Script to truncate wtmp files

Shell Programming and Scripting
1

Hi,

Does anyone have a script to truncate the wtmp file.

I want to move older entries in the wtmp to a new file and move it out of var/adm and shrink the size.

2

What OS are you on?

Linux uses logrotated to handle this, on AIX you would use fwtmp and if on Solaris you would most likely use logadm.

3

I am on AIX.
How to use fwtmp to rotate the logs?

4

Here you keep the last 500 and compress the rest and store in /scratch.

KEEP=500
DEST=/scratch

# Delete all but last $KEEP lines from wtmp
/usr/lib/acct/fwtmp < /var/adm/wtmp > $DEST/wtmp.out
tail -$KEEP $DEST/wtmp.out | /usr/lib/acct/fwtmp -ci > /var/adm/wtmp

# Keep everything except last $KEEP line in $DEST bzip2 date-stamped file
sed -e :a -e '$d;N;2,'$KEEP'ba' -e 'P;D'  $DEST/wtmp.out | bzip2> $DEST/wtmp_$(date +%Y%m%d).bz2
rm $DEST/wtmp.out

Note: if you don't have bzip2 installed, you could use compress instead

5

Thank you for the script.
let me test in one of my server.

---------- Post updated at 09:36 AM ---------- Previous update was at 08:51 AM ----------

It worked. Perfect script.
Thank you very much Chuber XL.