diff --git a/userspace/etc/test.sh b/userspace/etc/test.sh
new file mode 100755
index 00000000..0f840cc8
--- /dev/null
+++ b/userspace/etc/test.sh
@@ -0,0 +1,4 @@
+#!/bin/sh
+
+/mnt/bin/clang -cc1as -filetype obj -main-file-name test.S -target-cpu x86-64 -mrelocation-model pic -triple x86_64-unknown-yggdrasil -o /test.o /etc/test.S
+/bin/ls -lh /
diff --git a/userspace/lib/ygglibc/src/headers/spawn/mod.rs b/userspace/lib/ygglibc/src/headers/spawn/mod.rs
index 357994e2..06d8fa68 100644
--- a/userspace/lib/ygglibc/src/headers/spawn/mod.rs
+++ b/userspace/lib/ygglibc/src/headers/spawn/mod.rs
@@ -1,10 +1,17 @@
 use core::ffi::{c_char, c_int, c_short, c_void};
 
+use alloc::vec::Vec;
+use yggdrasil_rt::{io::RawFd, process::{SpawnFlags, SpawnOption, SpawnOptions}, sys as syscall};
+
 use super::{
     sched::__ygg_sched_param_t,
     sys_types::{mode_t, pid_t},
 };
-use crate::util::PointerStrExt;
+use crate::{
+    error::{CIntCountResult, CIntZeroResult, ResultExt},
+    headers::errno::Errno,
+    util::{NullTerminatedArrayIter, PointerStrExt},
+};
 
 #[repr(C)]
 pub struct posix_spawnattr_t {}
@@ -21,15 +28,39 @@ pub const POSIX_SPAWN_SETSIGMASK: c_int = 1 << 6;
 
 #[no_mangle]
 unsafe extern "C" fn posix_spawn(
-    _pid: *mut pid_t,
+    pid: *mut pid_t,
     path: *const c_char,
     _file_actions: *const posix_spawn_file_actions_t,
     _attrp: *const posix_spawnattr_t,
-    _argv: *const *mut c_char,
+    argv: *const *mut c_char,
     _envp: *const *mut c_char,
-) -> c_int {
+) -> CIntZeroResult {
     let path = path.ensure_str();
-    todo!("TODO: posix_spawn({path:?})")
+    let argv = NullTerminatedArrayIter::new(argv);
+    let args = argv
+        .map(|arg| arg.cast_const().ensure_str())
+        .collect::<Vec<_>>();
+
+    log::info!("posix_spawn({path:?}, {args:?})");
+
+    let options = SpawnOptions {
+        program: path,
+        arguments: &args,
+        environment: &[],
+        directory: None,
+        optional: &[
+            SpawnOption::CopyFile { source: RawFd::STDIN, child: RawFd::STDIN },
+            SpawnOption::CopyFile { source: RawFd::STDOUT, child: RawFd::STDOUT },
+            SpawnOption::CopyFile { source: RawFd::STDERR, child: RawFd::STDERR },
+        ],
+        flags: SpawnFlags::empty(),
+    };
+    let id = syscall::spawn_process(&options).e_map_err(Errno::from)?;
+    if let Some(pid) = pid.as_mut() {
+        *pid = id.bits() as i32;
+    }
+
+    CIntZeroResult::SUCCESS
 }
 
 #[no_mangle]
diff --git a/userspace/lib/ygglibc/src/headers/unistd/fs.rs b/userspace/lib/ygglibc/src/headers/unistd/fs.rs
index 26f911df..ee4b6304 100644
--- a/userspace/lib/ygglibc/src/headers/unistd/fs.rs
+++ b/userspace/lib/ygglibc/src/headers/unistd/fs.rs
@@ -1,6 +1,14 @@
 use core::ffi::{c_char, c_int, c_long};
 
-use crate::{error::CIntZeroResult, headers::{fcntl::{faccessat, AT_FDCWD}, sys_types::{gid_t, off_t, uid_t}}, util::PointerExt};
+use crate::{
+    error::{CIntZeroResult, TryFromExt},
+    headers::{
+        fcntl::{faccessat, AT_FDCWD},
+        sys_types::{gid_t, off_t, uid_t},
+    },
+    io::{raw::RawFile, FromRawFd},
+    util::PointerExt,
+};
 
 pub const _PC_PATH_MAX: c_int = 0;
 
@@ -40,8 +48,11 @@ unsafe extern "C" fn fpathconf(fd: c_int, name: c_int) -> c_long {
 }
 
 #[no_mangle]
-unsafe extern "C" fn ftruncate(fd: c_int, size: off_t) -> c_int {
-    todo!()
+unsafe extern "C" fn ftruncate(fd: c_int, size: off_t) -> CIntZeroResult {
+    let mut file = RawFile::e_try_from(fd)?;
+    let size: u64 = size.try_into().unwrap();
+    file.truncate(size)?;
+    CIntZeroResult::SUCCESS
 }
 
 #[no_mangle]
diff --git a/userspace/lib/ygglibc/src/headers/unistd/io.rs b/userspace/lib/ygglibc/src/headers/unistd/io.rs
index db0dde34..c0b21757 100644
--- a/userspace/lib/ygglibc/src/headers/unistd/io.rs
+++ b/userspace/lib/ygglibc/src/headers/unistd/io.rs
@@ -45,7 +45,7 @@ unsafe extern "C" fn fsync(fd: c_int) -> CIntZeroResult {
 #[no_mangle]
 unsafe extern "C" fn isatty(fd: c_int) -> c_int {
     log::error!("TODO: isatty()");
-    1
+    0
 }
 
 #[no_mangle]
diff --git a/userspace/lib/ygglibc/src/headers/unistd/util.rs b/userspace/lib/ygglibc/src/headers/unistd/util.rs
index ef9a7ff0..27f3b35f 100644
--- a/userspace/lib/ygglibc/src/headers/unistd/util.rs
+++ b/userspace/lib/ygglibc/src/headers/unistd/util.rs
@@ -46,7 +46,7 @@ unsafe extern "C" fn swab(from: *const c_void, to: *mut c_void, n: isize) {
 #[no_mangle]
 unsafe extern "C" fn sysconf(name: Sysconf) -> c_long {
     match name {
-        Sysconf::_SC_ARG_MAX => 256,
+        Sysconf::_SC_ARG_MAX => 4096,
         Sysconf::_SC_PAGE_SIZE => 0x1000,
         _ => todo!("{name:?}"),
     }
diff --git a/userspace/lib/ygglibc/src/io/raw.rs b/userspace/lib/ygglibc/src/io/raw.rs
index 37036b61..cf49772d 100644
--- a/userspace/lib/ygglibc/src/io/raw.rs
+++ b/userspace/lib/ygglibc/src/io/raw.rs
@@ -29,6 +29,11 @@ impl RawFile {
         EResult::Ok(())
     }
 
+    pub fn truncate(&mut self, size: u64) -> EResult<()> {
+        unsafe { syscall::truncate(self.0, size) }?;
+        EResult::Ok(())
+    }
+
     pub fn duplicate(&self, new: Option<RawFd>) -> EResult<Self> {
         let fd = unsafe { syscall::clone_fd(self.0, new) }?;
         EResult::Ok(Self(fd))
diff --git a/userspace/lib/ygglibc/src/util.rs b/userspace/lib/ygglibc/src/util.rs
index 8073384b..d89e4783 100644
--- a/userspace/lib/ygglibc/src/util.rs
+++ b/userspace/lib/ygglibc/src/util.rs
@@ -12,6 +12,54 @@ use crate::{
     headers::{errno::Errno, fcntl::AT_FDCWD},
 };
 
+pub trait Pointer {
+    type Pointee;
+
+    fn is_null(self) -> bool;
+}
+
+impl<T> Pointer for *const T {
+    type Pointee = T;
+
+    fn is_null(self) -> bool {
+        <*const T>::is_null(self)
+    }
+}
+
+impl<T> Pointer for *mut T {
+    type Pointee = T;
+
+    fn is_null(self) -> bool {
+        <*mut T>::is_null(self)
+    }
+}
+
+pub struct NullTerminatedArrayIter<T: Pointer> {
+    pointer: *const T,
+}
+
+impl<T: Pointer + Copy> NullTerminatedArrayIter<T> {
+    pub fn new(pointer: *const T) -> Self {
+        Self { pointer }
+    }
+}
+
+impl<T: Pointer + Copy> Iterator for NullTerminatedArrayIter<T> {
+    type Item = T;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        if self.pointer.is_null() {
+            return None;
+        }
+        let current = unsafe { *self.pointer };
+        if current.is_null() {
+            return None;
+        }
+        self.pointer = unsafe { self.pointer.add(1) };
+        Some(current)
+    }
+}
+
 pub trait PointerExt {
     unsafe fn ensure(self: *const Self) -> &'static Self;
     unsafe fn ensure_mut(self: *mut Self) -> &'static mut Self;