diff --git a/user/src/bin/infloop.rs b/user/src/bin/infloop.rs
new file mode 100644
index 00000000..6e8964d5
--- /dev/null
+++ b/user/src/bin/infloop.rs
@@ -0,0 +1,9 @@
+#![no_std]
+#![no_main]
+
+extern crate user_lib;
+
+#[no_mangle]
+pub fn main(_argc: usize, _argv: &[&str]) -> ! {
+    loop {}
+}
diff --git a/user/src/bin/until_timeout.rs b/user/src/bin/until_timeout.rs
new file mode 100644
index 00000000..2a5c0529
--- /dev/null
+++ b/user/src/bin/until_timeout.rs
@@ -0,0 +1,44 @@
+#![no_std]
+#![no_main]
+
+#[macro_use]
+extern crate user_lib;
+
+use user_lib::{fork, exec, kill, waitpid_nb, waitpid, get_time, SignalFlags};
+
+#[no_mangle]
+pub fn main(argc: usize, argv: &[&str]) -> i32 {
+    assert_eq!(argc, 3, "argc must be 3!");
+    let timeout_ms = argv[2].parse::<isize>().expect("Error when parsing timeout!");
+    let pid = fork() as usize;
+    if pid == 0 {
+        if exec(argv[1], &[core::ptr::null::<u8>()]) != 0 {
+            println!("Error when executing '{}'", argv[1]);
+            return -4;
+        }
+    } else {
+        let start_time = get_time();
+        let mut child_exited = false;
+        let mut exit_code: i32 = 0;
+        loop {
+            if get_time() - start_time > timeout_ms {
+                break;
+            }
+            if waitpid_nb(pid, &mut exit_code) as usize == pid {
+                child_exited = true;
+                println!(
+                    "child exited in {}ms, exit_code = {}",
+                    get_time() - start_time,
+                    exit_code,
+                );
+            }
+        }
+        if !child_exited {
+            println!("child has run for {}ms, kill it!", timeout_ms); 
+            kill(pid, SignalFlags::SIGINT.bits());
+            assert_eq!(waitpid(pid, &mut exit_code) as usize, pid);
+            println!("exit code of the child is {}", exit_code);
+        }
+    }
+    0
+}