Add support for AIX (closes #241)

distro.py

@@ -219,6 +219,7 @@ def id() -> str:
     "freebsd"       FreeBSD
     "midnightbsd"   MidnightBSD
     "rocky"         Rocky Linux
+    "aix"           AIX
     ==============  =========================================
 
     If you have a need to get distros for reliable IDs added into this set,
@@ -752,7 +753,8 @@ def __repr__(self) -> str:
             "_os_release_info={self._os_release_info!r}, "
             "_lsb_release_info={self._lsb_release_info!r}, "
             "_distro_release_info={self._distro_release_info!r}, "
-            "_uname_info={self._uname_info!r})".format(self=self)
+            "_uname_info={self._uname_info!r}, "
+            "_oslevel_info={self._oslevel_info!r})".format(self=self)
         )
 
     def linux_distribution(
@@ -840,6 +842,9 @@ def version(self, pretty: bool = False, best: bool = False) -> str:
             ).get("version_id", ""),
             self.uname_attr("release"),
         ]
+        if self.uname_attr("id").startswith("aix"):
+            # On AIX platforms, prefer oslevel command output.
+            versions.insert(0, self.oslevel_info())
         version = ""
         if best:
             # This algorithm uses the last version in priority order that has
@@ -980,6 +985,12 @@ def uname_info(self) -> Dict[str, str]:
         """
         return self._uname_info
 
+    def oslevel_info(self) -> str:
+        """
+        Return AIX' oslevel command output.
+        """
+        return self._oslevel_info
+
     def os_release_attr(self, attribute: str) -> str:
         """
         Return a single named information item from the os-release file data
@@ -1139,6 +1150,14 @@ def _uname_info(self) -> Dict[str, str]:
         content = self._to_str(stdout).splitlines()
         return self._parse_uname_content(content)
 
+    @cached_property
+    def _oslevel_info(self) -> str:
+        try:
+            stdout = subprocess.check_output("oslevel", stderr=subprocess.DEVNULL)
+        except (OSError, subprocess.CalledProcessError):
+            return ""
+        return self._to_str(stdout).strip()
+
     @staticmethod
     def _parse_uname_content(lines: Sequence[str]) -> Dict[str, str]:
         if not lines:

tests/resources/distros/aix72/bin/oslevel

@@ -0,0 +1,3 @@
+#!/bin/sh
+
+echo "7.2.0.0"

tests/resources/distros/aix72/bin/uname

@@ -0,0 +1,3 @@
+#!/bin/sh
+
+echo "AIX 2"

tests/test_distro.py

@@ -1128,6 +1128,20 @@ def test_arch_release(self) -> None:
         # considered a valid distro release file:
         self._test_non_existing_release_file()
 
+    def test_aix72_release(self) -> None:
+        desired_outcome = {
+            "id": "aix",
+            "name": "AIX",
+            "pretty_name": "AIX 7.2.0.0",
+            "version": "7.2.0.0",
+            "pretty_version": "7.2.0.0",
+            "best_version": "7.2.0.0",
+            "major_version": "7",
+            "minor_version": "2",
+            "build_number": "0",
+        }
+        self._test_outcome(desired_outcome)
+
     def test_centos5_release(self) -> None:
         desired_outcome = {
             "id": "centos",