diff --git a/.gitignore b/.gitignore
index 9c452a725..2cbccc983 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,6 +1,7 @@
 *.o
 *.a
 skynet
+skynet.pid
 3rd/lua/lua
 3rd/lua/luac
 cservice
diff --git a/Makefile b/Makefile
index 35f6626d1..9c84351d4 100644
--- a/Makefile
+++ b/Makefile
@@ -48,7 +48,7 @@ LUA_CLIB = skynet socketdriver int64 bson mongo md5 netpack \
 SKYNET_SRC = skynet_main.c skynet_handle.c skynet_module.c skynet_mq.c \
   skynet_server.c skynet_start.c skynet_timer.c skynet_error.c \
   skynet_harbor.c skynet_env.c skynet_monitor.c skynet_socket.c socket_server.c \
-  malloc_hook.c
+  malloc_hook.c skynet_daemon.c
 
 all : \
   $(SKYNET_BUILD_PATH)/skynet \
diff --git a/examples/config b/examples/config
index f759d57f1..2f621b830 100644
--- a/examples/config
+++ b/examples/config
@@ -12,4 +12,4 @@ lualoader = "lualib/loader.lua"
 -- preload = "./examples/preload.lua"	-- run preload.lua before every lua service run
 snax = root.."examples/?.lua;"..root.."test/?.lua"
 cpath = root.."cservice/?.so"
-daemon = false
+daemon = "./skynet.pid"
diff --git a/skynet-src/skynet_daemon.c b/skynet-src/skynet_daemon.c
new file mode 100644
index 000000000..6a557b764
--- /dev/null
+++ b/skynet-src/skynet_daemon.c
@@ -0,0 +1,97 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/file.h>
+#include <signal.h>
+#include <errno.h>
+
+#include "skynet_daemon.h"
+
+static int
+check_pid(const char *pidfile) {
+	int pid = 0;
+	FILE *f = fopen(pidfile,"r");
+	if (f == NULL)
+		return 0;
+	int n = fscanf(f,"%d", &pid);
+	fclose(f);
+
+	if (n !=1 || pid == 0 || pid == getpid()) {
+		return 0;
+	}
+
+	if (kill(pid, 0) && errno == ESRCH)
+		return 0;
+
+	return pid;
+}
+
+static int 
+write_pid(const char *pidfile) {
+	FILE *f;
+	int pid = 0;
+	int fd = open(pidfile, O_RDWR|O_CREAT, 0644);
+	if (fd == -1) {
+		fprintf(stderr, "Can't create %s.\n", pidfile);
+		return 0;
+	}
+	f = fdopen(fd, "r+");
+	if (f == NULL) {
+		fprintf(stderr, "Can't open %s.\n", pidfile);
+		return 0;
+	}
+
+	if (flock(fd, LOCK_EX|LOCK_NB) == -1) {
+		int n = fscanf(f, "%d", &pid);
+		fclose(f);
+		if (n != 1) {
+			fprintf(stderr, "Can't lock and read pidfile.\n");
+		} else {
+			fprintf(stderr, "Can't lock pidfile, lock is held by pid %d.\n", pid);
+		}
+		return 0;
+	}
+	
+	pid = getpid();
+	if (!fprintf(f,"%d\n", pid)) {
+		fprintf(stderr, "Can't write pid.\n");
+		close(fd);
+		return 0;
+	}
+	fflush(f);
+
+	if (flock(fd, LOCK_UN) == -1) {
+		fprintf(stderr, "Can't unlock pidfile %s.\n", pidfile);
+		close(fd);
+		return 0;
+	}
+	close(fd);
+
+	return pid;
+}
+
+int
+daemon_init(const char *pidfile) {
+	int pid = check_pid(pidfile);
+	if (pid) {
+		fprintf(stderr, "Skynet is already running, pid = %d.\n", pid);
+		return 1;
+	}
+
+	if (daemon(1,0)) {
+		fprintf(stderr, "Can't daemonize.\n");
+		return 1;
+	}
+
+	pid = write_pid(pidfile);
+	if (pid == 0) {
+		return 1;
+	}
+
+	return 0;
+}
+
+int 
+daemon_exit(const char *pidfile) {
+	return unlink (pidfile);
+}
diff --git a/skynet-src/skynet_daemon.h b/skynet-src/skynet_daemon.h
new file mode 100644
index 000000000..0d99562a1
--- /dev/null
+++ b/skynet-src/skynet_daemon.h
@@ -0,0 +1,7 @@
+#ifndef skynet_daemon_h
+#define skynet_daemon_h
+
+int daemon_init(const char *pidfile);
+int daemon_exit(const char *pidfile);
+
+#endif
diff --git a/skynet-src/skynet_imp.h b/skynet-src/skynet_imp.h
index afad0305c..11b12ee10 100644
--- a/skynet-src/skynet_imp.h
+++ b/skynet-src/skynet_imp.h
@@ -4,7 +4,7 @@
 struct skynet_config {
 	int thread;
 	int harbor;
-	int daemon;
+	const char * daemon;
 	const char * module_path;
 	const char * bootstrap;
 };
diff --git a/skynet-src/skynet_main.c b/skynet-src/skynet_main.c
index 49f5ed3ce..8596c7786 100644
--- a/skynet-src/skynet_main.c
+++ b/skynet-src/skynet_main.c
@@ -24,6 +24,7 @@ optint(const char *key, int opt) {
 	return strtol(str, NULL, 10);
 }
 
+/*
 static int
 optboolean(const char *key, int opt) {
 	const char * str = skynet_getenv(key);
@@ -33,6 +34,7 @@ optboolean(const char *key, int opt) {
 	}
 	return strcmp(str,"true")==0;
 }
+*/
 
 static const char *
 optstring(const char *key,const char * opt) {
@@ -112,7 +114,7 @@ main(int argc, char *argv[]) {
 	config.module_path = optstring("cpath","./cservice/?.so");
 	config.harbor = optint("harbor", 1);
 	config.bootstrap = optstring("bootstrap","snlua bootstrap");
-	config.daemon = optboolean("daemon", 0);
+	config.daemon = optstring("daemon", NULL);
 
 	lua_close(L);
 
diff --git a/skynet-src/skynet_start.c b/skynet-src/skynet_start.c
index 91b4f2240..09ab7711f 100644
--- a/skynet-src/skynet_start.c
+++ b/skynet-src/skynet_start.c
@@ -7,6 +7,7 @@
 #include "skynet_timer.h"
 #include "skynet_monitor.h"
 #include "skynet_socket.h"
+#include "skynet_daemon.h"
 
 #include <pthread.h>
 #include <unistd.h>
@@ -196,8 +197,7 @@ bootstrap(const char * cmdline) {
 void 
 skynet_start(struct skynet_config * config) {
 	if (config->daemon) {
-		if (daemon(1,0)) {
-			fprintf(stderr, "daemon error");
+		if (daemon_init(config->daemon)) {
 			exit(1);
 		}
 	}
@@ -212,4 +212,7 @@ skynet_start(struct skynet_config * config) {
 
 	_start(config->thread);
 	skynet_socket_free();
+	if (config->daemon) {
+		daemon_exit(config->daemon);
+	}
 }