Impacts of emptying /var/adm/wtmp file ?

In our operating procedures, if a workstation has a space problem in the /var filesystem, one of the most frequent case we were told is the size of the /var/adm/wtmp file.

Someone once told me it is dangerous to do this. Is it ?

I cannot say for certain that whomever wrote that procedure is a qualified sys admin.

I definitely wouldn't delete that file, but reducing it is OK else it'll fill up /var

candlejack is correct. Do not delete the file, because processes are accessing it. instead reduce it to zero length by issuing

cat /dev/null > /var/adm/wtmp

The difference is that this way the file will keep its inode and hence alle the processes accessing it will still find the file where they look for it.

If you delete the file and it is created anew it would most probably get a different inode, which is a potential hazard.

I hope this helps.

bakunin