diff --git a/_cmptest/osexec/exec.go b/_cmptest/osexec/exec.go
index ec983c4b..31eb2ec1 100644
--- a/_cmptest/osexec/exec.go
+++ b/_cmptest/osexec/exec.go
@@ -1,6 +1,7 @@
 package main
 
 import (
+	"fmt"
 	"os"
 	"os/exec"
 	"runtime"
@@ -15,4 +16,7 @@ func main() {
 	cmd.Stdout = os.Stdout
 	cmd.Stderr = os.Stderr
 	cmd.Run()
+
+	output, _ := exec.Command(ls).Output()
+	fmt.Print(string(output))
 }
diff --git a/internal/lib/fmt/print.go b/internal/lib/fmt/print.go
index 88786f0a..450d5a0d 100644
--- a/internal/lib/fmt/print.go
+++ b/internal/lib/fmt/print.go
@@ -1218,19 +1218,16 @@ formatLoop:
 }
 
 func (p *pp) doPrint(a []any) {
-	/*
-		prevString := false
-		for argNum, arg := range a {
-			isString := arg != nil && reflect.TypeOf(arg).Kind() == reflect.String
-			// Add a space between two non-string arguments.
-			if argNum > 0 && !isString && !prevString {
-				p.buf.writeByte(' ')
-			}
-			p.printArg(arg, 'v')
-			prevString = isString
+	prevString := false
+	for argNum, arg := range a {
+		isString := arg != nil && reflect.TypeOf(arg).Kind() == reflect.String
+		// Add a space between two non-string arguments.
+		if argNum > 0 && !isString && !prevString {
+			p.buf.writeByte(' ')
 		}
-	*/
-	panic("todo: fmt.(*pp).doPrint")
+		p.printArg(arg, 'v')
+		prevString = isString
+	}
 }
 
 // doPrintln is like doPrint but always adds a space between arguments
diff --git a/internal/lib/syscall/exec_libc2.go b/internal/lib/syscall/exec_libc2.go
index 02237240..12bcfcbc 100644
--- a/internal/lib/syscall/exec_libc2.go
+++ b/internal/lib/syscall/exec_libc2.go
@@ -7,6 +7,8 @@
 package syscall
 
 import (
+	"unsafe"
+
 	"github.com/goplus/llgo/c"
 	"github.com/goplus/llgo/c/os"
 	"github.com/goplus/llgo/c/syscall"
@@ -322,12 +324,9 @@ func forkAndExecInChild(argv0 *c.Char, argv, envv **c.Char, chroot, dir *c.Char,
 	*/
 
 childerror:
-	/* TODO(xsw):
 	// send error code on pipe
-	rawSyscall(abi.FuncPCABI0(libc_write_trampoline), uintptr(pipe), uintptr(unsafe.Pointer(&err1)), unsafe.Sizeof(err1))
+	os.Write(c.Int(pipe), unsafe.Pointer(&err1), unsafe.Sizeof(err1))
 	for {
-		rawSyscall(abi.FuncPCABI0(libc_exit_trampoline), 253, 0, 0)
+		os.Exit(253)
 	}
-	*/
-	panic("todo: syscall.forkAndExecInChild - childerror")
 }