style: align ruff across all plugins and tools

Run ruff across the full `check-plugins/` and `tools/` tree with the
rule set already in pyproject.toml (B, C4, E, F, I, RUF, SIM, UP, W).
This clears ~400 accumulated violations so that `tools/run-static-checks`
can be used as a trustworthy gate going forward.

Categories fixed:

- I001 (324): import blocks normalized (order, grouping, blank lines).
- RUF059 (145): discarded tuple-unpack slots prefixed with `_` (`success, result = ...` ->
  `_success, result = ...`) so the intent is explicit and shadowing is visible.
- UP032 (30): `.format()` calls converted to f-strings.
- F401 (9): unused imports removed.
- RUF005 (8): `[x] + list` rewritten as `[x, *list]`.
- RUF100 (6): unused `# noqa` directives removed.
- E713/E714 (7): `not x in y` and `not x is y` rewritten to `x not in y` / `x is not y`.
- F541 (5): empty f-strings demoted to regular strings.
- SIM401/118/115/108/101, RUF015/019 and a few other ruff suggestions.

Manual fixes that ruff could not auto-apply:

- E402 (39): 7 plugins had the `warnings.filterwarnings()` pattern
  or an `import lib.smb` try/except in the middle of their import
  block, which pushed all following imports past ruff's "module level
  imports at top" rule. Reordered so all unconditional imports sit
  first and the `warnings.filterwarnings()` / optional-lib try/except
  blocks come after. about-me no longer imports pymysql at all, so
  the stale filterwarnings call was dropped.
- F403/F405 (8): `from lib.globals import *` in `ping/unit-test/run`
  replaced with the explicit set of STATE_* names actually used.
- E741 (5): single-letter variable `l` in basket-compare's compare_*
  helpers renamed to `left_item` for readability.
- F821 (1): basket-compare referenced `STATE_UNKNOWN` without
  importing it; the import was added. This was a latent bug that
  would have crashed `sys.exit(STATE_UNKNOWN)` on any argparse
  SystemExit.
- B007 (1): unused loop variable `value` in check2basket replaced
  with `for key in parent_value`.
- RUF001 (5): ambiguous Unicode characters in DESCRIPTION strings and
  comments (typographic minus/apostrophes/hyphens) replaced with
  plain ASCII.
- SIM115 (1): path-rw-test's `tempfile.TemporaryFile()` now uses a
  context manager.

Plugin fixes worth calling out:

- scanrootkit: kernel symbol matching was already tightened in the
  previous commit; this pass also fixes the long-standing dead-code
  directory check (covered in the scanrootkit commit that precedes
  this one).
- Several plugins' inline `os.path.isfile()` checks that were
  actually intended to test for directories are left alone for now
  and tracked separately - this commit is scoped to style.

Also: aligned the ruff `ignore` list in `pyproject.toml` with the
equivalent list in the shared `lib` repo by adding `RUF002`, `RUF003`,
`SIM102` and `SIM105`, so the same style expectations hold in both
codebases.

No behavior change intended. Style-only, per the house rule that
pure style passes do not bump plugin `__version__`.

Author: markuslf

check-plugins/about-me/about-me

@@ -10,10 +10,6 @@
 
 """See the check's README for more details."""
 
-import warnings
-
-warnings.filterwarnings('ignore', category=UserWarning, module='pymysql')
-
 import argparse
 import os
 import re
@@ -137,7 +133,7 @@ def get_birthday():
         return f'born {lib.time.epoch2iso(birthday.st_ctime)}. '
     # no way to do this in python - getting the birthday of a folder
     # hardcoded shell pipeline (no user input); shell=True needed for pipes
-    success, result = lib.shell.shell_exec(
+    _success, result = lib.shell.shell_exec(
         'stat / | grep "Birth" | sed "s/Birth: //g" | cut -b 2-11',
         shell=True,  # nosec B604
     )
@@ -1346,10 +1342,7 @@ def main():
     if firmware_device_model:
         msg += f'{firmware_device_model}, '
 
-    if args.DMIDECODE:
-        dmi = lib.dmidecode.get_data()
-    else:
-        dmi = False
+    dmi = lib.dmidecode.get_data() if args.DMIDECODE else False
     sys_dimensions = get_sys_dimensions()
     if dmi and sys_dimensions:
         # combine the best from both worlds

check-plugins/apache-httpd-status/apache-httpd-status

@@ -152,7 +152,7 @@ def main():
             lib.base.cu('Malformed Apache server info.')
     else:
         # do not call the command, put in test data
-        stdout, stderr, retc = lib.lftest.test(args.TEST)
+        stdout, _stderr, _retc = lib.lftest.test(args.TEST)
         result = stdout
     result = result.strip().split('\n')
 

check-plugins/apache-httpd-status/unit-test/run

@@ -14,9 +14,8 @@ import unittest
 
 sys.path.insert(0, '..')
 
-from lib.globals import STATE_OK, STATE_WARN
 import lib.lftest
-
+from lib.globals import STATE_OK, STATE_WARN
 
 CACHE_DB = '/tmp/linuxfabrik-monitoring-plugins-apache-httpd-status.db'
 

check-plugins/apache-httpd-version/unit-test/run

@@ -25,13 +25,13 @@ the day Apache 2.4 hits EOL or a 2.6 cycle appears.
 """
 
 import sys
+
 sys.path.insert(0, '..')
 
 import unittest
 
-from lib.globals import STATE_OK, STATE_UNKNOWN
 import lib.lftest
-
+from lib.globals import STATE_OK, STATE_UNKNOWN
 
 TESTS = [
     {

check-plugins/apache-solr-version/unit-test/run

@@ -29,13 +29,13 @@ re-pinned every few months.
 """
 
 import sys
+
 sys.path.insert(0, '..')
 
 import unittest
 
-from lib.globals import STATE_OK, STATE_UNKNOWN, STATE_WARN
 import lib.lftest
-
+from lib.globals import STATE_OK, STATE_UNKNOWN, STATE_WARN
 
 TESTS = [
     {

check-plugins/atlassian-statuspage/unit-test/run

@@ -9,13 +9,13 @@
 # https://github.com/Linuxfabrik/monitoring-plugins/blob/main/CONTRIBUTING.md
 
 import sys
+
 sys.path.insert(0, '..')
 
 import unittest
 
-from lib.globals import STATE_CRIT, STATE_OK, STATE_WARN
 import lib.lftest
-
+from lib.globals import STATE_CRIT, STATE_OK, STATE_WARN
 
 # Fixtures were captured from real Atlassian-Statuspage-powered pages:
 #

check-plugins/axenita-stats/unit-test/run

@@ -15,9 +15,9 @@ sys.path.insert(0, '..')  # Adds higher directory to python modules path.
 
 import unittest
 
-from lib.globals import STATE_OK, STATE_UNKNOWN, STATE_WARN, STATE_CRIT
 import lib.base
 import lib.shell
+from lib.globals import STATE_OK, STATE_WARN
 
 
 class TestCheck(unittest.TestCase):

check-plugins/by-ssh/by-ssh

@@ -16,13 +16,12 @@ import sys
 
 import lib.args
 import lib.base
-import lib.shell
 import lib.lftest
+import lib.shell
 import lib.time
 import lib.txt
 from lib.globals import STATE_CRIT, STATE_OK, STATE_UNKNOWN, STATE_WARN
 
-
 __author__ = 'Linuxfabrik GmbH, Zurich/Switzerland'
 __version__ = '2026040801'
 

check-plugins/by-winrm/by-winrm

@@ -21,7 +21,6 @@ import lib.time
 import lib.winrm
 from lib.globals import STATE_CRIT, STATE_OK, STATE_UNKNOWN, STATE_WARN
 
-
 __author__ = 'Linuxfabrik GmbH, Zurich/Switzerland'
 __version__ = '2026033101'
 

check-plugins/cometsystem/cometsystem

@@ -11,16 +11,15 @@
 """See the check's README for more details."""
 
 import argparse
-import sys
 import json
+import sys
 
 import lib.args
 import lib.base
 import lib.lftest
 import lib.url
 from lib.globals import STATE_CRIT, STATE_OK, STATE_UNKNOWN, STATE_WARN
 
-
 __author__ = """Linuxfabrik GmbH, Zurich/Switzerland;
                 originally written by Dominik Riva, Universitätsspital Basel/Switzerland"""
 __version__ = '2026040801'
@@ -174,7 +173,7 @@ def main():
         )
     else:
         # do not call the command, put in test data
-        stdout, stderr, retc = lib.lftest.test(args.TEST)
+        stdout, _stderr, _retc = lib.lftest.test(args.TEST)
         result = json.loads(stdout)
     if 'ch1' not in result:
         lib.base.cu('Malformed Comet System Web Sensors status file.')