diff --git a/src/lib_linux/os.py b/src/lib_linux/os.py
new file mode 100644
index 0000000000..1645a2cfcb
--- /dev/null
+++ b/src/lib_linux/os.py
@@ -0,0 +1,256 @@
+import array
+import ustruct as struct
+import errno as errno_
+import stat as stat_
+import ffilib
+import uos
+
+R_OK = const(4)
+W_OK = const(2)
+X_OK = const(1)
+F_OK = const(0)
+
+O_ACCMODE  = 0o0000003
+O_RDONLY   = 0o0000000
+O_WRONLY   = 0o0000001
+O_RDWR     = 0o0000002
+O_CREAT    = 0o0000100
+O_EXCL     = 0o0000200
+O_NOCTTY   = 0o0000400
+O_TRUNC    = 0o0001000
+O_APPEND   = 0o0002000
+O_NONBLOCK = 0o0004000
+
+error = OSError
+name = "posix"
+sep = "/"
+curdir = "."
+pardir = ".."
+environ = {"WARNING": "NOT_IMPLEMENTED"}
+
+
+libc = ffilib.libc()
+
+if libc:
+    chdir_ = libc.func("i", "chdir", "s")
+    mkdir_ = libc.func("i", "mkdir", "si")
+    rename_ = libc.func("i", "rename", "ss")
+    unlink_ = libc.func("i", "unlink", "s")
+    rmdir_ = libc.func("i", "rmdir", "s")
+    getcwd_ = libc.func("s", "getcwd", "si")
+    opendir_ = libc.func("P", "opendir", "s")
+    readdir_ = libc.func("P", "readdir", "P")
+    open_ = libc.func("i", "open", "sii")
+    read_ = libc.func("i", "read", "ipi")
+    write_ = libc.func("i", "write", "iPi")
+    close_ = libc.func("i", "close", "i")
+    dup_ = libc.func("i", "dup", "i")
+    access_ = libc.func("i", "access", "si")
+    fork_ = libc.func("i", "fork", "")
+    pipe_ = libc.func("i", "pipe", "p")
+    _exit_ = libc.func("v", "_exit", "i")
+    getpid_ = libc.func("i", "getpid", "")
+    waitpid_ = libc.func("i", "waitpid", "ipi")
+    system_ = libc.func("i", "system", "s")
+    execvp_ = libc.func("i", "execvp", "PP")
+    kill_ = libc.func("i", "kill", "ii")
+    getenv_ = libc.func("s", "getenv", "P")
+
+
+
+
+def check_error(ret):
+    # Return True is error was EINTR (which usually means that OS call
+    # should be restarted).
+    if ret == -1:
+        e = uos.errno()
+        if e == errno_.EINTR:
+            return True
+        raise OSError(e)
+
+def raise_error():
+    raise OSError(uos.errno())
+
+stat = uos.stat
+
+def getcwd():
+    buf = bytearray(512)
+    return getcwd_(buf, 512)
+
+def mkdir(name, mode=0o777):
+    e = mkdir_(name, mode)
+    check_error(e)
+
+def rename(old, new):
+    e = rename_(old, new)
+    check_error(e)
+
+def unlink(name):
+    e = unlink_(name)
+    check_error(e)
+
+def rmdir(name):
+    e = rmdir_(name)
+    check_error(e)
+
+def makedirs(name, mode=0o777, exist_ok=False):
+    s = ""
+    comps = name.split("/")
+    if comps[-1] == "":
+        comps.pop()
+    for i, c in enumerate(comps):
+        s += c + "/"
+        try:
+            uos.mkdir(s)
+        except OSError as e:
+            if e.args[0] != errno_.EEXIST:
+                raise
+            if i == len(comps) - 1:
+                if exist_ok:
+                    return
+                raise e
+
+if hasattr(uos, "ilistdir"):
+    ilistdir = uos.ilistdir
+else:
+    def ilistdir(path="."):
+        dir = opendir_(path)
+        if not dir:
+            raise_error()
+        res = []
+        dirent_fmt = "LLHB256s"
+        while True:
+            dirent = readdir_(dir)
+            if not dirent:
+                break
+            import uctypes
+            dirent = uctypes.bytes_at(dirent, struct.calcsize(dirent_fmt))
+            dirent = struct.unpack(dirent_fmt, dirent)
+            dirent = (dirent[-1].split(b'\0', 1)[0], dirent[-2], dirent[0])
+            yield dirent
+
+def listdir(path="."):
+    is_str = type(path) is not bytes
+    res = []
+    for dirent in ilistdir(path):
+        fname = dirent[0]
+        if fname not in (b".", b"..", ".", ".."):
+            if is_str:
+                fname = fsdecode(fname)
+            res.append(fname)
+    return res
+
+def walk(top, topdown=True):
+    files = []
+    dirs = []
+    for dirent in ilistdir_ex(top):
+        mode = dirent[3] << 12
+        fname = dirent[4].split(b'\0', 1)[0]
+        if stat_.S_ISDIR(mode):
+            if fname != b"." and fname != b"..":
+                dirs.append(fsdecode(fname))
+        else:
+            files.append(fsdecode(fname))
+    if topdown:
+        yield top, dirs, files
+    for d in dirs:
+        yield from walk(top + "/" + d, topdown)
+    if not topdown:
+        yield top, dirs, files
+
+def open(n, flags, mode=0o777):
+    r = open_(n, flags, mode)
+    check_error(r)
+    return r
+
+def read(fd, n):
+    buf = bytearray(n)
+    r = read_(fd, buf, n)
+    check_error(r)
+    return bytes(buf[:r])
+
+def write(fd, buf):
+    r = write_(fd, buf, len(buf))
+    check_error(r)
+    return r
+
+def close(fd):
+    r = close_(fd)
+    check_error(r)
+    return r
+
+def dup(fd):
+    r = dup_(fd)
+    check_error(r)
+    return r
+
+def access(path, mode):
+    return access_(path, mode) == 0
+
+def chdir(dir):
+    r = chdir_(dir)
+    check_error(r)
+
+def fork():
+    r = fork_()
+    check_error(r)
+    return r
+
+def pipe():
+    a = array.array('i', [0, 0])
+    r = pipe_(a)
+    check_error(r)
+    return a[0], a[1]
+
+def _exit(n):
+    _exit_(n)
+
+def execvp(f, args):
+    import uctypes
+    args_ = array.array("P", [0] * (len(args) + 1))
+    i = 0
+    for a in args:
+        args_[i] = uctypes.addressof(a)
+        i += 1
+    r = execvp_(f, uctypes.addressof(args_))
+    check_error(r)
+
+def getpid():
+    return getpid_()
+
+def waitpid(pid, opts):
+    a = array.array('i', [0])
+    r = waitpid_(pid, a, opts)
+    check_error(r)
+    return (r, a[0])
+
+def kill(pid, sig):
+    r = kill_(pid, sig)
+    check_error(r)
+
+def system(command):
+    r = system_(command)
+    check_error(r)
+    return r
+
+def getenv(var, default=None):
+    var = getenv_(var)
+    if var is None:
+        return default
+    return var
+
+def fsencode(s):
+    if type(s) is bytes:
+        return s
+    return bytes(s, "utf-8")
+
+def fsdecode(s):
+    if type(s) is str:
+        return s
+    return str(s, "utf-8")
+
+
+def urandom(n):
+    import builtins
+    with builtins.open("/dev/urandom", "rb") as f:
+        return f.read(n)