Slogin is a login program to be used in single-user mode. It prompts the user:

root password (or ^D to log in as a user):

and waits for input.

If the user supplies the root password, slogin immediately initiates a root login session. Otherwise, if the user presses Control-D, the program prompts for user name and password and initiates a non-superuser session, provided that the supplied credentials are correct.

In both cases slogin does not try to write any files, in particular, it does not modify /var/log/utmp and /var/log/wtmp. This makes it useful in start-up scripts, when the root maintenance is necessary, escpecially when the partition containing these files is not mounted (e.g. fsck failed).