diff --git a/src/core/ev.c b/src/core/ev.c
index 42b599f1..5f733c9e 100644
--- a/src/core/ev.c
+++ b/src/core/ev.c
@@ -2004,7 +2004,6 @@ error:
 
 static void janet_ev_go(JanetFiber *fiber, Janet value, JanetChannel *supervisor_channel) {
     fiber->supervisor_channel = supervisor_channel;
-    /* janet_channel_push(supervisor_channel, make_supervisor_event("new", fiber), 2); */
     janet_schedule(fiber, value);
 }
 
@@ -2031,6 +2030,17 @@ static Janet cfun_ev_call(int32_t argc, Janet *argv) {
     return janet_wrap_fiber(fiber);
 }
 
+static Janet cfun_ev_give_supervisor(int32_t argc, Janet *argv) {
+    janet_arity(argc, 1, -1);
+    JanetChannel *chan = janet_vm_root_fiber->supervisor_channel;
+    if (NULL != chan) {
+        if (janet_channel_push(chan, janet_wrap_tuple(janet_tuple_n(argv, argc)), 0)) {
+            janet_await();
+        }
+    }
+    return janet_wrap_nil();
+}
+
 JANET_NO_RETURN void janet_sleep_await(double sec) {
     JanetTimeout to;
     to.when = ts_delta(ts_now(), sec);
@@ -2139,6 +2149,13 @@ static const JanetReg ev_cfuns[] = {
              "events occur in the newly scheduled fiber, an event will be pushed to the supervisor. "
              "If not provided, the new fiber will inherit the current supervisor.")
     },
+    {
+        "ev/give-supervisor", cfun_ev_give_supervisor,
+        JDOC("(ev/give-supervsior tag & payload)\n\n"
+             "Send a message to the current supervior channel if there is one. The message will be a "
+             "tuple of all of the arguments combined into a single message, where the first element is tag. "
+             "By convention, tag should be a keyword indicating the type of message. Returns nil.")
+    },
     {
         "ev/sleep", cfun_ev_sleep,
         JDOC("(ev/sleep sec)\n\n"
diff --git a/src/core/fiber.c b/src/core/fiber.c
index 03576021..e124873f 100644
--- a/src/core/fiber.c
+++ b/src/core/fiber.c
@@ -602,7 +602,10 @@ static const JanetReg fiber_cfuns[] = {
              "Create a new fiber with function body func. Can optionally "
              "take a set of signals to block from the current parent fiber "
              "when called. The mask is specified as a keyword where each character "
-             "is used to indicate a signal to block. The default sigmask is :y. "
+             "is used to indicate a signal to block. If the ev module is enabled, and "
+             "this fiber is used as an argument to `ev/go`, these \"blocked\" signals "
+             "will result in messages being sent to the supervisor channel. "
+             "The default sigmask is :y. "
              "For example,\n\n"
              "    (fiber/new myfun :e123)\n\n"
              "blocks error signals and user signals 1, 2 and 3. The signals are "
diff --git a/src/core/os.c b/src/core/os.c
index 510d9b24..e6e53ca5 100644
--- a/src/core/os.c
+++ b/src/core/os.c
@@ -322,6 +322,9 @@ static const JanetAbstractType ProcAT;
 #define JANET_PROC_WAITED 2
 #define JANET_PROC_WAITING 4
 #define JANET_PROC_ERROR_NONZERO 8
+#define JANET_PROC_OWNS_STDIN 16
+#define JANET_PROC_OWNS_STDOUT 32
+#define JANET_PROC_OWNS_STDERR 64
 typedef struct {
     int flags;
 #ifdef JANET_WINDOWS
@@ -889,12 +892,9 @@ static Janet os_execute_impl(int32_t argc, Janet *argv, int is_spawn) {
     }
 
     /* Wait for child */
+    os_execute_cleanup(envp, child_argv);
     if (status) {
-        os_execute_cleanup(envp, child_argv);
         janet_panicf("%p: %s", argv[0], strerror(errno));
-    } else {
-        /* Wait to complete */
-        os_execute_cleanup(envp, child_argv);
     }
 
 #endif
@@ -909,24 +909,24 @@ static Janet os_execute_impl(int32_t argc, Janet *argv, int is_spawn) {
     proc->in = NULL;
     proc->out = NULL;
     proc->err = NULL;
-    if (new_in != JANET_HANDLE_NONE) {
-        proc->in = get_stdio_for_handle(new_in, orig_in, 1);
-        if (NULL == proc->in) janet_panic("failed to construct proc");
-    }
-    if (new_out != JANET_HANDLE_NONE) {
-        proc->out = get_stdio_for_handle(new_out, orig_out, 0);
-        if (NULL == proc->out) janet_panic("failed to construct proc");
-    }
-    if (new_err != JANET_HANDLE_NONE) {
-        proc->err = get_stdio_for_handle(new_err, orig_err, 0);
-        if (NULL == proc->err) janet_panic("failed to construct proc");
-    }
     proc->flags = 0;
     if (janet_flag_at(flags, 2)) {
         proc->flags |= JANET_PROC_ERROR_NONZERO;
     }
-
     if (is_spawn) {
+        /* Only set up pointers to stdin, stdout, and stderr if os/spawn. */
+        if (new_in != JANET_HANDLE_NONE) {
+            proc->in = get_stdio_for_handle(new_in, orig_in, 1);
+            if (NULL == proc->in) janet_panic("failed to construct proc");
+        }
+        if (new_out != JANET_HANDLE_NONE) {
+            proc->out = get_stdio_for_handle(new_out, orig_out, 0);
+            if (NULL == proc->out) janet_panic("failed to construct proc");
+        }
+        if (new_err != JANET_HANDLE_NONE) {
+            proc->err = get_stdio_for_handle(new_err, orig_err, 0);
+            if (NULL == proc->err) janet_panic("failed to construct proc");
+        }
         return janet_wrap_abstract(proc);
     } else {
 #ifdef JANET_EV
diff --git a/test/suite0009.janet b/test/suite0009.janet
index df4fb2ac..1a236f22 100644
--- a/test/suite0009.janet
+++ b/test/suite0009.janet
@@ -74,6 +74,25 @@
       (calc-2 "(+ 9 10 11 12)"))
     @[10 26 42]) "parallel subprocesses 2")
 
+# File piping
+
+(assert-no-error "file writing 1"
+  (with [f (file/temp)]
+    (os/execute [janet "-e" `(repeat 20 (print :hello))`] :p {:out f})))
+
+(assert-no-error "file writing 2"
+  (with [f (file/open "unique.txt" :w)]
+    (os/execute [janet "-e" `(repeat 20 (print :hello))`] :p {:out f})
+    (file/flush f)))
+
+# Issue #593
+(assert-no-error "file writing 3"
+  (def outfile (file/open "unique.txt" :w))
+  (os/execute [janet "-e" "(pp (seq [i :range (1 10)] i))"] :p {:out outfile})
+  (file/flush outfile)
+  (file/close outfile)
+  (os/rm "unique.txt"))
+
 # ev/gather
 
 (assert (deep= @[1 2 3] (ev/gather 1 2 3)) "ev/gather 1")