READ(2)                  HP Integral PC                   READ(2)
     READ(2)                  HP Integral PC                   READ(2)
     READ(2)                  HP Integral PC                   READ(2)
     READ(2)                  HP Integral PC                   READ(2)



     NAME
     NAME
     NAME
     NAME
          read - read from file

     SYNOPSIS
     SYNOPSIS
     SYNOPSIS
     SYNOPSIS
          int read (fildes, buf, nbyte)
          int fildes;
          char *buf;
          unsigned nbyte;

     DESCRIPTION
     DESCRIPTION
     DESCRIPTION
     DESCRIPTION
          Fildes is a file descriptor obtained from a creat , open ,
          dup , fcntl , or pipe system call.

          Read attempts to read nbyte bytes from the file associated
          with fildes into the buffer pointed to by buf .

          On devices capable of seeking, the read starts at a position
          in the file given by the file pointer associated with fildes
          .  Upon return from read , the file pointer is incremented
          by the number of bytes actually read.

          Devices that are incapable of seeking always read from the
          current position.  The value of a file pointer associated
          with such a file is undefined.

          Upon successful completion, read returns the number of bytes
          actually read and placed in the buffer; this number may be
          less than nbyte if the file is associated with a
          communication line (see ioctl (2) and tty (4)), or if the
          number of bytes left in the file is less than nbyte bytes.
          A value of 0 is returned when an end-of-file has been
          reached.

          When attempting to read from an empty pipe (or FIFO):

               If O_NDELAY is set, the read will return a 0.

               If O_NDELAY is clear, the read will block until data is
               written to the file or the file is no longer open for
               writing.

          When attempting to read a file associated with a tty that
          has no data currently available:

               If O_NDELAY is set, the read will return a 0.

               If O_NDELAY is clear, the read will block until data
               becomes available.

          Read will fail if one or more of the following are true:

               Fildes is not a valid file descriptor open for reading.



     Hewlett-Packard               - 1 -            (printed 12/11/84)






     READ(2)                  HP Integral PC                   READ(2)
     READ(2)                  HP Integral PC                   READ(2)
     READ(2)                  HP Integral PC                   READ(2)
     READ(2)                  HP Integral PC                   READ(2)



               [EBADF]

               Buf points outside the allocated address space.
               [EFAULT]

     RETURN VALUE
     RETURN VALUE
     RETURN VALUE
     RETURN VALUE
          Upon successful completion a non-negative integer is
          returned indicating the number of bytes actually read.
          Otherwise, a -1 is returned and errno is set to indicate the
          error.

     DIAGNOSTICS
     DIAGNOSTICS
     DIAGNOSTICS
     DIAGNOSTICS
          Information read from disc by the operating system is cached
          in memory for the purposes of speeding up access to
          information in files.  Consequently, not every read done of
          a file causes the system to go out to the physical medium to
          get data.  If this becomes necessary, one should do a sync
          before the read is executed.

     SEE ALSO
     SEE ALSO
     SEE ALSO
     SEE ALSO
          creat(2), dup(2), fcntl(2), ioctl(2), open(2), pipe(2),
          tty(4).

































     Hewlett-Packard               - 2 -            (printed 12/11/84)