2.9BSD/usr/man/man8/ac.8

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.TH AC 8 
.SH NAME
ac \- login accounting
.SH SYNOPSIS
.B ac
[
.B \-w
wtmp ] [
.B \-p
] [
.B \-d
] [ people ] ...
.SH DESCRIPTION
.I Ac
produces a printout giving
connect time
for each user who has logged in
during the life of the current
.I wtmp
file.
A total is also produced.
Options are:
.TP
.B \-\^d
Causes a printout for each midnight to midnight period.
.TP
.B \-\^p
Print individual totals; without this option only totals are printed.
.TP
.B \-\^w
Use
.I wtmp
as an alternate accounting data file.
Any
.I people
will limit the printout to only the specified login names.  If
no
.I wtmp
file is given,
.I /usr/adm/wtmp
is used.
.PP
The accounting file,
.IR /usr/adm/wtmp ,
is maintained by
.IR init (8)
and
.IR login (1).
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 undisturbed it will
grow without bound, so periodically any information
desired should be collected and the file truncated.
.SH FILES
.ta 2i
/usr/adm/wtmp	default accounting file
.SH "SEE ALSO"
login(1), utmp(5), init(8)