diff --git a/NEWS.rst b/NEWS.rst
index 1633747..35c1aaf 100644
--- a/NEWS.rst
+++ b/NEWS.rst
@@ -5,7 +5,8 @@ every change, see the Git log.
 
 Latest
 ------
-* tbd
+* Patch: Fix issue where the output of a process was being truncated at 4096
+  bytes.
 
 4.0.0
 -----
diff --git a/examples/quick_start.py b/examples/quick_start.py
index 0454187..c9850f6 100644
--- a/examples/quick_start.py
+++ b/examples/quick_start.py
@@ -93,8 +93,8 @@ def _proc1_stdout(data):
         proc1.match(stdout="10 packets transmitted*", stderr=None)
 
         # Since proc0 is a daemon we automatically kill it when the last
-        # non-daemon process is done. However we can still see the output it
-        # generated.
+        # non-daemon process is done. However we can still see the output
+        # it generated.
         print(f"proc0: {proc0.stdout}")
 
     finally:
diff --git a/src/dummynet/process_monitor.py b/src/dummynet/process_monitor.py
index 9c92261..7fb6b71 100644
--- a/src/dummynet/process_monitor.py
+++ b/src/dummynet/process_monitor.py
@@ -53,6 +53,8 @@ def update_sudo_password():
     cached_sudo_password = os.environ.get("DUMMYNET_SUDO_PASSWD", None)
     if cached_sudo_password:
         # Environment variable was set, use it instead of asking for a password
+        if not cached_sudo_password.endswith("\n"):
+            cached_sudo_password += "\n"
         return
 
     prompt = f"\n[sudo] password for {getpass.getuser()}: "
@@ -78,7 +80,7 @@ class ProcessMonitor:
     class Poller:
         def __init__(self, log):
             self.poller = select.poll()
-            self.fds = {}
+            self.callbacks = {}
             self.log = log
 
         def add_fd(self, fd, callback):
@@ -87,18 +89,24 @@ def add_fd(self, fd, callback):
             # register for them.
             self.poller.register(fd, select.POLLIN)
 
-            self.fds[fd] = callback
+            self.callbacks[fd] = callback
 
             self.log.debug(f"Poller: register process fd {fd}")
 
         def del_fd(self, fd):
             self.poller.unregister(fd)
-            del self.fds[fd]
+            del self.callbacks[fd]
 
             self.log.debug(f"Poller: unregister process fd {fd}")
 
         def read_fd(self, fd):
-            data = os.read(fd, 4096)
+            data = b""
+            while True:
+                chunk = os.read(fd, 4096)  # Read in chunks of 4096 bytes
+                data += chunk
+                if len(chunk) < 4096:
+                    # If we read less than 4096 bytes, we are done
+                    break
 
             if not data:
                 return
@@ -107,7 +115,7 @@ def read_fd(self, fd):
             self.log.debug(f"Poller: data: '{data}'")
 
             # Call the callback
-            self.fds[fd](data.decode(encoding="utf-8", errors="replace"))
+            self.callbacks[fd](data.decode(encoding="utf-8", errors="replace"))
 
         def poll(self, timeout):
             fds = self.poller.poll(timeout)
@@ -129,8 +137,7 @@ def poll(self, timeout):
                     self.del_fd(fd=fd)
 
         def wait_fd(self, fd):
-
-            while fd in self.fds:
+            while fd in self.callbacks:
                 self.poll(timeout=0.1)
 
     class Process:
@@ -161,7 +168,10 @@ def __init__(
             )
 
             # Pipe possible sudo password to the process
-            if sudo and (cached_sudo_password != None):
+            if sudo and (cached_sudo_password is not None):
+                assert cached_sudo_password.endswith(
+                    "\n"
+                )  # Ensure the password ends with a newline as otherwise sudo will hang
                 self.popen.stdin.write(cached_sudo_password)
                 self.popen.stdin.flush()
 
diff --git a/test/test_dummynet.py b/test/test_dummynet.py
index f75fb35..edb7ceb 100644
--- a/test/test_dummynet.py
+++ b/test/test_dummynet.py
@@ -9,6 +9,7 @@
 import pytest
 import os
 
+
 log = logging.getLogger("dummynet")
 log.setLevel(logging.DEBUG)
 
@@ -263,49 +264,137 @@ def test_hostshell_timeout():
         pass
 
 
-@pytest.fixture
-def sad_path():
+def _hostshell_timeout_daemon():
+    # Seperated this in to a function to look like a typical integration
+    # test
 
     # Check if we need to run as sudo
     sudo = os.getuid() != 0
 
+    # Create a process monitor
     process_monitor = ProcessMonitor(log=log)
+
+    # The host shell
     shell = HostShell(log=log, sudo=sudo, process_monitor=process_monitor)
-    net = DummyNet(shell=shell)
 
-    sad_cgroup = net.add_cgroup(
-        name="test_cgroup_sad",
-        shell=shell,
-        log=log,
-        default_path="/sys/fs/cgroup",
-        controllers={"cpu.wrongname": 0, "memory.high": -200000000},
-        pid=12345,
-    )
-    return sad_cgroup
+    # Start a deamon process (those should not exit before the test is over)
+    shell.run_async(cmd="sleep 2", daemon=True)
 
+    # Next we run a blocking command that will timeout
+    # we expect to also be notified that the daemon process exited
+    # prematurely
 
-@pytest.fixture
-def happy_path():
+    shell.run(cmd="sleep 10", timeout=5)
 
-    # Check if we need to run as sudo
-    sudo = os.getuid() != 0
+    # Nothing to do
+    while process_monitor.keep_running():
+        pass
 
+
+def test_hostshell_timeout_daemon():
+
+    # Check that we get a timeout if we run a command that takes too long
+
+    with pytest.raises(ExceptionGroup) as e:
+        _hostshell_timeout_daemon()
+
+    assert e.group_contains(dummynet.TimeoutError)
+    assert e.group_contains(dummynet.DaemonExitError)
+
+
+def test_run_stdout():
+
+    # Create a process monitor
     process_monitor = ProcessMonitor(log=log)
-    shell = HostShell(log=log, sudo=sudo, process_monitor=process_monitor)
-    net = DummyNet(shell=shell)
 
-    happy_cgroup = net.add_cgroup(
-        name="test_cgroup_happy",
-        shell=shell,
-        log=log,
-        default_path="/sys/fs/cgroup",
-        controllers={"cpu.max": 0.5, "memory.high": 200000000},
-        pid=os.getpid(),
-    )
-    return happy_cgroup
+    # The host shell used if we don't have a recording
+    shell = HostShell(log=log, sudo=False, process_monitor=process_monitor)
+    message = "Hello World"
+    info = shell.run(cmd=f"echo '{message}'")
+
+    assert len(info.stdout) == len(message) + 1
+    assert info.stdout == f"{message}\n"
+
+    long_message = "A" * 4096
+
+    info = shell.run(cmd=f"echo '{long_message}'")
+
+    assert len(info.stdout) == 4096 + 1
+    assert info.stdout == f"{long_message}\n"
+
+    very_long_message = "A" * 4096 * 10
+
+    info = shell.run(cmd=f"echo '{very_long_message}'")
+
+    assert len(info.stdout) == 4096 * 10 + 1
+    assert info.stdout == f"{very_long_message}\n"
+
+    # check timeout of function with a long message
+    with pytest.raises(dummynet.TimeoutError):
+        shell.run(cmd=f"sleep 10; echo '{very_long_message}'", timeout=1)
+
+
+def test_run_async_output():
+
+    process_monitor = ProcessMonitor(log=log)
+
+    shell = HostShell(log=log, sudo=False, process_monitor=process_monitor)
+
+    out1 = shell.run_async(cmd="ping -i 0.1 -c 5 127.0.0.1")
+    out2 = shell.run_async(cmd="ping -i 0.1 -c 3 127.0.0.1")
+
+    out1.stdout_callback = lambda data: print("stdout1: {}".format(data))
+    out2.stdout_callback = lambda data: print("stdout2: {}".format(data))
+
+    while process_monitor.keep_running():
+        pass
+
+    out1.match(stdout="5 packets transmitted*", stderr=None)
+    out2.match(stdout="3 packets transmitted*", stderr=None)
 
 
 # @todo re-enable this test
+# @pytest.fixture
+# def sad_path():
+
+#     # Check if we need to run as sudo
+#     sudo = os.getuid() != 0
+
+#     process_monitor = ProcessMonitor(log=log)
+#     shell = HostShell(log=log, sudo=sudo, process_monitor=process_monitor)
+#     net = DummyNet(shell=shell)
+
+#     sad_cgroup = net.add_cgroup(
+#         name="test_cgroup_sad",
+#         shell=shell,
+#         log=log,
+#         default_path="/sys/fs/cgroup",
+#         controllers={"cpu.wrongname": 0, "memory.high": -200000000},
+#         pid=12345,
+#     )
+#     return sad_cgroup
+
+
+# @pytest.fixture
+# def happy_path():
+
+#     # Check if we need to run as sudo
+#     sudo = os.getuid() != 0
+
+#     process_monitor = ProcessMonitor(log=log)
+#     shell = HostShell(log=log, sudo=sudo, process_monitor=process_monitor)
+#     net = DummyNet(shell=shell)
+
+#     happy_cgroup = net.add_cgroup(
+#         name="test_cgroup_happy",
+#         shell=shell,
+#         log=log,
+#         default_path="/sys/fs/cgroup",
+#         controllers={"cpu.max": 0.5, "memory.high": 200000000},
+#         pid=os.getpid(),
+#     )
+#     return happy_cgroup
+
 # def test_cgroup_build(happy_path):
 #     cgroup_build = happy_path
 
@@ -381,41 +470,3 @@ def happy_path():
 #         cgroup_cleanup.hard_clean()
 #     except dummynet.errors.RunInfoError as e:
 #         assert "No such file or directory" in str(e)
-
-
-def _hostshell_timeout_daemon():
-    # Seperated this in to a function to look like a typical integration
-    # test
-
-    # Check if we need to run as sudo
-    sudo = os.getuid() != 0
-
-    # Create a process monitor
-    process_monitor = ProcessMonitor(log=log)
-
-    # The host shell
-    shell = HostShell(log=log, sudo=sudo, process_monitor=process_monitor)
-
-    # Start a deamon process (those should not exit before the test is over)
-    shell.run_async(cmd="sleep 2", daemon=True)
-
-    # Next we run a blocking command that will timeout
-    # we expect to also be notified that the daemon process exited
-    # prematurely
-
-    shell.run(cmd="sleep 10", timeout=5)
-
-    # Nothing to do
-    while process_monitor.keep_running():
-        pass
-
-
-def test_hostshell_timeout_daemon():
-
-    # Check that we get a timeout if we run a command that takes too long
-
-    with pytest.raises(ExceptionGroup) as e:
-        _hostshell_timeout_daemon()
-
-    assert e.group_contains(dummynet.TimeoutError)
-    assert e.group_contains(dummynet.DaemonExitError)
diff --git a/wscript b/wscript
index 8439790..c9ff48d 100644
--- a/wscript
+++ b/wscript
@@ -25,6 +25,12 @@ def options(opt):
         "--run_tests", default=False, action="store_true", help="Run all unit tests"
     )
 
+    gr.add_option(
+        "--filter",
+        default=None,
+        help='Select tests based on their name. E.g. "test_run_stdout"',
+    )
+
     gr.add_option(
         "--pytest_basetemp",
         default="pytest_temp",
@@ -44,6 +50,7 @@ def build(bld):
     # Create a virtualenv in the source folder and build universal wheel
     with bld.create_virtualenv() as venv:
 
+        venv.run(cmd="python -m pip install setuptools")
         venv.run(cmd="python -m pip install wheel")
         venv.run(cmd="python setup.py bdist_wheel --universal", cwd=bld.path)
 
@@ -122,7 +129,7 @@ def _pytest(bld):
         _pytest_dev(bld=bld)
 
     else:
-        _pytest_run(bld=bld)
+        _pytest_run(ctx=bld)
 
 
 def _pytest_dev(bld):
@@ -131,13 +138,13 @@ def _pytest_dev(bld):
     venv.run("python -m pip install -e .")
 
 
-def _pytest_run(bld):
+def _pytest_run(ctx):
 
-    venv = bld.create_virtualenv(overwrite=True)
+    venv = ctx.create_virtualenv(overwrite=True)
     venv.run("python -m pip install -r test/requirements.txt")
 
     # Install the dummynet plugin in the virtualenv
-    wheel = _find_wheel(ctx=bld)
+    wheel = _find_wheel(ctx=ctx)
 
     venv.run(f"python -m pip install {wheel}")
 
@@ -147,7 +154,7 @@ def _pytest_run(bld):
     # We override the pytest temp folder with the basetemp option,
     # so the test folders will be available at the specified location
     # on all platforms. The default location is the "pytest" local folder.
-    basetemp = os.path.abspath(os.path.expanduser(bld.options.pytest_basetemp))
+    basetemp = os.path.abspath(os.path.expanduser(ctx.options.pytest_basetemp))
 
     # We need to manually remove the previously created basetemp folder,
     # because pytest uses os.listdir in the removal process, and that fails
@@ -155,15 +162,12 @@ def _pytest_run(bld):
     if os.path.exists(basetemp):
         waflib.extras.wurf.directory.remove_directory(path=basetemp)
 
-    # Run all tests by just passing the test directory. Specific tests can
-    # be enabled by specifying the full path e.g.:
-    #
-    #     'test/test_run.py::test_create_context'
-    #
-    test_filter = "test"
+    test_filter = ""
+    if ctx.options.filter:
+        test_filter = f"-k '{ctx.options.filter}'"
 
     # Main test command
-    venv.run(f"python -B -m pytest {test_filter} --basetemp {basetemp}")
+    venv.run(f"python -B -m pytest -xrA {test_filter} --basetemp {basetemp}")
 
     # Check the package
     venv.run(f"twine check {wheel}")