rexec.3: Document rexec_af()

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

man3/rexec.3

@@ -36,9 +36,9 @@
 .\"
 .\" 2007-12-08, mtk, Converted from mdoc to man macros
 .\"
-.TH REXEC 3 2010-09-10 "Linux" "Linux Programmer's Manual"
+.TH REXEC 3 2012-04-23 "Linux" "Linux Programmer's Manual"
 .SH NAME
-rexec \- return stream to a remote command
+rexec, rfexec_af \- return stream to a remote command
 .SH SYNOPSIS
 .nf
 .BR "#define _BSD_SOURCE" "             /* See feature_test_macros(7) */"
@@ -46,6 +46,10 @@ rexec \- return stream to a remote command
 .sp
 .BI "int rexec(char **" ahost ", int " inport ", char *" user ", "
 .BI "          char *" passwd ", char *" cmd ", int *" fd2p );
+.sp
+.BI "int rexec_af(char **" ahost ", int " inport ", char *" user ", "
+.BI "             char *" passwd ", char *" cmd ", int *" fd2p ,
+.BI "             sa_family_t " af  );
 .fi
 .SH DESCRIPTION
 This interface is obsoleted by
@@ -113,13 +117,35 @@ command) will be made the same as the
 and no
 provision is made for sending arbitrary signals to the remote process,
 although you may be able to get its attention by using out-of-band data.
-.SH "CONFORMING TO"
-Not in POSIX.1-2001.
-Present on the BSDs, Solaris, and many other systems.
+.SS rexec_af()
 The
 .BR rexec ()
-function appeared in
-4.2BSD.
+function works over IPv4
+.RB ( AF_INET ).
+By contrast, the
+.BR rexec_af ()
+function provides an extra argument,
+.IR af ,
+that allows the caller to select the protocol.
+This argument can be specified as
+.BR AF_INET ,
+.BR AF_INET6 ,
+or
+.BR AF_UNSPEC
+(to allow the implementation to select the protocol).
+.SH VERSIONS
+The
+.BR rexec_af ()
+function was added to glibc in version 2.2.
+.SH "CONFORMING TO"
+These functions are not in POSIX.1-2001.
+The
+.BR rexec ()
+function first appeared in
+4.2BSD, and is present on the BSDs, Solaris, and many other systems.
+The
+.BR rexec_af ()
+function is more recent, nad less widespread.
 .SH BUGS
 The
 .BR rexec ()