accept.2, bind.2, connect.2, getpeername.2, getsockname.2, getsockopt.2, listen.2, recv.2, send.2, shutdown.2: ERRORS: standardize error text for ENOTSOCK error

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

man2/accept.2

@@ -260,7 +260,9 @@ This often means that the memory allocation is limited by the socket buffer
 limits, not by the system memory.
 .TP
 .B ENOTSOCK
-The descriptor references a file, not a socket.
+The file descriptor
+.I sockfd
+does not refer to a socket.
 .TP
 .B EOPNOTSUPP
 The referenced socket is not of type

man2/bind.2

@@ -190,8 +190,9 @@ is wrong, or
 is not a valid address for this socket's domain.
 .TP
 .B ENOTSOCK
+The file descriptor
 .I sockfd
-is a descriptor for a file, not a socket.
+does not refer to a socket.
 .PP
 The following errors are specific to UNIX domain
 .RB ( AF_UNIX )

man2/connect.2

@@ -221,7 +221,9 @@ The socket is already connected.
 Network is unreachable.
 .TP
 .B ENOTSOCK
-The file descriptor is not associated with a socket.
+The file descriptor
+.I sockfd
+does not refer to a socket.
 .TP
 .B EPROTOTYPE
 The socket type does not support the requested communications protocol.

man2/getpeername.2

@@ -95,9 +95,9 @@ to perform the operation.
 The socket is not connected.
 .TP
 .B ENOTSOCK
-The argument
+The file descriptor
 .I sockfd
-is a file, not a socket.
+does not refer to a socket.
 .SH CONFORMING TO
 POSIX.1-2001, POSIX.1-2008, SVr4, 4.4BSD
 .RB ( getpeername ()

man2/getsockname.2

@@ -91,9 +91,9 @@ Insufficient resources were available in the system
 to perform the operation.
 .TP
 .B ENOTSOCK
-The argument
+The file descriptor
 .I sockfd
-is a file, not a socket.
+does not refer to a socket.
 .SH CONFORMING TO
 POSIX.1-2001, POSIX.1-2008, SVr4, 4.4BSD
 .RB ( getsockname ()

man2/getsockopt.2

@@ -169,9 +169,9 @@ option described in
 The option is unknown at the level indicated.
 .TP
 .B ENOTSOCK
-The argument
+The file descriptor
 .I sockfd
-is a file, not a socket.
+does not refer to a socket.
 .SH CONFORMING TO
 POSIX.1-2001, POSIX.1-2008,
 SVr4, 4.4BSD (these system calls first appeared in 4.2BSD).

man2/listen.2

@@ -108,9 +108,9 @@ The argument
 is not a valid descriptor.
 .TP
 .B ENOTSOCK
-The argument
+The file descriptor
 .I sockfd
-is not a socket.
+does not refer to a socket.
 .TP
 .B EOPNOTSUPP
 The socket is not of a type that supports the

man2/recv.2

@@ -479,7 +479,7 @@ and
 .BR accept (2)).
 .TP
 .B ENOTSOCK
-The argument
+The file descriptor
 .I sockfd
 does not refer to a socket.
 .SH CONFORMING TO

man2/send.2

@@ -399,9 +399,9 @@ No memory available.
 The socket is not connected, and no target has been given.
 .TP
 .B ENOTSOCK
-The argument
+The file descriptor
 .I sockfd
-is not a socket.
+does not refer to a socket.
 .TP
 .B EOPNOTSUPP
 Some bit in the

man2/shutdown.2

@@ -86,8 +86,9 @@ An invalid value was specified in
 The specified socket is not connected.
 .TP
 .B ENOTSOCK
+The file descriptor
 .I sockfd
-is a file, not a socket.
+does not refer to a socket.
 .SH CONFORMING TO
 POSIX.1-2001, POSIX.1-2008, 4.4BSD
 .RB ( shutdown ()