CSCI-E28                    Lecture 2                     Outline
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          Topics:   Files, System Files, the Manual, Buffering

          Approach: Write our own versions of Unix programs

          Featured Commands:
                    who
                    cp
                    tail

          Main Ideas:
                    i/o redirection, pipes
                    standard directories/files
                    the manual tells all
                    open, read, write, close
                    unix time
                    `expensive' operations
                    buffered input/output


          Applications:
                    who0 : writing a system utility
                       the manual, the header files

                    who1 : reading and displaying data
                       the utmp file
                       open(), read()

                    who2 : displaying dates and times
                       localtime(), strftime()

                    cp : writing data, creating files
                      creat(), open()
                      write()
                      effect of buffer size:
                        efficiency, system calls, buffering

                    who3 : making who more efficient
                      more buffering

                    kernel buffering
                      speedier disk access

                    tail
                      lseek()
                      what it does
                      how it does it