write

Writes a specified number of bytes from a buffer to a file.

Format 

#include  <unistd.h>

ssize_t write  (int file_desc, void *buffer,
               size_t nbytes); (ISO POSIX-1)

int write  (int file_desc, void *buffer,
           int nbytes); (Compatability)

Arguments

file_desc
A file descriptor that refers to a file currently opened for writing or updating.
buffer
The address of contiguous storage from which the output data is taken.
nbytes
The maximum number of bytes involved in the write operation.

Description

If the write is to an RMS record file and the buffer contains embedded new-line characters, more than one record may be written to the file. Even if there are no embedded new-line characters, if nbytes is greater than the maximum record size for the file, more than one record will be written to the file. The write function always generates at least one record.

If the write is to a mailbox and the third argument, nbytes, specifies a length of 0, an end-of-file message is written to the mailbox. This occurs for mailboxes created by the application using SYS$CREMBX, but not for mailboxes created to implement POSIX pipes. For more information, see Chapter 5.

Return Values
x  The number of bytes written. 
-1  Indicates errors, including undefined file descriptors, illegal buffer addresses, and physical I/O errors. 

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