/etc/utmp /var/adm/wtmp

These files hold user and accounting information for commands such as who, write, and login. In Solaris 2.x, each of these files has been replaced with a pair of files: /etc/utmp has been replaced with /var/adm/utmp and /var/adm/utmpx, and /var/adm/wtmp with /var/adm/wtmp and /var/adm/wtmpx. When an application opens one of these files, it receives the concatenation of its two new counterparts.

Symbolic links to these files are no longer supported. This is, if an application creates a link to /etc/utmp or /var/adm/wtmp, and attempts to open the symbolic link, the open call fails.