diff --git a/c/syscall/unix/at_sysnum_darwin.go b/c/syscall/unix/at_sysnum_darwin.go
new file mode 100644
index 00000000..208ff34d
--- /dev/null
+++ b/c/syscall/unix/at_sysnum_darwin.go
@@ -0,0 +1,10 @@
+// Copyright 2018 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 unix
+
+const AT_REMOVEDIR = 0x80
+const AT_SYMLINK_NOFOLLOW = 0x0020
+
+const UTIME_OMIT = -0x2
diff --git a/c/syscall/unix/at_sysnum_dragonfly.go b/c/syscall/unix/at_sysnum_dragonfly.go
new file mode 100644
index 00000000..b7ed3f73
--- /dev/null
+++ b/c/syscall/unix/at_sysnum_dragonfly.go
@@ -0,0 +1,16 @@
+// Copyright 2018 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 unix
+
+import "syscall"
+
+const unlinkatTrap uintptr = syscall.SYS_UNLINKAT
+const openatTrap uintptr = syscall.SYS_OPENAT
+const fstatatTrap uintptr = syscall.SYS_FSTATAT
+
+const AT_REMOVEDIR = 0x2
+const AT_SYMLINK_NOFOLLOW = 0x1
+
+const UTIME_OMIT = -0x1
diff --git a/c/syscall/unix/at_sysnum_freebsd.go b/c/syscall/unix/at_sysnum_freebsd.go
new file mode 100644
index 00000000..9cd5da6c
--- /dev/null
+++ b/c/syscall/unix/at_sysnum_freebsd.go
@@ -0,0 +1,18 @@
+// Copyright 2018 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 unix
+
+import "syscall"
+
+const (
+	AT_REMOVEDIR        = 0x800
+	AT_SYMLINK_NOFOLLOW = 0x200
+
+	UTIME_OMIT = -0x2
+
+	unlinkatTrap       uintptr = syscall.SYS_UNLINKAT
+	openatTrap         uintptr = syscall.SYS_OPENAT
+	posixFallocateTrap uintptr = syscall.SYS_POSIX_FALLOCATE
+)
diff --git a/c/syscall/unix/at_sysnum_fstatat64_linux.go b/c/syscall/unix/at_sysnum_fstatat64_linux.go
new file mode 100644
index 00000000..445b0c38
--- /dev/null
+++ b/c/syscall/unix/at_sysnum_fstatat64_linux.go
@@ -0,0 +1,11 @@
+// Copyright 2018 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 arm || mips || mipsle || 386
+
+package unix
+
+import "syscall"
+
+const fstatatTrap uintptr = syscall.SYS_FSTATAT64
diff --git a/c/syscall/unix/at_sysnum_fstatat_linux.go b/c/syscall/unix/at_sysnum_fstatat_linux.go
new file mode 100644
index 00000000..73a3da5b
--- /dev/null
+++ b/c/syscall/unix/at_sysnum_fstatat_linux.go
@@ -0,0 +1,11 @@
+// Copyright 2018 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 arm64 || riscv64
+
+package unix
+
+import "syscall"
+
+const fstatatTrap uintptr = syscall.SYS_FSTATAT
diff --git a/c/syscall/unix/at_sysnum_linux.go b/c/syscall/unix/at_sysnum_linux.go
new file mode 100644
index 00000000..7c3b15c3
--- /dev/null
+++ b/c/syscall/unix/at_sysnum_linux.go
@@ -0,0 +1,19 @@
+// Copyright 2018 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 unix
+
+import "syscall"
+
+const unlinkatTrap uintptr = syscall.SYS_UNLINKAT
+const openatTrap uintptr = syscall.SYS_OPENAT
+
+const (
+	AT_EACCESS          = 0x200
+	AT_FDCWD            = -0x64
+	AT_REMOVEDIR        = 0x200
+	AT_SYMLINK_NOFOLLOW = 0x100
+
+	UTIME_OMIT = 0x3ffffffe
+)
diff --git a/c/syscall/unix/at_sysnum_netbsd.go b/c/syscall/unix/at_sysnum_netbsd.go
new file mode 100644
index 00000000..becc1bdf
--- /dev/null
+++ b/c/syscall/unix/at_sysnum_netbsd.go
@@ -0,0 +1,16 @@
+// Copyright 2018 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 unix
+
+import "syscall"
+
+const unlinkatTrap uintptr = syscall.SYS_UNLINKAT
+const openatTrap uintptr = syscall.SYS_OPENAT
+const fstatatTrap uintptr = syscall.SYS_FSTATAT
+
+const AT_REMOVEDIR = 0x800
+const AT_SYMLINK_NOFOLLOW = 0x200
+
+const UTIME_OMIT = (1 << 30) - 2
diff --git a/c/syscall/unix/at_sysnum_newfstatat_linux.go b/c/syscall/unix/at_sysnum_newfstatat_linux.go
new file mode 100644
index 00000000..76edf675
--- /dev/null
+++ b/c/syscall/unix/at_sysnum_newfstatat_linux.go
@@ -0,0 +1,11 @@
+// Copyright 2018 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 amd64 || mips64 || mips64le || ppc64 || ppc64le || s390x
+
+package unix
+
+import "syscall"
+
+const fstatatTrap uintptr = syscall.SYS_NEWFSTATAT
diff --git a/c/syscall/unix/at_sysnum_openbsd.go b/c/syscall/unix/at_sysnum_openbsd.go
new file mode 100644
index 00000000..fd389477
--- /dev/null
+++ b/c/syscall/unix/at_sysnum_openbsd.go
@@ -0,0 +1,16 @@
+// Copyright 2018 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 unix
+
+import "syscall"
+
+const unlinkatTrap uintptr = syscall.SYS_UNLINKAT
+const openatTrap uintptr = syscall.SYS_OPENAT
+const fstatatTrap uintptr = syscall.SYS_FSTATAT
+
+const AT_REMOVEDIR = 0x08
+const AT_SYMLINK_NOFOLLOW = 0x02
+
+const UTIME_OMIT = -0x1
diff --git a/internal/lib/os/exec/unix_eaccess_linux.go b/internal/lib/os/exec/unix_eaccess_linux.go
index 68d250b9..3d6a1389 100644
--- a/internal/lib/os/exec/unix_eaccess_linux.go
+++ b/internal/lib/os/exec/unix_eaccess_linux.go
@@ -4,8 +4,12 @@
 
 package exec
 
-import "syscall"
+import (
+	"syscall"
+
+	"github.com/goplus/llgo/c/syscall/unix"
+)
 
 func unixEaccess(path string, mode uint32) error {
-	return syscall.Faccessat(AT_FDCWD, path, mode, AT_EACCESS)
+	return syscall.Faccessat(unix.AT_FDCWD, path, mode, unix.AT_EACCESS)
 }
diff --git a/internal/lib/os/file_unix.go b/internal/lib/os/file_unix.go
index 1450ff18..fe390562 100644
--- a/internal/lib/os/file_unix.go
+++ b/internal/lib/os/file_unix.go
@@ -7,7 +7,6 @@
 package os
 
 import (
-	"io/fs"
 	"runtime"
 )
 
@@ -173,7 +172,10 @@ func (d *unixDirent) Info() (FileInfo, error) {
 }
 
 func (d *unixDirent) String() string {
+	/* TODO(xsw):
 	return fs.FormatDirEntry(d)
+	*/
+	panic("todo: os.unixDirent.String")
 }
 
 /* TODO(xsw):
diff --git a/internal/lib/syscall/syscall_linux.go b/internal/lib/syscall/syscall_linux.go
new file mode 100644
index 00000000..a3e05ff2
--- /dev/null
+++ b/internal/lib/syscall/syscall_linux.go
@@ -0,0 +1,16 @@
+// Copyright 2009 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.
+
+// Linux system calls.
+// This file is compiled as ordinary Go code,
+// but it is also input to mksyscall,
+// which parses the //sys lines and generates system call stubs.
+// Note that sometimes we use a lowercase //sys name and
+// wrap it in our own nicer implementation.
+
+package syscall
+
+func Faccessat(dirfd int, path string, mode uint32, flags int) (err error) {
+	panic("todo: syscall.Faccessat")
+}