write(2) [v7 man page]

WRITE(2)							System Calls Manual							  WRITE(2)

NAME

       write - write on a file

SYNOPSIS

       write(fildes, buffer, nbytes)
       char *buffer;

DESCRIPTION

       A file descriptor is a word returned from a successful open, creat, dup, or pipe(2) call.

       Buffer  is  the	address  of  nbytes  contiguous  bytes which are written on the output file.  The number of characters actually written is
       returned.  It should be regarded as an error if this is not the same as requested.

       Writes which are multiples of 512 characters long and begin on a 512-byte boundary in the file are more efficient than any others.

SEE ALSO

       creat(2), open(2), pipe(2)

DIAGNOSTICS

       Returns -1 on error: bad descriptor, buffer address, or count; physical I/O errors.

ASSEMBLER

       (write = 4.)
       (file descriptor in r0)
       sys write; buffer; nbytes
       (byte count in r0)

																	  WRITE(2)

WRITE(2)							System Calls Manual							  WRITE(2)

NAME

       write - write output

SYNOPSIS

       #include <sys/types.h>
       #include <unistd.h>

       ssize_t write(int d, const void *buf, size_t nbytes)

DESCRIPTION

       Write attempts to write nbytes of data to the object referenced by the descriptor d from the buffer pointed to by buf.

       On  objects  capable  of  seeking,  the	write starts at a position given by the pointer associated with d, see lseek(2).  Upon return from
       write, the pointer is incremented by the number of bytes actually written.

       Objects that are not capable of seeking always write from the current position.	The value of the pointer associated with such an object is
       undefined.

       When  using  non-blocking  I/O  on  objects  such  as  TCP/IP  channels	that are subject to flow control, write may write fewer bytes than
       requested; the return value must be noted, and the remainder of the operation should be retried when possible.

RETURN VALUE

       Upon successful completion the number of bytes actually written is returned.  Otherwise a -1 is returned and the global variable  errno	is
       set to indicate the error.

ERRORS

       Write will fail and the file pointer will remain unchanged if one or more of the following are true:

       [EBADF]	      D is not a valid descriptor open for writing.

       [EPIPE]	      An attempt is made to write to a pipe that is not open for reading by any process.

       [EPIPE]	      An attempt is made to write to a TCP channel that is not connected to a peer socket.

       [EFBIG]	      An attempt was made to write a file that exceeds the process's file size limit or the maximum file size.

       [EFAULT]       Part of the data to be written to the file points outside the process's allocated address space.

       [ENOSPC]       There is no free space remaining on the file system containing the file.

       [EIO]	      An I/O error occurred while reading from or writing to the file system.

       [EAGAIN]       The file was marked for non-blocking I/O, and no data could be written immediately.

SEE ALSO

       fcntl(2), lseek(2), open(2), pipe(2), read(2).

4th Berkeley Distribution					   May 14, 1986 							  WRITE(2)