/ sysadmin commands / Ac - Connect Time Accounting

ac - connect time accounting
ac [-dp] [-t tty] [-w wtmp] [users ...]
If the file /var/log/utx.log exists, a record of individual login and logout times are written to it by login and init , respectively. The ac utility examines these records and writes the accumulated connect time (in hours) for all logins to the standard output.

The options are as follows:
Display the connect times in 24 hour chunks.
Print individual users' totals.
-t tty
Only do accounting logins on certain ttys. The tty specification can start with '!' to indicate not this tty and end with '*' to indicate all similarly named ttys. Multiple -t flags may be specified.
-w wtmp
Read connect time data from wtmp instead of the default file, /var/log/utx.log.
users ...
Display totals for the given individuals only.

If no arguments are given, ac displays the total connect time for all accounts with login sessions recorded in utx.log.

The default utx.log file will increase without bound unless it is truncated. It is normally truncated by the daily scripts run by cron , which rename and rotate the utx.log files, keeping a week's worth of data on hand. No login or connect time accounting is performed if /var/log/utx.log does not exist.
connect time accounting file
The ac utility exits 0 on success, and >0 if an error occurs.
Allow times recorded in modems to be charged out at a different rate than other:

ac -p -t "ttyd*" > modems 
ac -p -t "!ttyd*" > other
login , getutxent , init , sa
accton - enable/disable system accounting
aa-status - display various information about the current AppArmor policy.