How to truncate /var/adm/wtmp in AIX

/var/adm/wtmp contains login and logoff information in reverse chronological order.

The last command can be used to view the contents of wtmp.

An example of the output of last is shown below.

$ last
oracle    pts/2        200.254.1.207         Jun 29 15:36 - 15:44  (00:08)
oracle    pts/2        192.253.1.20          Jun 29 15:34 - 15:35  (00:01)
oracle    pts/2        192.252.1.20          Jun 29 15:32 - 15:34  (00:02)
oracle    pts/2        192.252.1.20          Jun 29 15:27 - 15:31  (00:04)
oracle    pts/0        192.252.1.14          Jun 29 15:16 - 18:08  (02:52)
root      pts/1        168.29.10.7           Jun 29 15:03 - 00:55  (09:51)
oracle    pts/0        211.251.1.14          Jun 29 14:50 - 15:15  (00:25)
oracle    pts/2        211.252.1.14          Jun 28 23:49 - 23:49  (00:00)
oracle    pts/2        211.252.1.14          Jun 28 23:48 - 23:48  (00:00)
oracle    pts/3        211.253.1.14          Jun 28 23:48 - 00:06  (00:18)
oracle    pts/2        211.251.1.14          Jun 28 23:46 - 23:48  (00:01)
oracle    pts/0        211.252.1.14          Jun 28 23:44 - 00:05  (00:20)
root      pts/0        176.29.10.7           Jun 28 23:00 - 23:01  (00:00)
root      pts/0        176.29.10.7           Jun 28 22:57 - 23:00  (00:02)
root      pts/0        176.29.10.7           Jun 28 21:44 - 22:55  (01:10)
root      pts/0        176.29.10.7           Jun 28 21:43 - 21:43  (00:00)
root      pts/0        176.29.10.7           Jun 28 21:41 - 21:41  (00:00)
oracle    pts/1        212.252.1.14          Jun 28 17:18 - 00:07  (06:48)

wtmp will need to be truncated periodically to prevent it from getting too big.

To do so use the fwtmp command as shown below.

/usr/lib/acct/fwtmp < /var/adm/wtmp > /tmp/wtmp.out
tail -500 /tmp/wtmp.out > /tmp/wtmp.small
/usr/lib/acct/fwtmp -ci < /tmp/wtmp.small > /var/adm/wtmp
rm /tmp/wtmp.out
rm /tmp/wtmp.small

Emre Özkan About Emre Özkan

I live in Istanbul/TURKEY and working with Anadolubank.,I am Unix & Backup & Storage Admin in this company. My responsibilities are IBM Power Hardware(E850,P780,P770, etc.),IBM AIX,Tivoli Storage Manager,IBM Tape Libraries,Hitachi VSP and IBM DS8100 Storage.

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes:

<a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>