debian man page for io_wantwrite

io_wantwrite(3) 					     Library Functions Manual						   io_wantwrite(3)

NAME
       io_wantwrite - signal that you want to write to a descriptor

SYNTAX
       #include <io.h>

       void io_wantwrite(int64 fd);

DESCRIPTION
       io_wantwrite tells the next io_wait() that you want to write to this descriptor.  Call io_dontwantwrite() again if you change your mind.

       The  next  time	you  call io_wait(), it will look whether this descriptor becomes writeable, too.  You can then use io_canwrite() to check
       whether the descriptor has become writable.

       You have to have called io_fd on the descriptor first (io_pipe and io_socketpair do this for you).  Waiting on descriptors only	works  for
       sockets, fifos and pipes.  It may also work on devices and TTYs, but that is platform dependent -- you should not rely on that.

SEE ALSO
       io_wait(3), io_canwrite(3), io_wantwrite(3), io_fd(3)

																   io_wantwrite(3)