send.2 (2010 09)

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send(2) send(2)

its peer.

[ENOTSOCK] s is a valid ﬁle descriptor, but it is not a socket.

[EOPNOTSUPP] The

MSG_OOB ﬂag was speciﬁed; it is not supported for AF_UNIX or

AF_VME_LINK sockets.

[EPIPE] and

SIGPIPE signal

An attempt was made to send on a socket that was connected, but the connec-

tion has been shut down either by the remote peer or by this side of the con-

nection. Note that the default action for SIGPIPE

, unless the process has

established a signal handler for this signal, is to terminate the process.

[EWOULDBLOCK] Nonblocking I/O is enabled using

ioctl() FIOSNBIO request and the

requested operation would block.

DEPENDENCIES

UDP messages are fragmented at the IP level into Maximum Transmission Unit (MTU) sized pieces; MTU

varies for different link types. These pieces, called IP fragments, can be transmitted, but IP does not

guarantee delivery. Sending large messages may cause too many fragments and overrun a receiver’s abil-

ity to receive them. If this happens the complete message cannot be reassembled. This affects the

apparent reliability and throughput of the network as viewed by the end user.

The default and maximum buffer sizes are protocol-speciﬁc. Refer to the appropriate entries in Sections

7F and 7P for details. The buffer size can be set by calling

setsockopt() with

SO_SNDBUF.

OBSOLESCENCE

Currently, the

socklen_t and size_t types are the same size. This is compatible with the UNIX 95

and UNIX 03 proﬁles. However, in a future release, socklen_t might be a different size. In that case,

the size of the msghdr and cmsghdr structures and the relative position of their members will be

different, which might affect application behavior. Applications that use socklen_t now, where

appropriate, will avoid such migration problems. On the other hand, applications that need to be port-

able to the UNIX 95 proﬁle should follow the X/Open speciﬁcation (see xopen_networking(7)).

WARNINGS

Linking binary objects compiled to X/Open Sockets speciﬁcation and binary objects compiled to HP-UX

BSD Sockets speciﬁcation to the same executable may result in unexpected behavior, including applica-

tion abnormal termination and unexpected socket errors. See xopen_networking(7) for details and

remedy.

FUTURE DIRECTION

Currently, the default behavior is the HP-UX BSD Sockets; however, it might be changed to X/Open

Sockets in a future release. At that time, any HP-UX BSD Sockets behavior that is incompatible with

X/Open Sockets might be obsoleted. Applications that conform to the X/Open speciﬁcation now will

avoid migration problems (see xopen_networking(7)).

AUTHOR

send(), sendmsg(), and sendto() were developed by HP and the University of California, Berke-

ley.

The

MSG_EOF feature is an HP-speciﬁc extension to the socket API.