rdchk(2)               (XENIX Compatibility Package)               rdchk(2)


   NAME
         rdchk - checks to see if there is data to be read

   SYNOPSIS
         cc [flag ...] file ... -lx
         rdchk(int fdes);

   DESCRIPTION
         rdchk checks to see if a process will block if it attempts to read
         the file designated by fdes.  rdchk returns 1 if there is data to be
         read or if it is the end of the file (EOF).  In this context, the
         proper sequence of calls using rdchk is:
               if(rdchk(fildes) > 0)
                   read(fildes, buffer, nbytes);

   DIAGNOSTICS
         rdchk returns -1 if an error occurs (e.g., EBADF), 0 if the process
         will block if it issues a read and 1 if it is okay to read.  EBADF is
         returned if a rdchk is done on a semaphore file or if the file
         specified doesn't exist.

   SEE ALSO
         read(2)






























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