.TH tee 2 2006-04-28 "Linux 2.6.17" "Linux Programmer's Manual"
.SH NAME
tee \- duplicating pipe content.
.SH SYNOPSIS
.B #include <sys/splice.h>

.B long tee(int fd_in, int fd_out, size_t bytes, unsigned int flags);

.SH DESCRIPTION
.BR tee ()
duplicates at most
.I bytes
of content from pipe
.I fd_in
to pipe
.IR fd_out .
.I flags
is a series of modifier flags, which share the name space with
.BR splice (2)
and
.BR vmsplice (2):

.TP 1.9i
.B SPLICE_F_MOVE
See
.BR splice (2)
.TP
.B SPLICE_F_NONBLOCK
Do not block on io.
.TP
.B SPLICE_F_MORE
More data will be coming in a subsequent splice.
.TP
.B SPLICE_F_GIFT
See
.BR vmsplice (2)

.PP
.BR tee ()
doesn't copy any data around, it simply references the input data and
links it to the output pipe.

.SH RETURN VALUE
Upon successful completion,
.BR tee ()
shall return the number of bytes that was duplicated between the input
and output. Otherwise, it shall return a value of -1 and
.I errno
shall be set to indicate an error.

.SH ERRORS
.TP 1.1i
.B EBADF
.I fd
either not valid, or none of the descriptors refer to a pipe.
.TP
.B EINVAL
Target file system doesn't support splicing, none of the descriptors refer
to a pipe or offset given for non-seekable device.

.SH SEE ALSO
.BR splice (2),
.BR vmsplice (2)

.SH AUTHORS
Jens Axboe <axboe@suse.de>