Patch #568235: Add posix.setpgid.
diff --git a/Doc/lib/libos.tex b/Doc/lib/libos.tex
index c02d6a6..ebc3c5c 100644
--- a/Doc/lib/libos.tex
+++ b/Doc/lib/libos.tex
@@ -144,6 +144,12 @@
Availability: \UNIX.
\end{funcdesc}
+\begin{funcdesc}{getpgid}{pid}
+Return the process group id of the process with process id \var{pid}.
+If \var{pid} is 0, the process group id of the current process is
+returned. Availability: \UNIX.
+\end{funcdesc}
+
\begin{funcdesc}{getpgrp}{}
\index{process!group}
Return the id of the current process group.