diff --git a/cmd-if-shell.c b/cmd-if-shell.c
index f7d95d53..0b1fe7f5 100644
--- a/cmd-if-shell.c
+++ b/cmd-if-shell.c
@@ -127,8 +127,8 @@ cmd_if_shell_exec(struct cmd *self, struct cmdq_item *item)
 		cdata->item = NULL;
 	memcpy(&cdata->mouse, &item->mouse, sizeof cdata->mouse);
 
-	job_run(shellcmd, s, cwd, cmd_if_shell_callback, cmd_if_shell_free,
-	    cdata);
+	job_run(shellcmd, s, cwd, NULL, cmd_if_shell_callback,
+	    cmd_if_shell_free, cdata);
 	free(shellcmd);
 
 	if (args_has(args, 'b'))
diff --git a/cmd-run-shell.c b/cmd-run-shell.c
index d06d7f99..48d88049 100644
--- a/cmd-run-shell.c
+++ b/cmd-run-shell.c
@@ -110,8 +110,8 @@ cmd_run_shell_exec(struct cmd *self, struct cmdq_item *item)
 	if (!args_has(args, 'b'))
 		cdata->item = item;
 
-	job_run(cdata->cmd, s, cwd, cmd_run_shell_callback, cmd_run_shell_free,
-	    cdata);
+	job_run(cdata->cmd, s, cwd, NULL, cmd_run_shell_callback,
+	    cmd_run_shell_free, cdata);
 
 	if (args_has(args, 'b'))
 		return (CMD_RETURN_NORMAL);
diff --git a/cmd-show-messages.c b/cmd-show-messages.c
index c88e0511..e7e56172 100644
--- a/cmd-show-messages.c
+++ b/cmd-show-messages.c
@@ -75,7 +75,7 @@ cmd_show_messages_jobs(struct cmdq_item *item, int blank)
 	u_int		 n;
 
 	n = 0;
-	LIST_FOREACH(job, &all_jobs, lentry) {
+	LIST_FOREACH(job, &all_jobs, entry) {
 		if (blank) {
 			cmdq_print(item, "%s", "");
 			blank = 0;
diff --git a/format.c b/format.c
index 839cf48a..5be10e1a 100644
--- a/format.c
+++ b/format.c
@@ -40,7 +40,6 @@
 struct format_entry;
 typedef void (*format_cb)(struct format_tree *, struct format_entry *);
 
-static void	 format_job_callback(struct job *);
 static char	*format_job_get(struct format_tree *, const char *);
 static void	 format_job_timer(int, short, void *);
 
@@ -76,7 +75,7 @@ static int	 format_replace(struct format_tree *, const char *, size_t,
 static void	 format_defaults_session(struct format_tree *,
 		     struct session *);
 static void	 format_defaults_client(struct format_tree *, struct client *);
-static void	 format_defaults_winlink(struct format_tree *, struct session *,
+static void	 format_defaults_winlink(struct format_tree *,
 		     struct winlink *);
 
 /* Entry in format job tree. */
@@ -87,6 +86,7 @@ struct format_job {
 
 	time_t			 last;
 	char			*out;
+	int			 updated;
 
 	struct job		*job;
 	int			 status;
@@ -207,9 +207,35 @@ static const char *format_lower[] = {
 	NULL		/* z */
 };
 
-/* Format job callback. */
+/* Format job update callback. */
 static void
-format_job_callback(struct job *job)
+format_job_update(struct job *job)
+{
+	struct format_job	*fj = job->data;
+	char			*line;
+	time_t			 t;
+	struct client		*c;
+
+	if ((line = evbuffer_readline(job->event->input)) == NULL)
+		return;
+	fj->updated = 1;
+
+	free(fj->out);
+	fj->out = line;
+
+	log_debug("%s: %s: %s", __func__, fj->cmd, fj->out);
+
+	t = time (NULL);
+	if (fj->status && fj->last != t) {
+		TAILQ_FOREACH(c, &clients, entry)
+		    server_status_client(c);
+		fj->last = t;
+	}
+}
+
+/* Format job complete callback. */
+static void
+format_job_complete(struct job *job)
 {
 	struct format_job	*fj = job->data;
 	char			*line, *buf;
@@ -217,7 +243,6 @@ format_job_callback(struct job *job)
 	struct client		*c;
 
 	fj->job = NULL;
-	free(fj->out);
 
 	buf = NULL;
 	if ((line = evbuffer_readline(job->event->input)) == NULL) {
@@ -228,15 +253,19 @@ format_job_callback(struct job *job)
 		buf[len] = '\0';
 	} else
 		buf = line;
-	fj->out = buf;
+
+	if (*buf != '\0' || !fj->updated) {
+		free(fj->out);
+		fj->out = buf;
+		log_debug("%s: %s: %s", __func__, fj->cmd, fj->out);
+	} else
+		free(buf);
 
 	if (fj->status) {
 		TAILQ_FOREACH(c, &clients, entry)
 		    server_status_client(c);
 		fj->status = 0;
 	}
-
-	log_debug("%s: %s: %s", __func__, fj->cmd, fj->out);
 }
 
 /* Find a job. */
@@ -271,8 +300,8 @@ format_job_get(struct format_tree *ft, const char *cmd)
 
 	t = time(NULL);
 	if (fj->job == NULL && (force || fj->last != t)) {
-		fj->job = job_run(expanded, NULL, NULL, format_job_callback,
-		    NULL, fj);
+		fj->job = job_run(expanded, NULL, NULL, format_job_update,
+		    format_job_complete, NULL, fj);
 		if (fj->job == NULL) {
 			free(fj->out);
 			xasprintf(&fj->out, "<'%s' didn't start>", fj->cmd);
@@ -1112,8 +1141,8 @@ format_defaults(struct format_tree *ft, struct client *c, struct session *s,
 		format_defaults_client(ft, c);
 	if (s != NULL)
 		format_defaults_session(ft, s);
-	if (s != NULL && wl != NULL)
-		format_defaults_winlink(ft, s, wl);
+	if (wl != NULL)
+		format_defaults_winlink(ft, wl);
 	if (wp != NULL)
 		format_defaults_pane(ft, wp);
 }
@@ -1224,21 +1253,18 @@ format_defaults_window(struct format_tree *ft, struct window *w)
 
 /* Set default format keys for a winlink. */
 static void
-format_defaults_winlink(struct format_tree *ft, struct session *s,
-    struct winlink *wl)
+format_defaults_winlink(struct format_tree *ft, struct winlink *wl)
 {
+	struct session	*s = wl->session;
 	struct window	*w = wl->window;
-	char		*flags;
 
 	if (ft->w == NULL)
 		ft->w = wl->window;
 
-	flags = window_printable_flags(s, wl);
-
 	format_defaults_window(ft, w);
 
 	format_add(ft, "window_index", "%d", wl->idx);
-	format_add(ft, "window_flags", "%s", flags);
+	format_add(ft, "window_flags", "%s", window_printable_flags(wl));
 	format_add(ft, "window_active", "%d", wl == s->curw);
 
 	format_add(ft, "window_bell_flag", "%d",
@@ -1250,8 +1276,6 @@ format_defaults_winlink(struct format_tree *ft, struct session *s,
 	format_add(ft, "window_last_flag", "%d",
 	    !!(wl == TAILQ_FIRST(&s->lastw)));
 	format_add(ft, "window_linked", "%d", session_is_linked(s, wl->window));
-
-	free(flags);
 }
 
 /* Set default format keys for a window pane. */
diff --git a/job.c b/job.c
index bf3b261a..1ed74e2a 100644
--- a/job.c
+++ b/job.c
@@ -32,8 +32,9 @@
  * output.
  */
 
-static void	job_callback(struct bufferevent *, short, void *);
+static void	job_read_callback(struct bufferevent *, void *);
 static void	job_write_callback(struct bufferevent *, void *);
+static void	job_error_callback(struct bufferevent *, short, void *);
 
 /* All jobs list. */
 struct joblist	all_jobs = LIST_HEAD_INITIALIZER(all_jobs);
@@ -41,7 +42,8 @@ struct joblist	all_jobs = LIST_HEAD_INITIALIZER(all_jobs);
 /* Start a job running, if it isn't already. */
 struct job *
 job_run(const char *cmd, struct session *s, const char *cwd,
-    void (*callbackfn)(struct job *), void (*freefn)(void *), void *data)
+    job_update_cb updatecb, job_complete_cb completecb, job_free_cb freecb,
+    void *data)
 {
 	struct job	*job;
 	struct environ	*env;
@@ -103,17 +105,18 @@ job_run(const char *cmd, struct session *s, const char *cwd,
 	job->pid = pid;
 	job->status = 0;
 
-	LIST_INSERT_HEAD(&all_jobs, job, lentry);
+	LIST_INSERT_HEAD(&all_jobs, job, entry);
 
-	job->callbackfn = callbackfn;
-	job->freefn = freefn;
+	job->updatecb = updatecb;
+	job->completecb = completecb;
+	job->freecb = freecb;
 	job->data = data;
 
 	job->fd = out[0];
 	setblocking(job->fd, 0);
 
-	job->event = bufferevent_new(job->fd, NULL, job_write_callback,
-	    job_callback, job);
+	job->event = bufferevent_new(job->fd, job_read_callback,
+	    job_write_callback, job_error_callback, job);
 	bufferevent_enable(job->event, EV_READ|EV_WRITE);
 
 	log_debug("run job %p: %s, pid %ld", job, job->cmd, (long) job->pid);
@@ -126,11 +129,11 @@ job_free(struct job *job)
 {
 	log_debug("free job %p: %s", job, job->cmd);
 
-	LIST_REMOVE(job, lentry);
+	LIST_REMOVE(job, entry);
 	free(job->cmd);
 
-	if (job->freefn != NULL && job->data != NULL)
-		job->freefn(job->data);
+	if (job->freecb != NULL && job->data != NULL)
+		job->freecb(job->data);
 
 	if (job->pid != -1)
 		kill(job->pid, SIGTERM);
@@ -142,7 +145,21 @@ job_free(struct job *job)
 	free(job);
 }
 
-/* Called when output buffer falls below low watermark (default is 0). */
+/* Job buffer read callback. */
+static void
+job_read_callback(__unused struct bufferevent *bufev, void *data)
+{
+	struct job	*job = data;
+
+	if (job->updatecb != NULL)
+		job->updatecb (job);
+}
+
+/*
+ * Job buffer write callback. Fired when the buffer falls below watermark
+ * (default is empty). If all the data has been written, disable the write
+ * event.
+ */
 static void
 job_write_callback(__unused struct bufferevent *bufev, void *data)
 {
@@ -160,7 +177,7 @@ job_write_callback(__unused struct bufferevent *bufev, void *data)
 
 /* Job buffer error callback. */
 static void
-job_callback(__unused struct bufferevent *bufev, __unused short events,
+job_error_callback(__unused struct bufferevent *bufev, __unused short events,
     void *data)
 {
 	struct job	*job = data;
@@ -168,8 +185,8 @@ job_callback(__unused struct bufferevent *bufev, __unused short events,
 	log_debug("job error %p: %s, pid %ld", job, job->cmd, (long) job->pid);
 
 	if (job->state == JOB_DEAD) {
-		if (job->callbackfn != NULL)
-			job->callbackfn(job);
+		if (job->completecb != NULL)
+			job->completecb(job);
 		job_free(job);
 	} else {
 		bufferevent_disable(job->event, EV_READ);
@@ -186,8 +203,8 @@ job_died(struct job *job, int status)
 	job->status = status;
 
 	if (job->state == JOB_CLOSED) {
-		if (job->callbackfn != NULL)
-			job->callbackfn(job);
+		if (job->completecb != NULL)
+			job->completecb(job);
 		job_free(job);
 	} else {
 		job->pid = -1;
diff --git a/server.c b/server.c
index 24e3ab61..0d8179fe 100644
--- a/server.c
+++ b/server.c
@@ -133,7 +133,8 @@ server_create_socket(void)
 int
 server_start(struct event_base *base, int lockfd, char *lockfile)
 {
-	int	pair[2];
+	int		 pair[2];
+	struct job	*job;
 
 	if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, pair) != 0)
 		fatal("socketpair failed");
@@ -179,6 +180,12 @@ server_start(struct event_base *base, int lockfd, char *lockfile)
 	server_add_accept(0);
 
 	proc_loop(server_proc, server_loop);
+
+	LIST_FOREACH(job, &all_jobs, entry) {
+		if (job->pid != -1)
+			kill(job->pid, SIGTERM);
+	}
+
 	status_prompt_save_history();
 	exit(0);
 }
@@ -399,7 +406,7 @@ server_child_exited(pid_t pid, int status)
 		}
 	}
 
-	LIST_FOREACH(job, &all_jobs, lentry) {
+	LIST_FOREACH(job, &all_jobs, entry) {
 		if (pid == job->pid) {
 			job_died(job, status);	/* might free job */
 			break;
diff --git a/tmux.1 b/tmux.1
index 63ae6436..86281194 100644
--- a/tmux.1
+++ b/tmux.1
@@ -3494,6 +3494,8 @@ does not wait for
 .Ql #()
 commands to finish; instead, the previous result from running the same command is used,
 or a placeholder if the command has not been run before.
+If the command hasn't exited, the most recent line of output will be used, but the status
+line will not be updated more than once a second.
 Commands are executed with the
 .Nm
 global environment set (see the
diff --git a/tmux.h b/tmux.h
index b84ba3cf..4b3385c6 100644
--- a/tmux.h
+++ b/tmux.h
@@ -592,6 +592,10 @@ struct hook {
 };
 
 /* Scheduled job. */
+struct job;
+typedef void (*job_update_cb) (struct job *);
+typedef void (*job_complete_cb) (struct job *);
+typedef void (*job_free_cb) (void *);
 struct job {
 	enum {
 		JOB_RUNNING,
@@ -599,18 +603,19 @@ struct job {
 		JOB_CLOSED
 	} state;
 
-	char		*cmd;
-	pid_t		 pid;
-	int		 status;
+	char			*cmd;
+	pid_t			 pid;
+	int			 status;
 
-	int		 fd;
-	struct bufferevent *event;
+	int			 fd;
+	struct bufferevent	*event;
 
-	void		(*callbackfn)(struct job *);
-	void		(*freefn)(void *);
-	void		*data;
+	job_update_cb		 updatecb;
+	job_complete_cb		 completecb;
+	job_free_cb		 freecb;
+	void			*data;
 
-	LIST_ENTRY(job)	 lentry;
+	LIST_ENTRY(job)	 	 entry;
 };
 LIST_HEAD(joblist, job);
 
@@ -1605,10 +1610,10 @@ extern const struct options_table_entry options_table[];
 
 /* job.c */
 extern struct joblist all_jobs;
-struct job *job_run(const char *, struct session *, const char *,
-	    void (*)(struct job *), void (*)(void *), void *);
-void	job_free(struct job *);
-void	job_died(struct job *, int);
+struct job	*job_run(const char *, struct session *, const char *,
+		     job_update_cb, job_complete_cb, job_free_cb, void *);
+void		 job_free(struct job *);
+void		 job_died(struct job *, int);
 
 /* environ.c */
 struct environ *environ_create(void);
@@ -2119,7 +2124,7 @@ int		 window_pane_outside(struct window_pane *);
 int		 window_pane_visible(struct window_pane *);
 char		*window_pane_search(struct window_pane *, const char *,
 		     u_int *);
-char		*window_printable_flags(struct session *, struct winlink *);
+const char	*window_printable_flags(struct winlink *);
 struct window_pane *window_pane_find_up(struct window_pane *);
 struct window_pane *window_pane_find_down(struct window_pane *);
 struct window_pane *window_pane_find_left(struct window_pane *);
diff --git a/window-copy.c b/window-copy.c
index 9b13926e..0896479a 100644
--- a/window-copy.c
+++ b/window-copy.c
@@ -1641,7 +1641,7 @@ window_copy_copy_pipe(struct window_pane *wp, struct session *s,
 		return;
 	expanded = format_single(NULL, arg, NULL, s, NULL, wp);
 
-	job = job_run(expanded, s, NULL, NULL, NULL, NULL);
+	job = job_run(expanded, s, NULL, NULL, NULL, NULL, NULL);
 	bufferevent_write(job->event, buf, len);
 
 	free(expanded);
diff --git a/window.c b/window.c
index e7a0aa52..dc2fddbb 100644
--- a/window.c
+++ b/window.c
@@ -709,12 +709,12 @@ window_destroy_panes(struct window *w)
 	}
 }
 
-/* Retuns the printable flags on a window, empty string if no flags set. */
-char *
-window_printable_flags(struct session *s, struct winlink *wl)
+const char *
+window_printable_flags(struct winlink *wl)
 {
-	char	flags[32];
-	int	pos;
+	struct session	*s = wl->session;
+	static char	 flags[32];
+	int		 pos;
 
 	pos = 0;
 	if (wl->flags & WINLINK_ACTIVITY)
@@ -732,7 +732,7 @@ window_printable_flags(struct session *s, struct winlink *wl)
 	if (wl->window->flags & WINDOW_ZOOMED)
 		flags[pos++] = 'Z';
 	flags[pos] = '\0';
-	return (xstrdup(flags));
+	return (flags);
 }
 
 struct window_pane *