rdchk() — unbundled ODT_SDS



     RDCHK(S)                  UNIX System V                  RDCHK(S)



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

     Syntax
          int rdchk(fdes);
          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 the
          process will not block when a read is attempted 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);

     See Also
          read(S)

     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.

     Notes
          This function must be linked with the linker option -lx.

                                             (printed 6/20/89)
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