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RedHat 9 (Linux i386) - man page for write (redhat section 2)

WRITE(2)			    Linux Programmer's Manual				 WRITE(2)

NAME
       write - write to a file descriptor

SYNOPSIS
       #include <unistd.h>

       ssize_t write(int fd, const void *buf, size_t count);

DESCRIPTION
       write  writes  up to count bytes to the file referenced by the file descriptor fd from the
       buffer starting at buf.	POSIX requires that a read() which can be proved to occur after a
       write()	has returned returns the new data.  Note that not all file systems are POSIX con-
       forming.

RETURN VALUE
       On success, the number of bytes written are returned (zero indicates nothing was written).
       On  error,  -1 is returned, and errno is set appropriately.  If count is zero and the file
       descriptor refers to a regular file, 0 will be returned without causing any other  effect.
       For a special file, the results are not portable.

ERRORS
       EBADF  fd is not a valid file descriptor or is not open for writing.

       EINVAL fd is attached to an object which is unsuitable for writing.

       EFAULT buf is outside your accessible address space.

       EFBIG  An attempt was made to write a file that exceeds the implementation-defined maximum
	      file size or the process' file size limit, or to write at a position past than  the
	      maximum allowed offset.

       EPIPE  fd is connected to a pipe or socket whose reading end is closed.	When this happens
	      the writing process will also receive a SIGPIPE signal.  (Thus,  the  write  return
	      value is seen only if the program catches, blocks or ignores this signal.)

       EAGAIN Non-blocking I/O has been selected using O_NONBLOCK and the write would block.

       EINTR  The call was interrupted by a signal before any data was written.

       ENOSPC The device containing the file referred to by fd has no room for the data.

       EIO    A low-level I/O error occurred while modifying the inode.

       Other errors may occur, depending on the object connected to fd.

CONFORMING TO
       SVr4,  SVID,  POSIX,  X/OPEN, 4.3BSD.  SVr4 documents additional error conditions EDEADLK,
       ENOLCK, ENOLNK, ENOSR, ENXIO, or ERANGE.  Under SVr4 a write may be interrupted and return
       EINTR at any point, not just before any data is written.

NOTES
       A successful return from write does not make any guarantee that data has been committed to
       disk.  In fact, on some buggy implementations, it does not even guarantee that  space  has
       successfully  been  reserved  for  the  data.  The only way to be sure is to call fsync(2)
       after you are done writing all your data.

SEE ALSO
       close(2), fcntl(2), fsync(2), ioctl(2), lseek(2), open(2), read(2), select(2),  fwrite(3),
       writev(3)

Linux 2.0.32				    2001-12-13					 WRITE(2)


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