Write data to a file or a stream.
Writes data and returns the number of bytes that were
actually written. It can be less than the size of the given data if
some data was written successfully and then something went
wrong, or
nonblocking mode is used and not all data could be written
without blocking.
-1 is returned if something went wrong and no bytes were written.
If only some data was written due to an error and that error
persists, then a later call to write() will fail and return -1.
If everything went fine, a call to errno() directly afterwards
will return zero.
If data is an array of strings, they will be written sequence.
If more than one argument is given, sprintf() will be used to
format them using format . If format is an array, the strings
in it are concatenated and the result is used as format string.