir, os, fail))
     }
 }
@@ -156,4 +158,4 @@ fun Project.exec(init: ExecConfig.() -> Unit): ExecConfig {
         (Kobalt.findPlugin(ExecPlugin.NAME) as ExecPlugin).addExecConfig(name, this)
         return this
     }
-}
+}
\ No newline at end of file