diff --git a/chatmaild/src/chatmaild/tests/plugin.py b/chatmaild/src/chatmaild/tests/plugin.py
index b57418a3..165de3e0 100644
--- a/chatmaild/src/chatmaild/tests/plugin.py
+++ b/chatmaild/src/chatmaild/tests/plugin.py
@@ -85,13 +85,13 @@ def mockout():
         captured_green = []
         captured_plain = []
 
-        def red(self, msg):
+        def red(self, msg, **kw):
             self.captured_red.append(msg)
 
-        def green(self, msg):
+        def green(self, msg, **kw):
             self.captured_green.append(msg)
 
-        def __call__(self, msg):
+        def print(self, msg="", **kw):
             self.captured_plain.append(msg)
 
     return MockOut()
diff --git a/cmdeploy/src/cmdeploy/tests/test_util.py b/cmdeploy/src/cmdeploy/tests/test_util.py
new file mode 100644
index 00000000..b1f22ef2
--- /dev/null
+++ b/cmdeploy/src/cmdeploy/tests/test_util.py
@@ -0,0 +1,120 @@
+import sys
+
+from cmdeploy.util import Out, collapse, get_git_hash, get_version_string, shell
+
+
+class TestOut:
+    def test_prefix_default(self, capsys):
+        out = Out()
+        out.print("hello")
+        assert capsys.readouterr().out == "hello\n"
+
+    def test_prefix_custom(self, capsys):
+        out = Out(prefix=">> ")
+        out.print("hello")
+        assert capsys.readouterr().out == ">> hello\n"
+
+    def test_prefix_print_file(self):
+        import io
+
+        buf = io.StringIO()
+        out = Out(prefix=":: ")
+        out.print("msg", file=buf)
+        assert ":: msg" in buf.getvalue()
+
+    def test_new_prefixed_out(self, capsys):
+        parent = Out(prefix="A")
+        child = parent.new_prefixed_out("B")
+        child.print("x")
+        assert capsys.readouterr().out == "ABx\n"
+        # shares section_timings
+        assert child.section_timings is parent.section_timings
+
+    def test_section_no_auto_indent(self, capsys):
+        out = Out(prefix="")
+        with out.section("test"):
+            out.print("inside")
+        captured = capsys.readouterr().out
+        # "inside" should NOT be indented by section()
+        lines = captured.strip().splitlines()
+        inside_line = [l for l in lines if "inside" in l][0]
+        assert inside_line == "inside"
+
+    def test_section_records_timing(self):
+        out = Out()
+        with out.section("s1"):
+            pass
+        assert len(out.section_timings) == 1
+        assert out.section_timings[0][0] == "s1"
+
+    def test_shell_failure_shows_output(self):
+        """When a shell command fails, its output and exit code are shown."""
+        import subprocess
+
+        result = subprocess.run(
+            [
+                sys.executable,
+                "-c",
+                "from cmdeploy.util import Out; Out(prefix='').shell("
+                "\"echo 'boom on stderr' >&2; exit 42\")",
+            ],
+            capture_output=True,
+            text=True,
+            check=False,
+        )
+        # the command's stderr is merged into stdout by Popen
+        assert "boom on stderr" in result.stdout
+        # Out.red() prints the failure notice to stderr
+        assert "exit code 42" in result.stderr
+
+
+def test_collapse():
+    text = """
+        line 1
+        line 2
+    """
+    assert collapse(text) == "line 1 line 2"
+    assert collapse("  single line  ") == "single line"
+
+
+def test_git_helpers_no_git(tmp_path):
+    # Not a git repo
+    assert get_git_hash(root=tmp_path) is None
+    assert get_version_string(root=tmp_path) == "unknown"
+
+
+def test_git_helpers_empty_repo(tmp_path):
+    shell("git init", cwd=tmp_path, check=True)
+    # No commits yet
+    assert get_git_hash(root=tmp_path) is None
+    assert get_version_string(root=tmp_path) == "unknown"
+
+
+def test_git_helpers_with_commits_and_diffs(tmp_path):
+    shell("git init", cwd=tmp_path, check=True)
+    shell("git config user.email you@example.com", cwd=tmp_path, check=True)
+    shell("git config user.name 'Your Name'", cwd=tmp_path, check=True)
+
+    # First commit
+    path = tmp_path / "file.txt"
+    path.write_text("content")
+    shell("git add file.txt", cwd=tmp_path, check=True)
+    shell("git commit -m initial", cwd=tmp_path, check=True)
+
+    git_hash = get_git_hash(root=tmp_path)
+    assert len(git_hash) >= 7  # usually 40, but git is git
+    assert get_version_string(root=tmp_path) == git_hash
+
+    # Create a diff
+    path.write_text("new content")
+    v = get_version_string(root=tmp_path)
+    assert v.startswith(git_hash + "\n")
+    assert "new content" in v
+    assert not v.endswith("\n")
+
+    # Commit again -> no diff
+    shell("git add file.txt", cwd=tmp_path, check=True)
+    shell("git commit -m second", cwd=tmp_path, check=True)
+    new_hash = get_git_hash(root=tmp_path)
+    assert new_hash != git_hash
+    assert get_version_string(root=tmp_path) == new_hash
diff --git a/cmdeploy/src/cmdeploy/util.py b/cmdeploy/src/cmdeploy/util.py
new file mode 100644
index 00000000..4a5178b7
--- /dev/null
+++ b/cmdeploy/src/cmdeploy/util.py
@@ -0,0 +1,169 @@
+"""Shared utility functions for cmdeploy."""
+
+import os
+import shutil
+import subprocess
+import sys
+import textwrap
+import time
+from contextlib import contextmanager
+from pathlib import Path
+
+from termcolor import colored
+
+
+class Out:
+    """Convenience output printer providing coloring and section formatting."""
+
+    def __init__(self, prefix="", verbosity=0):
+        self.section_timings = []
+        self.prefix = prefix
+        self.sepchar = "\u2501"
+        self.verbosity = verbosity
+        env_width = os.environ.get("_CMDEPLOY_WIDTH")
+        if env_width:
+            self.section_width = int(env_width)
+        else:
+            self.section_width = shutil.get_terminal_size((80, 24)).columns
+
+    def new_prefixed_out(self, newprefix="  "):
+        """Return a new Out with an extended prefix,
+        sharing section_timings with the parent.
+        """
+        out = Out(
+            prefix=self.prefix + newprefix,
+            verbosity=self.verbosity,
+        )
+        out.section_timings = self.section_timings
+        return out
+
+    def red(self, msg, file=sys.stderr):
+        print(colored(self.prefix + msg, "red"), file=file, flush=True)
+
+    def green(self, msg, file=sys.stderr):
+        print(colored(self.prefix + msg, "green"), file=file, flush=True)
+
+    def print(self, msg="", **kwargs):
+        """Print to stdout with automatic flush."""
+        if msg:
+            msg = self.prefix + msg
+        print(msg, flush=True, **kwargs)
+
+    def _format_header(self, title):
+        """Return a formatted section header string."""
+        width = self.section_width - len(self.prefix)
+        bar = self.sepchar * (width - len(title) - 5)
+        return f"{self.sepchar * 3} {title} {bar}"
+
+    @contextmanager
+    def section(self, title):
+        """Context manager that prints a section header and records elapsed time."""
+        self.green(self._format_header(title))
+        t0 = time.time()
+        yield
+        elapsed = time.time() - t0
+        self.section_timings.append((title, elapsed))
+
+    def section_line(self, title):
+        """Print a section header without timing."""
+        self.green(self._format_header(title))
+
+    def shell(self, cmd, quiet=False, **kwargs):
+        """Print *cmd*, run it, and re-print its output with the current prefix.
+
+        *cmd* is passed through :func:`collapse`, so callers
+        can use triple-quoted f-strings freely.
+        Stdout and stderr are merged, read line-by-line,
+        and each line is printed with ``self.prefix`` prepended.
+        When the command exits non-zero, a red error line is printed.
+        """
+        cmd = collapse(cmd)
+        if not quiet:
+            self.print(f"$ {cmd}")
+        indent = self.prefix + "  "
+        env = kwargs.pop("env", None)
+        if env is None:
+            env = os.environ.copy()
+        env["_CMDEPLOY_WIDTH"] = str(self.section_width - len(indent))
+        proc = subprocess.Popen(
+            cmd,
+            shell=True,
+            text=True,
+            stdin=subprocess.DEVNULL,
+            stdout=subprocess.PIPE,
+            stderr=subprocess.STDOUT,
+            env=env,
+            **kwargs,
+        )
+        for line in proc.stdout:
+            sys.stdout.write(indent + line)
+            sys.stdout.flush()
+        ret = proc.wait()
+        if ret:
+            self.red(f"command failed with exit code {ret}: {cmd}")
+        return ret
+
+
+def _project_root():
+    """Return the project root directory."""
+    return Path(__file__).resolve().parent.parent.parent.parent
+
+
+def collapse(text):
+    """Dedent, join lines, and strip a (triple-quoted) string.
+
+    Handy for writing shell commands across multiple lines::
+
+        cmd = collapse(f\"""
+            cmdeploy run
+            --config {ct.ini}
+            --ssh-host {ct.domain}
+        \""")
+    """
+    return textwrap.dedent(text).replace("\n", " ").strip()
+
+
+def shell(cmd, check=False, **kwargs):
+    """Run a shell command string with sensible defaults.
+
+    *cmd* is passed through :func:`collapse` first, so callers
+    can use triple-quoted f-strings freely.
+    Captures stdout/stderr by default; pass ``capture_output=False``
+    to stream output to the terminal instead.
+    """
+    if "capture_output" not in kwargs and "stdout" not in kwargs:
+        kwargs["capture_output"] = True
+    kwargs.setdefault("stdin", subprocess.DEVNULL)
+    return subprocess.run(collapse(cmd), shell=True, text=True, check=check, **kwargs)
+
+
+def get_git_hash(root=None):
+    """Return the local HEAD commit hash, or None."""
+    if root is None:
+        root = _project_root()
+    result = shell(
+        "git rev-parse HEAD",
+        cwd=str(root),
+    )
+    if result.returncode == 0:
+        return result.stdout.strip()
+    return None
+
+
+def get_version_string(root=None):
+    """Return ``git_hash\\ngit_diff`` for the local working tree.
+
+    Used by :class:`~cmdeploy.deployers.GithashDeployer` to write
+    ``/etc/chatmail-version`` and by ``lxc-status`` to compare
+    the deployed state against the local checkout.
+    """
+    if root is None:
+        root = _project_root()
+    git_hash = get_git_hash(root=root) or "unknown"
+    try:
+        git_diff = shell("git diff", cwd=str(root)).stdout.strip()
+    except Exception:
+        git_diff = ""
+    if git_diff:
+        return f"{git_hash}\n{git_diff}"
+    return git_hash