diff --git a/internal/lib/os/exec/exec.go b/internal/lib/os/exec/exec.go
index 20d33d73..d56db4e7 100644
--- a/internal/lib/os/exec/exec.go
+++ b/internal/lib/os/exec/exec.go
@@ -18,5 +18,1221 @@ package exec
 
 // llgo:skipall
 import (
-	_ "unsafe"
+	"bytes"
+	"context"
+	"errors"
+	"io"
+	"os"
+	"path/filepath"
+	"runtime"
+	"strconv"
+	"strings"
+	"syscall"
+	"time"
 )
+
+// Error is returned by LookPath when it fails to classify a file as an
+// executable.
+type Error struct {
+	// Name is the file name for which the error occurred.
+	Name string
+	// Err is the underlying error.
+	Err error
+}
+
+func (e *Error) Error() string {
+	return "exec: " + strconv.Quote(e.Name) + ": " + e.Err.Error()
+}
+
+func (e *Error) Unwrap() error { return e.Err }
+
+// ErrWaitDelay is returned by (*Cmd).Wait if the process exits with a
+// successful status code but its output pipes are not closed before the
+// command's WaitDelay expires.
+var ErrWaitDelay = errors.New("exec: WaitDelay expired before I/O complete")
+
+// wrappedError wraps an error without relying on fmt.Errorf.
+type wrappedError struct {
+	prefix string
+	err    error
+}
+
+func (w wrappedError) Error() string {
+	return w.prefix + ": " + w.err.Error()
+}
+
+func (w wrappedError) Unwrap() error {
+	return w.err
+}
+
+// Cmd represents an external command being prepared or run.
+//
+// A Cmd cannot be reused after calling its Run, Output or CombinedOutput
+// methods.
+type Cmd struct {
+	// Path is the path of the command to run.
+	//
+	// This is the only field that must be set to a non-zero
+	// value. If Path is relative, it is evaluated relative
+	// to Dir.
+	Path string
+
+	// Args holds command line arguments, including the command as Args[0].
+	// If the Args field is empty or nil, Run uses {Path}.
+	//
+	// In typical use, both Path and Args are set by calling Command.
+	Args []string
+
+	// Env specifies the environment of the process.
+	// Each entry is of the form "key=value".
+	// If Env is nil, the new process uses the current process's
+	// environment.
+	// If Env contains duplicate environment keys, only the last
+	// value in the slice for each duplicate key is used.
+	// As a special case on Windows, SYSTEMROOT is always added if
+	// missing and not explicitly set to the empty string.
+	Env []string
+
+	// Dir specifies the working directory of the command.
+	// If Dir is the empty string, Run runs the command in the
+	// calling process's current directory.
+	Dir string
+
+	// Stdin specifies the process's standard input.
+	//
+	// If Stdin is nil, the process reads from the null device (os.DevNull).
+	//
+	// If Stdin is an *os.File, the process's standard input is connected
+	// directly to that file.
+	//
+	// Otherwise, during the execution of the command a separate
+	// goroutine reads from Stdin and delivers that data to the command
+	// over a pipe. In this case, Wait does not complete until the goroutine
+	// stops copying, either because it has reached the end of Stdin
+	// (EOF or a read error), or because writing to the pipe returned an error,
+	// or because a nonzero WaitDelay was set and expired.
+	Stdin io.Reader
+
+	// Stdout and Stderr specify the process's standard output and error.
+	//
+	// If either is nil, Run connects the corresponding file descriptor
+	// to the null device (os.DevNull).
+	//
+	// If either is an *os.File, the corresponding output from the process
+	// is connected directly to that file.
+	//
+	// Otherwise, during the execution of the command a separate goroutine
+	// reads from the process over a pipe and delivers that data to the
+	// corresponding Writer. In this case, Wait does not complete until the
+	// goroutine reaches EOF or encounters an error or a nonzero WaitDelay
+	// expires.
+	//
+	// If Stdout and Stderr are the same writer, and have a type that can
+	// be compared with ==, at most one goroutine at a time will call Write.
+	Stdout io.Writer
+	Stderr io.Writer
+
+	// ExtraFiles specifies additional open files to be inherited by the
+	// new process. It does not include standard input, standard output, or
+	// standard error. If non-nil, entry i becomes file descriptor 3+i.
+	//
+	// ExtraFiles is not supported on Windows.
+	ExtraFiles []*os.File
+
+	// SysProcAttr holds optional, operating system-specific attributes.
+	// Run passes it to os.StartProcess as the os.ProcAttr's Sys field.
+	SysProcAttr *syscall.SysProcAttr
+
+	// Process is the underlying process, once started.
+	Process *os.Process
+
+	// ProcessState contains information about an exited process.
+	// If the process was started successfully, Wait or Run will
+	// populate its ProcessState when the command completes.
+	ProcessState *os.ProcessState
+
+	// ctx is the context passed to CommandContext, if any.
+	ctx context.Context
+
+	Err error // LookPath error, if any.
+
+	// If Cancel is non-nil, the command must have been created with
+	// CommandContext and Cancel will be called when the command's
+	// Context is done. By default, CommandContext sets Cancel to
+	// call the Kill method on the command's Process.
+	//
+	// Typically a custom Cancel will send a signal to the command's
+	// Process, but it may instead take other actions to initiate cancellation,
+	// such as closing a stdin or stdout pipe or sending a shutdown request on a
+	// network socket.
+	//
+	// If the command exits with a success status after Cancel is
+	// called, and Cancel does not return an error equivalent to
+	// os.ErrProcessDone, then Wait and similar methods will return a non-nil
+	// error: either an error wrapping the one returned by Cancel,
+	// or the error from the Context.
+	// (If the command exits with a non-success status, or Cancel
+	// returns an error that wraps os.ErrProcessDone, Wait and similar methods
+	// continue to return the command's usual exit status.)
+	//
+	// If Cancel is set to nil, nothing will happen immediately when the command's
+	// Context is done, but a nonzero WaitDelay will still take effect. That may
+	// be useful, for example, to work around deadlocks in commands that do not
+	// support shutdown signals but are expected to always finish quickly.
+	//
+	// Cancel will not be called if Start returns a non-nil error.
+	Cancel func() error
+
+	// If WaitDelay is non-zero, it bounds the time spent waiting on two sources
+	// of unexpected delay in Wait: a child process that fails to exit after the
+	// associated Context is canceled, and a child process that exits but leaves
+	// its I/O pipes unclosed.
+	//
+	// The WaitDelay timer starts when either the associated Context is done or a
+	// call to Wait observes that the child process has exited, whichever occurs
+	// first. When the delay has elapsed, the command shuts down the child process
+	// and/or its I/O pipes.
+	//
+	// If the child process has failed to exit — perhaps because it ignored or
+	// failed to receive a shutdown signal from a Cancel function, or because no
+	// Cancel function was set — then it will be terminated using os.Process.Kill.
+	//
+	// Then, if the I/O pipes communicating with the child process are still open,
+	// those pipes are closed in order to unblock any goroutines currently blocked
+	// on Read or Write calls.
+	//
+	// If pipes are closed due to WaitDelay, no Cancel call has occurred,
+	// and the command has otherwise exited with a successful status, Wait and
+	// similar methods will return ErrWaitDelay instead of nil.
+	//
+	// If WaitDelay is zero (the default), I/O pipes will be read until EOF,
+	// which might not occur until orphaned subprocesses of the command have
+	// also closed their descriptors for the pipes.
+	WaitDelay time.Duration
+
+	// childIOFiles holds closers for any of the child process's
+	// stdin, stdout, and/or stderr files that were opened by the Cmd itself
+	// (not supplied by the caller). These should be closed as soon as they
+	// are inherited by the child process.
+	childIOFiles []io.Closer
+
+	// parentIOPipes holds closers for the parent's end of any pipes
+	// connected to the child's stdin, stdout, and/or stderr streams
+	// that were opened by the Cmd itself (not supplied by the caller).
+	// These should be closed after Wait sees the command and copying
+	// goroutines exit, or after WaitDelay has expired.
+	parentIOPipes []io.Closer
+
+	// goroutine holds a set of closures to execute to copy data
+	// to and/or from the command's I/O pipes.
+	goroutine []func() error
+
+	// If goroutineErr is non-nil, it receives the first error from a copying
+	// goroutine once all such goroutines have completed.
+	// goroutineErr is set to nil once its error has been received.
+	goroutineErr <-chan error
+
+	// If ctxResult is non-nil, it receives the result of watchCtx exactly once.
+	ctxResult <-chan ctxResult
+
+	// The stack saved when the Command was created, if GODEBUG contains
+	// execwait=2. Used for debugging leaks.
+	createdByStack []byte
+
+	// For a security release long ago, we created x/sys/execabs,
+	// which manipulated the unexported lookPathErr error field
+	// in this struct. For Go 1.19 we exported the field as Err error,
+	// above, but we have to keep lookPathErr around for use by
+	// old programs building against new toolchains.
+	// The String and Start methods look for an error in lookPathErr
+	// in preference to Err, to preserve the errors that execabs sets.
+	//
+	// In general we don't guarantee misuse of reflect like this,
+	// but the misuse of reflect was by us, the best of various bad
+	// options to fix the security problem, and people depend on
+	// those old copies of execabs continuing to work.
+	// The result is that we have to leave this variable around for the
+	// rest of time, a compatibility scar.
+	//
+	// See https://go.dev/blog/path-security
+	// and https://go.dev/issue/43724 for more context.
+	lookPathErr error
+}
+
+// A ctxResult reports the result of watching the Context associated with a
+// running command (and sending corresponding signals if needed).
+type ctxResult struct {
+	err error
+
+	// If timer is non-nil, it expires after WaitDelay has elapsed after
+	// the Context is done.
+	//
+	// (If timer is nil, that means that the Context was not done before the
+	// command completed, or no WaitDelay was set, or the WaitDelay already
+	// expired and its effect was already applied.)
+	timer *time.Timer
+}
+
+/* TODO(xsw):
+var execwait = godebug.New("#execwait")
+var execerrdot = godebug.New("execerrdot")
+*/
+
+// Command returns the Cmd struct to execute the named program with
+// the given arguments.
+//
+// It sets only the Path and Args in the returned structure.
+//
+// If name contains no path separators, Command uses LookPath to
+// resolve name to a complete path if possible. Otherwise it uses name
+// directly as Path.
+//
+// The returned Cmd's Args field is constructed from the command name
+// followed by the elements of arg, so arg should not include the
+// command name itself. For example, Command("echo", "hello").
+// Args[0] is always name, not the possibly resolved Path.
+//
+// On Windows, processes receive the whole command line as a single string
+// and do their own parsing. Command combines and quotes Args into a command
+// line string with an algorithm compatible with applications using
+// CommandLineToArgvW (which is the most common way). Notable exceptions are
+// msiexec.exe and cmd.exe (and thus, all batch files), which have a different
+// unquoting algorithm. In these or other similar cases, you can do the
+// quoting yourself and provide the full command line in SysProcAttr.CmdLine,
+// leaving Args empty.
+func Command(name string, arg ...string) *Cmd {
+	cmd := &Cmd{
+		Path: name,
+		Args: append([]string{name}, arg...),
+	}
+
+	/* TODO(xsw):
+	if v := execwait.Value(); v != "" {
+		if v == "2" {
+			// Obtain the caller stack. (This is equivalent to runtime/debug.Stack,
+			// copied to avoid importing the whole package.)
+			stack := make([]byte, 1024)
+			for {
+				n := runtime.Stack(stack, false)
+				if n < len(stack) {
+					stack = stack[:n]
+					break
+				}
+				stack = make([]byte, 2*len(stack))
+			}
+
+			if i := bytes.Index(stack, []byte("\nos/exec.Command(")); i >= 0 {
+				stack = stack[i+1:]
+			}
+			cmd.createdByStack = stack
+		}
+
+		runtime.SetFinalizer(cmd, func(c *Cmd) {
+			if c.Process != nil && c.ProcessState == nil {
+				debugHint := ""
+				if c.createdByStack == nil {
+					debugHint = " (set GODEBUG=execwait=2 to capture stacks for debugging)"
+				} else {
+					os.Stderr.WriteString("GODEBUG=execwait=2 detected a leaked exec.Cmd created by:\n")
+					os.Stderr.Write(c.createdByStack)
+					os.Stderr.WriteString("\n")
+					debugHint = ""
+				}
+				panic("exec: Cmd started a Process but leaked without a call to Wait" + debugHint)
+			}
+		})
+	}
+	*/
+
+	if filepath.Base(name) == name {
+		lp, err := LookPath(name)
+		if lp != "" {
+			// Update cmd.Path even if err is non-nil.
+			// If err is ErrDot (especially on Windows), lp may include a resolved
+			// extension (like .exe or .bat) that should be preserved.
+			cmd.Path = lp
+		}
+		if err != nil {
+			cmd.Err = err
+		}
+	}
+	return cmd
+}
+
+// CommandContext is like Command but includes a context.
+//
+// The provided context is used to interrupt the process
+// (by calling cmd.Cancel or os.Process.Kill)
+// if the context becomes done before the command completes on its own.
+//
+// CommandContext sets the command's Cancel function to invoke the Kill method
+// on its Process, and leaves its WaitDelay unset. The caller may change the
+// cancellation behavior by modifying those fields before starting the command.
+func CommandContext(ctx context.Context, name string, arg ...string) *Cmd {
+	if ctx == nil {
+		panic("nil Context")
+	}
+	cmd := Command(name, arg...)
+	cmd.ctx = ctx
+	cmd.Cancel = func() error {
+		return cmd.Process.Kill()
+	}
+	return cmd
+}
+
+// String returns a human-readable description of c.
+// It is intended only for debugging.
+// In particular, it is not suitable for use as input to a shell.
+// The output of String may vary across Go releases.
+func (c *Cmd) String() string {
+	if c.Err != nil || c.lookPathErr != nil {
+		// failed to resolve path; report the original requested path (plus args)
+		return strings.Join(c.Args, " ")
+	}
+	// report the exact executable path (plus args)
+	b := new(strings.Builder)
+	b.WriteString(c.Path)
+	for _, a := range c.Args[1:] {
+		b.WriteByte(' ')
+		b.WriteString(a)
+	}
+	return b.String()
+}
+
+// interfaceEqual protects against panics from doing equality tests on
+// two interfaces with non-comparable underlying types.
+func interfaceEqual(a, b any) bool {
+	defer func() {
+		recover()
+	}()
+	return a == b
+}
+
+func (c *Cmd) argv() []string {
+	if len(c.Args) > 0 {
+		return c.Args
+	}
+	return []string{c.Path}
+}
+
+func (c *Cmd) childStdin() (*os.File, error) {
+	/* TODO(xsw):
+	if c.Stdin == nil {
+		f, err := os.Open(os.DevNull)
+		if err != nil {
+			return nil, err
+		}
+		c.childIOFiles = append(c.childIOFiles, f)
+		return f, nil
+	}
+
+	if f, ok := c.Stdin.(*os.File); ok {
+		return f, nil
+	}
+
+	pr, pw, err := os.Pipe()
+	if err != nil {
+		return nil, err
+	}
+
+	c.childIOFiles = append(c.childIOFiles, pr)
+	c.parentIOPipes = append(c.parentIOPipes, pw)
+	c.goroutine = append(c.goroutine, func() error {
+		_, err := io.Copy(pw, c.Stdin)
+		if skipStdinCopyError(err) {
+			err = nil
+		}
+		if err1 := pw.Close(); err == nil {
+			err = err1
+		}
+		return err
+	})
+	return pr, nil
+	*/
+	panic("todo: exec.Cmd.childStdin")
+}
+
+func (c *Cmd) childStdout() (*os.File, error) {
+	return c.writerDescriptor(c.Stdout)
+}
+
+func (c *Cmd) childStderr(childStdout *os.File) (*os.File, error) {
+	if c.Stderr != nil && interfaceEqual(c.Stderr, c.Stdout) {
+		return childStdout, nil
+	}
+	return c.writerDescriptor(c.Stderr)
+}
+
+// writerDescriptor returns an os.File to which the child process
+// can write to send data to w.
+//
+// If w is nil, writerDescriptor returns a File that writes to os.DevNull.
+func (c *Cmd) writerDescriptor(w io.Writer) (*os.File, error) {
+	if w == nil {
+		f, err := os.OpenFile(os.DevNull, os.O_WRONLY, 0)
+		if err != nil {
+			return nil, err
+		}
+		c.childIOFiles = append(c.childIOFiles, f)
+		return f, nil
+	}
+
+	if f, ok := w.(*os.File); ok {
+		return f, nil
+	}
+
+	pr, pw, err := os.Pipe()
+	if err != nil {
+		return nil, err
+	}
+
+	c.childIOFiles = append(c.childIOFiles, pw)
+	c.parentIOPipes = append(c.parentIOPipes, pr)
+	c.goroutine = append(c.goroutine, func() error {
+		_, err := io.Copy(w, pr)
+		pr.Close() // in case io.Copy stopped due to write error
+		return err
+	})
+	return pw, nil
+}
+
+func closeDescriptors(closers []io.Closer) {
+	for _, fd := range closers {
+		fd.Close()
+	}
+}
+
+// Run starts the specified command and waits for it to complete.
+//
+// The returned error is nil if the command runs, has no problems
+// copying stdin, stdout, and stderr, and exits with a zero exit
+// status.
+//
+// If the command starts but does not complete successfully, the error is of
+// type *ExitError. Other error types may be returned for other situations.
+//
+// If the calling goroutine has locked the operating system thread
+// with runtime.LockOSThread and modified any inheritable OS-level
+// thread state (for example, Linux or Plan 9 name spaces), the new
+// process will inherit the caller's thread state.
+func (c *Cmd) Run() error {
+	if err := c.Start(); err != nil {
+		return err
+	}
+	return c.Wait()
+}
+
+// lookExtensions finds windows executable by its dir and path.
+// It uses LookPath to try appropriate extensions.
+// lookExtensions does not search PATH, instead it converts `prog` into `.\prog`.
+func lookExtensions(path, dir string) (string, error) {
+	if filepath.Base(path) == path {
+		path = "." + string(filepath.Separator) + path
+	}
+	if dir == "" {
+		return LookPath(path)
+	}
+	if filepath.VolumeName(path) != "" {
+		return LookPath(path)
+	}
+	if len(path) > 1 && os.IsPathSeparator(path[0]) {
+		return LookPath(path)
+	}
+	dirandpath := filepath.Join(dir, path)
+	// We assume that LookPath will only add file extension.
+	lp, err := LookPath(dirandpath)
+	if err != nil {
+		return "", err
+	}
+	ext := strings.TrimPrefix(lp, dirandpath)
+	return path + ext, nil
+}
+
+// Start starts the specified command but does not wait for it to complete.
+//
+// If Start returns successfully, the c.Process field will be set.
+//
+// After a successful call to Start the Wait method must be called in
+// order to release associated system resources.
+func (c *Cmd) Start() error {
+	// Check for doubled Start calls before we defer failure cleanup. If the prior
+	// call to Start succeeded, we don't want to spuriously close its pipes.
+	if c.Process != nil {
+		return errors.New("exec: already started")
+	}
+
+	started := false
+	defer func() {
+		closeDescriptors(c.childIOFiles)
+		c.childIOFiles = nil
+
+		if !started {
+			closeDescriptors(c.parentIOPipes)
+			c.parentIOPipes = nil
+		}
+	}()
+
+	if c.Path == "" && c.Err == nil && c.lookPathErr == nil {
+		c.Err = errors.New("exec: no command")
+	}
+	if c.Err != nil || c.lookPathErr != nil {
+		if c.lookPathErr != nil {
+			return c.lookPathErr
+		}
+		return c.Err
+	}
+	if runtime.GOOS == "windows" {
+		lp, err := lookExtensions(c.Path, c.Dir)
+		if err != nil {
+			return err
+		}
+		c.Path = lp
+	}
+	if c.Cancel != nil && c.ctx == nil {
+		return errors.New("exec: command with a non-nil Cancel was not created with CommandContext")
+	}
+	if c.ctx != nil {
+		select {
+		case <-c.ctx.Done():
+			return c.ctx.Err()
+		default:
+		}
+	}
+
+	childFiles := make([]*os.File, 0, 3+len(c.ExtraFiles))
+	stdin, err := c.childStdin()
+	if err != nil {
+		return err
+	}
+	childFiles = append(childFiles, stdin)
+	stdout, err := c.childStdout()
+	if err != nil {
+		return err
+	}
+	childFiles = append(childFiles, stdout)
+	stderr, err := c.childStderr(stdout)
+	if err != nil {
+		return err
+	}
+	childFiles = append(childFiles, stderr)
+	childFiles = append(childFiles, c.ExtraFiles...)
+
+	env, err := c.environ()
+	if err != nil {
+		return err
+	}
+
+	c.Process, err = os.StartProcess(c.Path, c.argv(), &os.ProcAttr{
+		Dir:   c.Dir,
+		Files: childFiles,
+		Env:   env,
+		Sys:   c.SysProcAttr,
+	})
+	if err != nil {
+		return err
+	}
+	started = true
+
+	// Don't allocate the goroutineErr channel unless there are goroutines to start.
+	if len(c.goroutine) > 0 {
+		goroutineErr := make(chan error, 1)
+		c.goroutineErr = goroutineErr
+
+		type goroutineStatus struct {
+			running  int
+			firstErr error
+		}
+		statusc := make(chan goroutineStatus, 1)
+		statusc <- goroutineStatus{running: len(c.goroutine)}
+		for _, fn := range c.goroutine {
+			go func(fn func() error) {
+				err := fn()
+
+				status := <-statusc
+				if status.firstErr == nil {
+					status.firstErr = err
+				}
+				status.running--
+				if status.running == 0 {
+					goroutineErr <- status.firstErr
+				} else {
+					statusc <- status
+				}
+			}(fn)
+		}
+		c.goroutine = nil // Allow the goroutines' closures to be GC'd when they complete.
+	}
+
+	// If we have anything to do when the command's Context expires,
+	// start a goroutine to watch for cancellation.
+	//
+	// (Even if the command was created by CommandContext, a helper library may
+	// have explicitly set its Cancel field back to nil, indicating that it should
+	// be allowed to continue running after cancellation after all.)
+	if (c.Cancel != nil || c.WaitDelay != 0) && c.ctx != nil && c.ctx.Done() != nil {
+		resultc := make(chan ctxResult)
+		c.ctxResult = resultc
+		go c.watchCtx(resultc)
+	}
+
+	return nil
+}
+
+// watchCtx watches c.ctx until it is able to send a result to resultc.
+//
+// If c.ctx is done before a result can be sent, watchCtx calls c.Cancel,
+// and/or kills cmd.Process it after c.WaitDelay has elapsed.
+//
+// watchCtx manipulates c.goroutineErr, so its result must be received before
+// c.awaitGoroutines is called.
+func (c *Cmd) watchCtx(resultc chan<- ctxResult) {
+	select {
+	case resultc <- ctxResult{}:
+		return
+	case <-c.ctx.Done():
+	}
+
+	var err error
+	if c.Cancel != nil {
+		if interruptErr := c.Cancel(); interruptErr == nil {
+			// We appear to have successfully interrupted the command, so any
+			// program behavior from this point may be due to ctx even if the
+			// command exits with code 0.
+			err = c.ctx.Err()
+		} else if errors.Is(interruptErr, os.ErrProcessDone) {
+			// The process already finished: we just didn't notice it yet.
+			// (Perhaps c.Wait hadn't been called, or perhaps it happened to race with
+			// c.ctx being cancelled.) Don't inject a needless error.
+		} else {
+			err = wrappedError{
+				prefix: "exec: canceling Cmd",
+				err:    interruptErr,
+			}
+		}
+	}
+	if c.WaitDelay == 0 {
+		resultc <- ctxResult{err: err}
+		return
+	}
+
+	timer := time.NewTimer(c.WaitDelay)
+	select {
+	case resultc <- ctxResult{err: err, timer: timer}:
+		// c.Process.Wait returned and we've handed the timer off to c.Wait.
+		// It will take care of goroutine shutdown from here.
+		return
+	case <-timer.C:
+	}
+
+	killed := false
+	if killErr := c.Process.Kill(); killErr == nil {
+		// We appear to have killed the process. c.Process.Wait should return a
+		// non-nil error to c.Wait unless the Kill signal races with a successful
+		// exit, and if that does happen we shouldn't report a spurious error,
+		// so don't set err to anything here.
+		killed = true
+	} else if !errors.Is(killErr, os.ErrProcessDone) {
+		err = wrappedError{
+			prefix: "exec: killing Cmd",
+			err:    killErr,
+		}
+	}
+
+	if c.goroutineErr != nil {
+		select {
+		case goroutineErr := <-c.goroutineErr:
+			// Forward goroutineErr only if we don't have reason to believe it was
+			// caused by a call to Cancel or Kill above.
+			if err == nil && !killed {
+				err = goroutineErr
+			}
+		default:
+			// Close the child process's I/O pipes, in case it abandoned some
+			// subprocess that inherited them and is still holding them open
+			// (see https://go.dev/issue/23019).
+			//
+			// We close the goroutine pipes only after we have sent any signals we're
+			// going to send to the process (via Signal or Kill above): if we send
+			// SIGKILL to the process, we would prefer for it to die of SIGKILL, not
+			// SIGPIPE. (However, this may still cause any orphaned subprocesses to
+			// terminate with SIGPIPE.)
+			closeDescriptors(c.parentIOPipes)
+			// Wait for the copying goroutines to finish, but report ErrWaitDelay for
+			// the error: any other error here could result from closing the pipes.
+			_ = <-c.goroutineErr
+			if err == nil {
+				err = ErrWaitDelay
+			}
+		}
+
+		// Since we have already received the only result from c.goroutineErr,
+		// set it to nil to prevent awaitGoroutines from blocking on it.
+		c.goroutineErr = nil
+	}
+
+	resultc <- ctxResult{err: err}
+}
+
+// An ExitError reports an unsuccessful exit by a command.
+type ExitError struct {
+	*os.ProcessState
+
+	// Stderr holds a subset of the standard error output from the
+	// Cmd.Output method if standard error was not otherwise being
+	// collected.
+	//
+	// If the error output is long, Stderr may contain only a prefix
+	// and suffix of the output, with the middle replaced with
+	// text about the number of omitted bytes.
+	//
+	// Stderr is provided for debugging, for inclusion in error messages.
+	// Users with other needs should redirect Cmd.Stderr as needed.
+	Stderr []byte
+}
+
+func (e *ExitError) Error() string {
+	return e.ProcessState.String()
+}
+
+// Wait waits for the command to exit and waits for any copying to
+// stdin or copying from stdout or stderr to complete.
+//
+// The command must have been started by Start.
+//
+// The returned error is nil if the command runs, has no problems
+// copying stdin, stdout, and stderr, and exits with a zero exit
+// status.
+//
+// If the command fails to run or doesn't complete successfully, the
+// error is of type *ExitError. Other error types may be
+// returned for I/O problems.
+//
+// If any of c.Stdin, c.Stdout or c.Stderr are not an *os.File, Wait also waits
+// for the respective I/O loop copying to or from the process to complete.
+//
+// Wait releases any resources associated with the Cmd.
+func (c *Cmd) Wait() error {
+	if c.Process == nil {
+		return errors.New("exec: not started")
+	}
+	if c.ProcessState != nil {
+		return errors.New("exec: Wait was already called")
+	}
+
+	state, err := c.Process.Wait()
+	if err == nil && !state.Success() {
+		err = &ExitError{ProcessState: state}
+	}
+	c.ProcessState = state
+
+	var timer *time.Timer
+	if c.ctxResult != nil {
+		watch := <-c.ctxResult
+		timer = watch.timer
+		// If c.Process.Wait returned an error, prefer that.
+		// Otherwise, report any error from the watchCtx goroutine,
+		// such as a Context cancellation or a WaitDelay overrun.
+		if err == nil && watch.err != nil {
+			err = watch.err
+		}
+	}
+
+	if goroutineErr := c.awaitGoroutines(timer); err == nil {
+		// Report an error from the copying goroutines only if the program otherwise
+		// exited normally on its own. Otherwise, the copying error may be due to the
+		// abnormal termination.
+		err = goroutineErr
+	}
+	closeDescriptors(c.parentIOPipes)
+	c.parentIOPipes = nil
+
+	return err
+}
+
+// awaitGoroutines waits for the results of the goroutines copying data to or
+// from the command's I/O pipes.
+//
+// If c.WaitDelay elapses before the goroutines complete, awaitGoroutines
+// forcibly closes their pipes and returns ErrWaitDelay.
+//
+// If timer is non-nil, it must send to timer.C at the end of c.WaitDelay.
+func (c *Cmd) awaitGoroutines(timer *time.Timer) error {
+	defer func() {
+		if timer != nil {
+			timer.Stop()
+		}
+		c.goroutineErr = nil
+	}()
+
+	if c.goroutineErr == nil {
+		return nil // No running goroutines to await.
+	}
+
+	if timer == nil {
+		if c.WaitDelay == 0 {
+			return <-c.goroutineErr
+		}
+
+		select {
+		case err := <-c.goroutineErr:
+			// Avoid the overhead of starting a timer.
+			return err
+		default:
+		}
+
+		// No existing timer was started: either there is no Context associated with
+		// the command, or c.Process.Wait completed before the Context was done.
+		timer = time.NewTimer(c.WaitDelay)
+	}
+
+	select {
+	case <-timer.C:
+		closeDescriptors(c.parentIOPipes)
+		// Wait for the copying goroutines to finish, but ignore any error
+		// (since it was probably caused by closing the pipes).
+		_ = <-c.goroutineErr
+		return ErrWaitDelay
+
+	case err := <-c.goroutineErr:
+		return err
+	}
+}
+
+// Output runs the command and returns its standard output.
+// Any returned error will usually be of type *ExitError.
+// If c.Stderr was nil, Output populates ExitError.Stderr.
+func (c *Cmd) Output() ([]byte, error) {
+	if c.Stdout != nil {
+		return nil, errors.New("exec: Stdout already set")
+	}
+	var stdout bytes.Buffer
+	c.Stdout = &stdout
+
+	captureErr := c.Stderr == nil
+	if captureErr {
+		c.Stderr = &prefixSuffixSaver{N: 32 << 10}
+	}
+
+	err := c.Run()
+	if err != nil && captureErr {
+		if ee, ok := err.(*ExitError); ok {
+			ee.Stderr = c.Stderr.(*prefixSuffixSaver).Bytes()
+		}
+	}
+	return stdout.Bytes(), err
+}
+
+// CombinedOutput runs the command and returns its combined standard
+// output and standard error.
+func (c *Cmd) CombinedOutput() ([]byte, error) {
+	if c.Stdout != nil {
+		return nil, errors.New("exec: Stdout already set")
+	}
+	if c.Stderr != nil {
+		return nil, errors.New("exec: Stderr already set")
+	}
+	var b bytes.Buffer
+	c.Stdout = &b
+	c.Stderr = &b
+	err := c.Run()
+	return b.Bytes(), err
+}
+
+// StdinPipe returns a pipe that will be connected to the command's
+// standard input when the command starts.
+// The pipe will be closed automatically after Wait sees the command exit.
+// A caller need only call Close to force the pipe to close sooner.
+// For example, if the command being run will not exit until standard input
+// is closed, the caller must close the pipe.
+func (c *Cmd) StdinPipe() (io.WriteCloser, error) {
+	if c.Stdin != nil {
+		return nil, errors.New("exec: Stdin already set")
+	}
+	if c.Process != nil {
+		return nil, errors.New("exec: StdinPipe after process started")
+	}
+	pr, pw, err := os.Pipe()
+	if err != nil {
+		return nil, err
+	}
+	c.Stdin = pr
+	c.childIOFiles = append(c.childIOFiles, pr)
+	c.parentIOPipes = append(c.parentIOPipes, pw)
+	return pw, nil
+}
+
+// StdoutPipe returns a pipe that will be connected to the command's
+// standard output when the command starts.
+//
+// Wait will close the pipe after seeing the command exit, so most callers
+// need not close the pipe themselves. It is thus incorrect to call Wait
+// before all reads from the pipe have completed.
+// For the same reason, it is incorrect to call Run when using StdoutPipe.
+// See the example for idiomatic usage.
+func (c *Cmd) StdoutPipe() (io.ReadCloser, error) {
+	if c.Stdout != nil {
+		return nil, errors.New("exec: Stdout already set")
+	}
+	if c.Process != nil {
+		return nil, errors.New("exec: StdoutPipe after process started")
+	}
+	pr, pw, err := os.Pipe()
+	if err != nil {
+		return nil, err
+	}
+	c.Stdout = pw
+	c.childIOFiles = append(c.childIOFiles, pw)
+	c.parentIOPipes = append(c.parentIOPipes, pr)
+	return pr, nil
+}
+
+// StderrPipe returns a pipe that will be connected to the command's
+// standard error when the command starts.
+//
+// Wait will close the pipe after seeing the command exit, so most callers
+// need not close the pipe themselves. It is thus incorrect to call Wait
+// before all reads from the pipe have completed.
+// For the same reason, it is incorrect to use Run when using StderrPipe.
+// See the StdoutPipe example for idiomatic usage.
+func (c *Cmd) StderrPipe() (io.ReadCloser, error) {
+	if c.Stderr != nil {
+		return nil, errors.New("exec: Stderr already set")
+	}
+	if c.Process != nil {
+		return nil, errors.New("exec: StderrPipe after process started")
+	}
+	pr, pw, err := os.Pipe()
+	if err != nil {
+		return nil, err
+	}
+	c.Stderr = pw
+	c.childIOFiles = append(c.childIOFiles, pw)
+	c.parentIOPipes = append(c.parentIOPipes, pr)
+	return pr, nil
+}
+
+// prefixSuffixSaver is an io.Writer which retains the first N bytes
+// and the last N bytes written to it. The Bytes() methods reconstructs
+// it with a pretty error message.
+type prefixSuffixSaver struct {
+	N         int // max size of prefix or suffix
+	prefix    []byte
+	suffix    []byte // ring buffer once len(suffix) == N
+	suffixOff int    // offset to write into suffix
+	skipped   int64
+
+	// TODO(bradfitz): we could keep one large []byte and use part of it for
+	// the prefix, reserve space for the '... Omitting N bytes ...' message,
+	// then the ring buffer suffix, and just rearrange the ring buffer
+	// suffix when Bytes() is called, but it doesn't seem worth it for
+	// now just for error messages. It's only ~64KB anyway.
+}
+
+func (w *prefixSuffixSaver) Write(p []byte) (n int, err error) {
+	lenp := len(p)
+	p = w.fill(&w.prefix, p)
+
+	// Only keep the last w.N bytes of suffix data.
+	if overage := len(p) - w.N; overage > 0 {
+		p = p[overage:]
+		w.skipped += int64(overage)
+	}
+	p = w.fill(&w.suffix, p)
+
+	// w.suffix is full now if p is non-empty. Overwrite it in a circle.
+	for len(p) > 0 { // 0, 1, or 2 iterations.
+		n := copy(w.suffix[w.suffixOff:], p)
+		p = p[n:]
+		w.skipped += int64(n)
+		w.suffixOff += n
+		if w.suffixOff == w.N {
+			w.suffixOff = 0
+		}
+	}
+	return lenp, nil
+}
+
+// fill appends up to len(p) bytes of p to *dst, such that *dst does not
+// grow larger than w.N. It returns the un-appended suffix of p.
+func (w *prefixSuffixSaver) fill(dst *[]byte, p []byte) (pRemain []byte) {
+	if remain := w.N - len(*dst); remain > 0 {
+		add := minInt(len(p), remain)
+		*dst = append(*dst, p[:add]...)
+		p = p[add:]
+	}
+	return p
+}
+
+func (w *prefixSuffixSaver) Bytes() []byte {
+	if w.suffix == nil {
+		return w.prefix
+	}
+	if w.skipped == 0 {
+		return append(w.prefix, w.suffix...)
+	}
+	var buf bytes.Buffer
+	buf.Grow(len(w.prefix) + len(w.suffix) + 50)
+	buf.Write(w.prefix)
+	buf.WriteString("\n... omitting ")
+	buf.WriteString(strconv.FormatInt(w.skipped, 10))
+	buf.WriteString(" bytes ...\n")
+	buf.Write(w.suffix[w.suffixOff:])
+	buf.Write(w.suffix[:w.suffixOff])
+	return buf.Bytes()
+}
+
+func minInt(a, b int) int {
+	if a < b {
+		return a
+	}
+	return b
+}
+
+// environ returns a best-effort copy of the environment in which the command
+// 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
+	if env == nil {
+		env, err = execenv.Default(c.SysProcAttr)
+		if err != nil {
+			env = os.Environ()
+			// Note that the non-nil err is preserved despite env being overridden.
+		}
+
+		if c.Dir != "" {
+			switch runtime.GOOS {
+			case "windows", "plan9":
+				// Windows and Plan 9 do not use the PWD variable, so we don't need to
+				// keep it accurate.
+			default:
+				// On POSIX platforms, PWD represents “an absolute pathname of the
+				// current working directory.” Since we are changing the working
+				// directory for the command, we should also update PWD to reflect that.
+				//
+				// Unfortunately, we didn't always do that, so (as proposed in
+				// https://go.dev/issue/50599) to avoid unintended collateral damage we
+				// only implicitly update PWD when Env is nil. That way, we're much
+				// less likely to override an intentional change to the variable.
+				if pwd, absErr := filepath.Abs(c.Dir); absErr == nil {
+					env = append(env, "PWD="+pwd)
+				} else if err == nil {
+					err = absErr
+				}
+			}
+		}
+	}
+
+	env, dedupErr := dedupEnv(env)
+	if err == nil {
+		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
+// as it is currently configured.
+func (c *Cmd) Environ() []string {
+	//  Intentionally ignore errors: environ returns a best-effort environment no matter what.
+	env, _ := c.environ()
+	return env
+}
+
+// dedupEnv returns a copy of env with any duplicates removed, in favor of
+// later values.
+// Items not of the normal environment "key=value" form are preserved unchanged.
+// Except on Plan 9, items containing NUL characters are removed, and
+// an error is returned along with the remaining values.
+func dedupEnv(env []string) ([]string, error) {
+	return dedupEnvCase(runtime.GOOS == "windows", runtime.GOOS == "plan9", env)
+}
+
+// dedupEnvCase is dedupEnv with a case option for testing.
+// If caseInsensitive is true, the case of keys is ignored.
+// If nulOK is false, items containing NUL characters are allowed.
+func dedupEnvCase(caseInsensitive, nulOK bool, env []string) ([]string, error) {
+	// Construct the output in reverse order, to preserve the
+	// last occurrence of each key.
+	var err error
+	out := make([]string, 0, len(env))
+	saw := make(map[string]bool, len(env))
+	for n := len(env); n > 0; n-- {
+		kv := env[n-1]
+
+		// Reject NUL in environment variables to prevent security issues (#56284);
+		// except on Plan 9, which uses NUL as os.PathListSeparator (#56544).
+		if !nulOK && strings.IndexByte(kv, 0) != -1 {
+			err = errors.New("exec: environment variable contains NUL")
+			continue
+		}
+
+		i := strings.Index(kv, "=")
+		if i == 0 {
+			// We observe in practice keys with a single leading "=" on Windows.
+			// TODO(#49886): Should we consume only the first leading "=" as part
+			// of the key, or parse through arbitrarily many of them until a non-"="?
+			i = strings.Index(kv[1:], "=") + 1
+		}
+		if i < 0 {
+			if kv != "" {
+				// The entry is not of the form "key=value" (as it is required to be).
+				// Leave it as-is for now.
+				// TODO(#52436): should we strip or reject these bogus entries?
+				out = append(out, kv)
+			}
+			continue
+		}
+		k := kv[:i]
+		if caseInsensitive {
+			k = strings.ToLower(k)
+		}
+		if saw[k] {
+			continue
+		}
+
+		saw[k] = true
+		out = append(out, kv)
+	}
+
+	// Now reverse the slice to restore the original order.
+	for i := 0; i < len(out)/2; i++ {
+		j := len(out) - i - 1
+		out[i], out[j] = out[j], out[i]
+	}
+
+	return out, err
+}
+
+// addCriticalEnv adds any critical environment variables that are required
+// (or at least almost always required) on the operating system.
+// Currently this is only used for Windows.
+func addCriticalEnv(env []string) []string {
+	if runtime.GOOS != "windows" {
+		return env
+	}
+	for _, kv := range env {
+		k, _, ok := strings.Cut(kv, "=")
+		if !ok {
+			continue
+		}
+		if strings.EqualFold(k, "SYSTEMROOT") {
+			// We already have it.
+			return env
+		}
+	}
+	return append(env, "SYSTEMROOT="+os.Getenv("SYSTEMROOT"))
+}
+
+// ErrDot indicates that a path lookup resolved to an executable
+// in the current directory due to ‘.’ being in the path, either
+// implicitly or explicitly. See the package documentation for details.
+//
+// Note that functions in this package do not return ErrDot directly.
+// Code should use errors.Is(err, ErrDot), not err == ErrDot,
+// to test whether a returned error err is due to this condition.
+var ErrDot = errors.New("cannot run executable found relative to current directory")
diff --git a/internal/lib/os/exec/lp_unix.go b/internal/lib/os/exec/lp_unix.go
index 7d6bbc02..757189d2 100644
--- a/internal/lib/os/exec/lp_unix.go
+++ b/internal/lib/os/exec/lp_unix.go
@@ -8,13 +8,17 @@ package exec
 
 import (
 	"errors"
+	"io/fs"
+	"os"
+	"path/filepath"
+	"strings"
+	"syscall"
 )
 
 // ErrNotFound is the error resulting if a path search failed to find an executable file.
 var ErrNotFound = errors.New("executable file not found in $PATH")
 
 func findExecutable(file string) error {
-	/* TODO(xsw):
 	d, err := os.Stat(file)
 	if err != nil {
 		return err
@@ -23,7 +27,7 @@ func findExecutable(file string) error {
 	if m.IsDir() {
 		return syscall.EISDIR
 	}
-	err = unix.Eaccess(file, unix.X_OK)
+	err = unixEaccess(file, unix_X_OK)
 	// ENOSYS means Eaccess is not available or not implemented.
 	// EPERM can be returned by Linux containers employing seccomp.
 	// In both cases, fall back to checking the permission bits.
@@ -34,8 +38,6 @@ func findExecutable(file string) error {
 		return nil
 	}
 	return fs.ErrPermission
-	*/
-	panic("todo: exec.findExecutable")
 }
 
 // LookPath searches for an executable named file in the
@@ -47,7 +49,6 @@ func findExecutable(file string) error {
 // As of Go 1.19, LookPath will instead return that path along with an error satisfying
 // errors.Is(err, ErrDot). See the package documentation for more details.
 func LookPath(file string) (string, error) {
-	/* TODO(xsw):
 	// NOTE(rsc): I wish we could use the Plan 9 behavior here
 	// (only bypass the path if file begins with / or ./ or ../)
 	// but that would not match all the Unix shells.
@@ -68,15 +69,16 @@ func LookPath(file string) (string, error) {
 		path := filepath.Join(dir, file)
 		if err := findExecutable(path); err == nil {
 			if !filepath.IsAbs(path) {
+				/* TODO(xsw):
 				if execerrdot.Value() != "0" {
 					return path, &Error{file, ErrDot}
 				}
 				execerrdot.IncNonDefault()
+				*/
+				panic("todo: exec.LookPath: !filepath.IsAbs(path)")
 			}
 			return path, nil
 		}
 	}
 	return "", &Error{file, ErrNotFound}
-	*/
-	panic("todo: exec.LookPath")
 }
diff --git a/internal/lib/os/exec/unix_constants.go b/internal/lib/os/exec/unix_constants.go
new file mode 100644
index 00000000..8bbbbac8
--- /dev/null
+++ b/internal/lib/os/exec/unix_constants.go
@@ -0,0 +1,13 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build unix
+
+package exec
+
+const (
+	unix_R_OK = 0x4
+	unix_W_OK = 0x2
+	unix_X_OK = 0x1
+)
diff --git a/internal/lib/os/exec/unix_eaccess_linux.go b/internal/lib/os/exec/unix_eaccess_linux.go
new file mode 100644
index 00000000..68d250b9
--- /dev/null
+++ b/internal/lib/os/exec/unix_eaccess_linux.go
@@ -0,0 +1,11 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package exec
+
+import "syscall"
+
+func unixEaccess(path string, mode uint32) error {
+	return syscall.Faccessat(AT_FDCWD, path, mode, AT_EACCESS)
+}
diff --git a/internal/lib/os/exec/unix_eaccess_other.go b/internal/lib/os/exec/unix_eaccess_other.go
new file mode 100644
index 00000000..8b99269c
--- /dev/null
+++ b/internal/lib/os/exec/unix_eaccess_other.go
@@ -0,0 +1,13 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build unix && !linux
+
+package exec
+
+import "syscall"
+
+func unixEaccess(path string, mode uint32) error {
+	return syscall.ENOSYS
+}
diff --git a/internal/lib/syscall/syscall.go b/internal/lib/syscall/syscall.go
index a28d8820..045dc87b 100644
--- a/internal/lib/syscall/syscall.go
+++ b/internal/lib/syscall/syscall.go
@@ -24,6 +24,34 @@ import (
 	"github.com/goplus/llgo/c/os"
 )
 
+// Unix returns the time stored in ts as seconds plus nanoseconds.
+func (ts *Timespec) Unix() (sec int64, nsec int64) {
+	return int64(ts.Sec), int64(ts.Nsec)
+}
+
+// Unix returns the time stored in tv as seconds plus nanoseconds.
+func (tv *Timeval) Unix() (sec int64, nsec int64) {
+	return int64(tv.Sec), int64(tv.Usec) * 1000
+}
+
+// Nano returns the time stored in ts as nanoseconds.
+func (ts *Timespec) Nano() int64 {
+	return int64(ts.Sec)*1e9 + int64(ts.Nsec)
+}
+
+// Nano returns the time stored in tv as nanoseconds.
+func (tv *Timeval) Nano() int64 {
+	return int64(tv.Sec)*1e9 + int64(tv.Usec)*1000
+}
+
+func Getpagesize() int {
+	panic("todo: syscall.Getpagesize")
+}
+
+func Exit(code int) {
+	os.Exit(c.Int(code))
+}
+
 func Getcwd(buf []byte) (n int, err error) {
 	ptr := unsafe.Pointer(unsafe.SliceData(buf))
 	ret := os.Getcwd(ptr, uintptr(len(buf)))