table of contents
- wheezy 3.44-1
- jessie 3.74-1
- jessie-backports 4.10-2~bpo8+1
- testing 4.10-2
- unstable 4.10-2
|SENDFILE(2)||Linux Programmer's Manual||SENDFILE(2)|
NAME¶sendfile - transfer data between file descriptors
DESCRIPTION¶sendfile() copies data between one file descriptor and another. Because this copying is done within the kernel, sendfile() is more efficient than the combination of read(2) and write(2), which would require transferring data to and from user space.
RETURN VALUE¶If the transfer was successful, the number of bytes written to out_fd is returned. On error, -1 is returned, and errno is set appropriately.
- Nonblocking I/O has been selected using O_NONBLOCK and the write would block.
- The input file was not opened for reading or the output file was not opened for writing.
- Bad address.
- Descriptor is not valid or locked, or an mmap(2)-like operation is not available for in_fd.
- Unspecified error while reading from in_fd.
- Insufficient memory to read from in_fd.
VERSIONS¶sendfile() is a new feature in Linux 2.2. The include file <sys/sendfile.h> is present since glibc 2.1.
CONFORMING TO¶Not specified in POSIX.1-2001, or other standards.
NOTES¶If you plan to use sendfile() for sending files to a TCP socket, but need to send some header data in front of the file contents, you will find it useful to employ the TCP_CORK option, described in tcp(7), to minimize the number of packets and to tune performance.
SEE ALSO¶mmap(2), open(2), socket(2), splice(2)
COLOPHON¶This page is part of release 3.44 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.