rdchk(2)       UNIX System V(Application Compatibility Package)        rdchk(2)


NAME
      rdchk - check 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 (for example, 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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