diff --git a/src/nasal_codegen.h b/src/nasal_codegen.h
index ab742c9..8b4d123 100644
--- a/src/nasal_codegen.h
+++ b/src/nasal_codegen.h
@@ -60,9 +60,8 @@ private:
         "__pipe", "__fork", "__waitpid", "__chdir",
         "__environ", "__getcwd", "__getenv",
         // subprocess
-        "__subprocess_popen",
-        "__subprocess_pclose",
-        "__subprocess_read_stdout"
+        "__subprocess_create",
+        "__subprocess_terminate"
     };
 
     // file mapper for file -> index
diff --git a/src/nasal_import.cpp b/src/nasal_import.cpp
index 4093516..77a206e 100644
--- a/src/nasal_import.cpp
+++ b/src/nasal_import.cpp
@@ -9,8 +9,15 @@
 namespace nasal {
 
 linker::linker(): show_path_flag(false), this_file("") {
+    const auto env_get_path = getenv("PATH");
+    if (!env_get_path) {
+        err.warn("link", "cannot get env \"PATH\".");
+        envpath = {};
+        return;
+    }
+
     const auto seperator = util::is_windows()? ';':':';
-    const auto PATH = std::string(getenv("PATH"));
+    const auto PATH = std::string(env_get_path);
     usize last = 0, position = PATH.find(seperator, 0);
     while(position!=std::string::npos) {
         std::string dirpath = PATH.substr(last, position-last);
diff --git a/src/natives/subprocess.cpp b/src/natives/subprocess.cpp
index f6974e0..a04038e 100644
--- a/src/natives/subprocess.cpp
+++ b/src/natives/subprocess.cpp
@@ -4,65 +4,187 @@
 #ifdef _MSC_VER
 #define popen _popen
 #define pclose _pclose
+#define perror _perror
+#endif
+
+#ifndef _MSC_VER
+#include <unistd.h>
+#endif
+
+#ifndef WIN32
+#include <sys/wait.h>
 #endif
 
 #include <cstdio>
+#include <cstdlib>
+#include <cwchar>
+#include <clocale>
+#include <vector>
+#include <csignal>
 
 namespace nasal {
 
-const auto subprocess_object_name = "subprocess";
+const auto subproc_desc_name = "subprocess_descriptor";
 
-void subprocess_destructor(void* ptr) {
-    pclose(static_cast<FILE*>(ptr));
+void subprocess_desc_dtor(void* ptr) {
+#ifdef WIN32
+    auto pi = &static_cast<subprocess_descriptor*>(ptr)->pi;
+
+    WaitForSingleObject(pi->hProcess, 0);
+    TerminateProcess(pi->hProcess, 0);
+    CloseHandle(pi->hProcess);
+    CloseHandle(pi->hThread);
+#else
+    auto pid = static_cast<subprocess_descriptor*>(ptr)->pid;
+
+    int status;
+    pid_t result = waitpid(pid, &status, WNOHANG);
+
+    // child process running
+    if (result==0) {
+        kill(pid, SIGTERM);
+    }
+#endif
 }
 
-var builtin_subprocess_popen(context* ctx, gc* ngc) {
-    auto command = ctx->localr[1];
-    if (!command.is_str()) {
-        return nas_err("subprocess::popen", "expect a string as the command");
+var builtin_subprocess_create(context* ctx, gc* ngc) {
+    auto cmd = ctx->localr[1];
+    if (!cmd.is_vec()) {
+        return nas_err("subprocess::create", "expect a string as the command");
     }
 
-    auto fd = popen(command.str().c_str(), "r");
-    if (fd == nullptr) {
-        return nas_err("subprocess::popen", "failed to create sub-process");
+    for(const auto& v : cmd.vec().elems) {
+        if (!v.is_str()) {
+            return nas_err("subprocess::create", "non-string arguments");
+        }
     }
 
-    var ret = ngc->alloc(vm_type::vm_ghost);
-    ret.ghost().set(subprocess_object_name, subprocess_destructor, nullptr, fd);
-    return ret;
+    auto obj = ngc->alloc(vm_type::vm_ghost);
+    obj.ghost().set(
+        subproc_desc_name,
+        subprocess_desc_dtor,
+        nullptr,
+        new subprocess_descriptor
+    );
+
+#ifdef WIN32
+    auto si = &static_cast<subprocess_descriptor*>(obj.ghost().pointer)->si;
+    auto pi = &static_cast<subprocess_descriptor*>(obj.ghost().pointer)->pi;
+
+    // init STARTUPINFO
+    ZeroMemory(si, sizeof(STARTUPINFOW));
+    si->cb = sizeof(STARTUPINFOW);
+    si->dwFlags = STARTF_USESHOWWINDOW;
+    si->wShowWindow = SW_SHOW;
+
+    // init PROCESS_INFORMATION
+    ZeroMemory(pi, sizeof(PROCESS_INFORMATION));
+
+    auto command = cmd.vec().elems[0].str();
+    for(usize i = 1; i<cmd.vec().elems.size(); ++i) {
+        command += " " + cmd.vec().elems[i].str();
+    }
+
+    std::setlocale(LC_ALL, ".UTF8");
+    auto str_length = 1 + (command.length()<<1);
+    auto buffer = new wchar_t[str_length];
+    auto converted = mbstowcs(buffer, command.c_str(), str_length);
+    if (converted == size_t(-1)) {
+        delete[] buffer;
+        return nas_err("subprocess::create", "failed to convert wchat_t*");
+    }
+
+    buffer[converted] = L'\0';
+
+    if (!CreateProcessW(
+        nullptr,
+        buffer,
+        nullptr,
+        nullptr,
+        false,
+        0,
+        nullptr,
+        nullptr,
+        si,
+        pi
+    )) {
+        return nas_err("subprocess::create",
+            "failed to create subprocess: " +
+            std::to_string(GetLastError())
+        );
+    }
+    delete[] buffer;
+#else
+    // create argv
+    char** argv = new char*[cmd.vec().elems.size()+1];
+    for(usize i = 0; i<cmd.vec().elems.size(); ++i) {
+        argv[i] = strdup(cmd.vec().elems[i].str().c_str());
+    }
+    argv[cmd.vec().elems.size()] = nullptr;
+
+    // create child process
+    auto pid = fork();
+    if (pid < 0) {
+        return nas_err("subprocess::create", "failed to create sub-process");
+    }
+    // child process
+    if (pid==0) {
+        execvp(argv[0], argv);
+        nas_err("subprocess::create", "failed to execute command");
+        _exit(-1);
+    }
+
+    // parent process
+    static_cast<subprocess_descriptor*>(obj.ghost().pointer)->pid = pid;
+    for(usize i = 0; argv[i]; ++i) {
+        delete argv[i];
+    }
+    delete[] argv;
+
+#endif
+
+    return obj;
 }
 
-var builtin_subprocess_pclose(context* ctx, gc* ngc) {
-    auto fd = ctx->localr[1];
-    if (!fd.object_check(subprocess_object_name)) {
-        return nas_err("subprocess::pclose", "not a valid subprocess");
+var builtin_subprocess_terminate(context* ctx, gc* ngc) {
+    auto obj = ctx->localr[1];
+    if (!obj.object_check(subproc_desc_name)) {
+        return nas_err("subprocess::terminate",
+            "need correct subprocess descriptor"
+        );
     }
-    auto res = pclose(static_cast<FILE*>(fd.ghost().pointer));
-    fd.ghost().pointer = nullptr;
-    fd.ghost().clear();
+
+#ifdef WIN32
+    auto pi = &static_cast<subprocess_descriptor*>(obj.ghost().pointer)->pi;
+
+    WaitForSingleObject(pi->hProcess, 0);
+    TerminateProcess(pi->hProcess, -1);
+
+    DWORD res;
+    GetExitCodeProcess(pi->hProcess, &res);
+
+    CloseHandle(pi->hProcess);
+    CloseHandle(pi->hThread);
+#else
+    auto pid = static_cast<subprocess_descriptor*>(obj.ghost().pointer)->pid;
+
+    int status;
+    pid_t result = waitpid(pid, &status, WNOHANG);
+
+    // child process running
+    if (result==0) {
+        kill(pid, SIGTERM);
+    }
+
+    auto res = WIFEXITED(status)? WEXITSTATUS(status):-1;
+#endif
+
     return var::num(res);
 }
 
-var builtin_subprocess_read_stdout(context* ctx, gc* ngc) {
-    auto fd = ctx->localr[1];
-    if (!fd.object_check(subprocess_object_name)) {
-        return nas_err("subprocess::pclose", "not a valid subprocess");
-    }
-    char buffer[1025];
-    auto res = ngc->alloc(vm_type::vm_str);
-    while(fgets(
-        buffer,
-        sizeof(buffer)-1,
-        static_cast<FILE*>(fd.ghost().pointer))!=nullptr) {
-        res.str() += buffer;
-    }
-    return res;
-}
-
 nasal_builtin_table subprocess_native[] = {
-    {"__subprocess_popen", builtin_subprocess_popen},
-    {"__subprocess_pclose", builtin_subprocess_pclose},
-    {"__subprocess_read_stdout", builtin_subprocess_read_stdout},
+    {"__subprocess_create", builtin_subprocess_create},
+    {"__subprocess_terminate", builtin_subprocess_terminate},
     {nullptr, nullptr}
 };
 
diff --git a/src/natives/subprocess.h b/src/natives/subprocess.h
index 23029a4..4e25f19 100644
--- a/src/natives/subprocess.h
+++ b/src/natives/subprocess.h
@@ -4,13 +4,29 @@
 #include "nasal_gc.h"
 #include "natives/builtin.h"
 
+#ifndef _MSC_VER
+#include <unistd.h>
+#endif
+
+#ifndef WIN32
+#include <sys/wait.h>
+#endif
+
 namespace nasal {
 
-void subprocess_destructor(void*);
+struct subprocess_descriptor {
+#ifndef WIN32
+    pid_t pid;
+#else
+    STARTUPINFOW si;
+    PROCESS_INFORMATION pi;
+#endif
+};
 
-var builtin_subprocess_popen(context*, gc*);
-var builtin_subprocess_pclose(context*, gc*);
-var builtin_subprocess_read_stdout(context*, gc*);
+void subprocess_desc_dtor(void*);
+
+var builtin_subprocess_create(context*, gc*);
+var builtin_subprocess_terminate(context*, gc*);
 extern nasal_builtin_table subprocess_native[];
 
 }
\ No newline at end of file
diff --git a/std/dylib.nas b/std/dylib.nas
index a808653..a63b0a0 100644
--- a/std/dylib.nas
+++ b/std/dylib.nas
@@ -13,7 +13,7 @@ var dlopen = func(libname) {
     if (io.exists(libname))
         return __dlopen(libname);
     # find dynamic lib through PATH
-    var envpath = split(os.platform()=="windows"? ";":":",unix.getenv("PATH"));
+    var envpath = split(os.platform()=="windows"? ";":":", unix.getenv("PATH"));
     # first find ./module
     append(envpath, ".");
     var path = os.platform()=="windows"? "\\module\\":"/module/";
diff --git a/std/subprocess.nas b/std/subprocess.nas
index e82cf8b..f256ca8 100644
--- a/std/subprocess.nas
+++ b/std/subprocess.nas
@@ -1,11 +1,8 @@
-var popen = func(cmd) {
-    return __subprocess_popen(cmd);
+
+var create = func(vec) {
+    return __subprocess_create(vec);
 }
 
-var pclose = func(subproc) {
-    return __subprocess_pclose(subproc);
+var terminate = func(pid) {
+    return __subprocess_terminate(pid);
 }
-
-var read = func(subproc) {
-    return __subprocess_read_stdout(subproc);
-}
\ No newline at end of file
diff --git a/test/watchdog.nas b/test/watchdog.nas
index 5c3c32b..6b0658b 100644
--- a/test/watchdog.nas
+++ b/test/watchdog.nas
@@ -70,7 +70,7 @@ if (size(argv)==2) {
 var modified_time = io.fstat(filename).st_mtime;
 println(os_time(), info_hd(), "\e[1mwatching ", filename, " ..\e[0m");
 while(1) {
-    unix.sleep(5);
+    unix.sleep(1);
     if (!io.exists(filename)) {
         println(
             os_time(),
@@ -91,7 +91,6 @@ while(1) {
         foreach(var i; args) {
             cmd ~= " " ~ i;
         }
-        cmd ~= " 2>&1";
         println(
             os_time(),
             info_hd(),
@@ -100,12 +99,11 @@ while(1) {
             "\"\e[0m"
         );
 
-        var subproc = subprocess.popen(cmd);
-        var stdout_info = subprocess.read(subproc);
-        var ret = subprocess.pclose(subproc);
-        if (size(stdout_info)>0) {
-            println(stdout_info);
-        }
+        var subproc = subprocess.create(["nasal", filename]~args);
+
+        unix.sleep(2);
+        var ret = subprocess.terminate(subproc);
+
         println(
             os_time(),
             ret!=0? err_hd():info_hd(),