1.1 Flags

All of the original ac’s options have been implemented, and a few have been added. Normally, when ac is invoked, the output looks like this:

        total 93867.14

where total is the number of hours of connect time for every entry in the wtmp file. The rest of the flags modify the output in one way or another.

-d

--daily-totals

Print totals for each day rather than just one big total at the end. The output looks like this:

Jul  3  total     1.17
Jul  4  total     2.10
Jul  5  total     8.23
Jul  6  total     2.10
Jul  7  total     0.30

-p

--individual-totals

Print time totals for each user in addition to the usual everything-lumped-into-one value. It looks like:

        bob       8.06
        goff      0.60
        maley     7.37
        root      0.12
        total    16.15

people

Print out the sum total of the connect time used by all of the users included in people. Note that people is a space separated list of valid user names; wildcards are not allowed.

-f filename

--file filename

Read from the file filename instead of the system’s wtmp file.

--complain

When the wtmp file has a problem (a time-warp, missing record, or whatever), print out an appropriate error.

--reboots

Reboot records are not written at the time of a reboot, but when the system restarts; therefore, it is impossible to know exactly when the reboot occurred. Users may have been logged into the system at the time of the reboot, and many ac’s automatically count the time between the login and the reboot record against the user (even though all of that time shouldn’t be, perhaps, if the system is down for a long time, for instance). If you want to count this time, include the flag. To make ac behave like the one that was distributed with your OS, include this flag.

--supplants

Sometimes a logout record is not written for a specific terminal, so the time that the last user accrued cannot be calculated. If you want to include the time from the user’s login to the next login on the terminal (though probably incorrect), include this flag. To make ac behave like the one that was distributed with your OS, include this flag.

--timewarps

Sometimes, entries in a wtmp file will suddenly jump back into the past without a clock change record occurring. It is impossible to know how long a user was logged in when this occurs. If you want to count the time between the login and the time warp against the user, include this flag. To make ac behave like the one that was distributed with your OS, include this flag.

--compatibility

This is shorthand for typing out the three above options.

-a

--all-days

If we’re printing daily totals, print a record for every day instead of skipping intervening days where there is no login activity. Without this flag, time accrued during those intervening days gets listed under the next day where there is login activity.

-y

--print-year

Print out the year when displaying dates.

--print-zeros

If a total for any category (save the grand total) is zero, print it. The default is to suppress printing.

--debug

Print verbose internal information.

--tw-leniency value

Set the time warp leniency value (in seconds). Records in wtmp files might be slightly out of order (most notably when two logins occur within a one-second period – the second one gets written first). By default, this value is set to 1 second. Some wtmp’s are really screwed up (Suns) and require a larger value here. If the program notices this problem, time is not assigned to users unless the --timewarps flag is used. See the Problems section for more information.

--tw-suspicious value

Set the time warp suspicious value (in seconds). If two records in the wtmp file are farther than this number of seconds apart, there is a problem with the wtmp file (or your machine hasn’t been used in a year). If the program notices this problem, time is not assigned to users unless the --timewarps flag is used.

-V

--version

Print ac’s version number.

-h

--help

Print ac’s usage string and default locations of system files to standard output.

1.2 Problems

For no fault of ac’s, if two logins occur at the same time (within a second of each other), each login process will try to write an entry to the wtmp file. With file system overhead, it is forseeable that the entries would get written in the wrong order. GNU ac automatically compensates for this, but some other acs may not... beware.

• The FTP Problem