* header files for symbolic constants and data structures
** find /usr/include -type f -exec grep WTMP_FILE {} \; -print
    tells us that WTMP_FILE is defined in utmp.h
   find /usr/include -type f -exec grep _PATH_WTMP {} \; -print
    tells us what the real value is and where that is defined
* struct utmp
** remember, the "string" fields might not actually be strings
    use strn* to bound to the array length

* option handling
** getopt works for -f -e
    ":f:e"
** iterate over argv
** no need to support -username
** anything after -f is treated as a filename

* review details of the algorithm for dealing with records
** we used dumputmp to explore some wtmp files. no notes, just discussion.

* buffering strategy and -e option
** need to track the number of getrec calls and number of read calls
** be careful to think through how your choice of where to start the read
   impacts overall efficiency