closes bpo-38713: Expose P_PIDFD in os if it's defined. (GH-17071)
https://bugs.python.org/issue38713
diff --git a/Doc/library/os.rst b/Doc/library/os.rst
index 9c907a7..48bd6b9 100644
--- a/Doc/library/os.rst
+++ b/Doc/library/os.rst
@@ -3921,7 +3921,8 @@
.. function:: waitid(idtype, id, options)
Wait for the completion of one or more child processes.
- *idtype* can be :data:`P_PID`, :data:`P_PGID` or :data:`P_ALL`.
+ *idtype* can be :data:`P_PID`, :data:`P_PGID`, :data:`P_ALL`, or
+ :data:`P_PIDFD` on Linux.
*id* specifies the pid to wait on.
*options* is constructed from the ORing of one or more of :data:`WEXITED`,
:data:`WSTOPPED` or :data:`WCONTINUED` and additionally may be ORed with
@@ -3946,6 +3947,15 @@
.. versionadded:: 3.3
+.. data:: P_PIDFD
+
+ This is a Linux-specific *idtype* that indicates that *id* is a file
+ descriptor that refers to a process.
+
+ .. availability:: Linux 5.4+
+
+ .. versionadded:: 3.9
+
.. data:: WEXITED
WSTOPPED
WNOWAIT