ac - login accounting
ac [ -w wtmp ] [ -p ] [ -d ] [ people ] ...
Ac produces a printout giving connect time for each user who has logged
in during the life of the current wtmp file. A total is also produced.
-w is used to specify an alternate wtmp file. -p prints individual
totals; without this option, only totals are printed. -d causes a
printout for each midnight to midnight period. Any people will limit
the printout to only the specified login names. If no wtmp file is
given, /usr/adm/wtmp is used.
The accounting file /usr/adm/wtmp is maintained by init and login.
Neither of these programs creates the file, so if it does not exist no
connect-time accounting is done. To start accounting, it should be
created with length 0. On the other hand if the file is left undis-
turbed it will grow without bound, so periodically any information
desired should be collected and the file truncated.
init(8), login(1), utmp(5).