feat(disk): add shorten_path() for zsh-style path abbreviation

Reduce every parent path component to its first character while keeping
the basename in full, the way the zsh prompt shortens a long working
directory. Pure string transform, no filesystem access. Unit-tested.

Author: markuslf

CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+* disk.py: `shorten_path()` abbreviates a path for display by reducing every parent component to its first character (zsh-style), keeping the basename in full
 * redfish.py: `get_auth_header()` builds the request authentication header, reusing a cached session token to avoid creating a new controller session on every request, and falling back to HTTP Basic auth
 * redfish.py: `get_chassis_power_powercontrol()` parses a power control (overall power consumption) entry for health monitoring and reporting
 * redfish.py: `get_manager()` parses a manager (BMC) resource for health monitoring and identification

disk.py

@@ -13,7 +13,7 @@
 """
 
 __author__ = 'Linuxfabrik GmbH, Zurich/Switzerland'
-__version__ = '2026060601'
+__version__ = '2026060801'
 
 import csv
 import os
@@ -693,6 +693,36 @@ def rm_file(filename):
         return False, f'Unknown error deleting {filename}: {e}'
 
 
+def shorten_path(path):
+    """
+    Shorten a path for display.
+
+    Abbreviate a slash-separated path by reducing every component except the last one to its
+    first character, the way the zsh prompt shortens a long working directory. The last
+    component is kept in full because it usually carries the identifying information. This is
+    a pure string transformation; the path is not resolved and the filesystem is not touched.
+
+    ### Parameters
+    - **path** (`str`): A slash-separated path, for example `/etc/pki/tls/certs/002c0b4f.0`.
+
+    ### Returns
+    - **str**: The abbreviated path, for example `/e/p/t/c/002c0b4f.0`. A value without a
+      slash (a bare basename, an empty string, a sentinel like `-`) is returned unchanged.
+
+    ### Example
+    >>> shorten_path('/etc/pki/tls/certs/002c0b4f.0')
+    '/e/p/t/c/002c0b4f.0'
+
+    >>> shorten_path('index.php')
+    'index.php'
+    """
+    if not path or '/' not in path:
+        return path
+    head, _, tail = path.rpartition('/')
+    abbrev = '/'.join(part[:1] for part in head.split('/'))
+    return f'{abbrev}/{tail}'
+
+
 def udevadm(device, _property):
     """
     Run `udevadm info` and extract a specific property manually.

tests/disk/unit-test/run

@@ -112,7 +112,9 @@ class TestTreeOps(unittest.TestCase):
         disk.write_file(os.path.join(src, 'a.txt'), 'x')
 
         dst_file = os.path.join(self.base, 'a-copy.txt')
-        self.assertEqual(disk.copy_file(os.path.join(src, 'a.txt'), dst_file), (True, None))
+        self.assertEqual(
+            disk.copy_file(os.path.join(src, 'a.txt'), dst_file), (True, None)
+        )
         self.assertTrue(os.path.isfile(dst_file))
 
         dst_dir = os.path.join(self.base, 'dst')
@@ -146,5 +148,34 @@ class TestHostHelpers(unittest.TestCase):
         self.assertIsInstance(disk.get_block_devices(), list)
 
 
+class TestShortenPath(unittest.TestCase):
+    def test_abbreviates_parents_keeps_basename(self):
+        self.assertEqual(
+            disk.shorten_path('/etc/pki/tls/certs/002c0b4f.0'),
+            '/e/p/t/c/002c0b4f.0',
+        )
+        self.assertEqual(
+            disk.shorten_path('/usr/share/icingaweb2/public/index.php'),
+            '/u/s/i/p/index.php',
+        )
+
+    def test_two_segment_path(self):
+        self.assertEqual(disk.shorten_path('/srv/index.php'), '/s/index.php')
+
+    def test_top_level_file_stays(self):
+        self.assertEqual(disk.shorten_path('/index.php'), '/index.php')
+
+    def test_relative_path(self):
+        self.assertEqual(disk.shorten_path('relative/path/file'), 'r/p/file')
+
+    def test_no_slash_passthrough(self):
+        self.assertEqual(disk.shorten_path('index.php'), 'index.php')
+        self.assertEqual(disk.shorten_path('-'), '-')
+        self.assertEqual(disk.shorten_path(''), '')
+
+    def test_root_stays(self):
+        self.assertEqual(disk.shorten_path('/'), '/')
+
+
 if __name__ == '__main__':
     unittest.main()