diff --git a/_cmptest/_osexec/exec.go b/_cmptest/osexec/exec.go
similarity index 100%
rename from _cmptest/_osexec/exec.go
rename to _cmptest/osexec/exec.go
diff --git a/internal/lib/os/exec/exec.go b/internal/lib/os/exec/exec.go
index c54ecc3e..8f9059dc 100644
--- a/internal/lib/os/exec/exec.go
+++ b/internal/lib/os/exec/exec.go
@@ -29,6 +29,8 @@ import (
 	"strings"
 	"syscall"
 	"time"
+
+	"github.com/goplus/llgo/internal/lib/internal/syscall/execenv"
 )
 
 // Error is returned by LookPath when it fails to classify a file as an
@@ -1089,7 +1091,6 @@ func minInt(a, b int) int {
 // would be run as it is currently configured. If an error occurs in computing
 // the environment, it is returned alongside the best-effort copy.
 func (c *Cmd) environ() ([]string, error) {
-	/* TODO(xsw):
 	var err error
 
 	env := c.Env
@@ -1128,8 +1129,6 @@ func (c *Cmd) environ() ([]string, error) {
 		err = dedupErr
 	}
 	return addCriticalEnv(env), err
-	*/
-	panic("todo: exec.Cmd.environ")
 }
 
 // Environ returns a copy of the environment in which the command would be run
diff --git a/internal/lib/os/file_posix.go b/internal/lib/os/file_posix.go
index 03f1806c..684ff5be 100644
--- a/internal/lib/os/file_posix.go
+++ b/internal/lib/os/file_posix.go
@@ -16,13 +16,10 @@ import (
 // be canceled and return immediately with an ErrClosed error.
 // Close will return an error if it has already been called.
 func (f *File) Close() error {
-	/*
-		if f == nil {
-			return ErrInvalid
-		}
-		return f.file.close()
-	*/
-	panic("todo: os.(*File).Close")
+	if f == nil {
+		return ErrInvalid
+	}
+	return f.close()
 }
 
 // pread reads len(b) bytes from the File starting at byte offset off.
diff --git a/internal/lib/os/file_unix.go b/internal/lib/os/file_unix.go
index 918890a0..fc75f0c1 100644
--- a/internal/lib/os/file_unix.go
+++ b/internal/lib/os/file_unix.go
@@ -250,6 +250,27 @@ func openFileNolog(name string, flag int, perm FileMode) (*File, error) {
 	return f, nil
 }
 
+func (file *File) close() error {
+	return syscall.Close(int(file.fd))
+	/* TODO(xsw):
+	if file.dirinfo != nil {
+		file.dirinfo.close()
+		file.dirinfo = nil
+	}
+	var err error
+	if e := file.pfd.Close(); e != nil {
+		if e == poll.ErrFileClosing {
+			e = ErrClosed
+		}
+		err = &PathError{Op: "close", Path: file.name, Err: e}
+	}
+
+	// no need for a finalizer anymore
+	runtime.SetFinalizer(file, nil)
+	return err
+	*/
+}
+
 func tempDir() string {
 	dir := Getenv("TMPDIR")
 	if dir == "" {
diff --git a/internal/lib/syscall/exec_libc2.go b/internal/lib/syscall/exec_libc2.go
index 4c45b80b..02237240 100644
--- a/internal/lib/syscall/exec_libc2.go
+++ b/internal/lib/syscall/exec_libc2.go
@@ -261,22 +261,17 @@ func forkAndExecInChild(argv0 *c.Char, argv, envv **c.Char, chroot, dir *c.Char,
 		if fd[i] == i {
 			// dup2(i, i) won't clear close-on-exec flag on Linux,
 			// probably not elsewhere either.
-			ret := os.Fcntl(c.Int(fd[i]), syscall.F_SETFD, 0)
-			if ret != 0 {
+			if ret := os.Fcntl(c.Int(fd[i]), syscall.F_SETFD, 0); ret != 0 {
 				err1 = Errno(ret)
 				goto childerror
 			}
 			continue
 		}
-		/* TODO(xsw):
 		// The new fd is created NOT close-on-exec,
-		// which is exactly what we want.
-		_, _, err1 = rawSyscall(abi.FuncPCABI0(libc_dup2_trampoline), uintptr(fd[i]), uintptr(i), 0)
-		if err1 != 0 {
+		if ret := os.Dup2(c.Int(fd[i]), c.Int(i)); ret != 0 {
+			err1 = Errno(ret)
 			goto childerror
 		}
-		*/
-		panic("todo: syscall.forkAndExecInChild - dup2")
 	}
 
 	// By convention, we don't close-on-exec the fds we are