man telinit reveals that runlevel "1" is single user mode and "S" is also single user mode but it does not shut down the various services first. Of course on first boot there are no services running so I would imagine there is no real difference between the two. "single" is presumably an alias for either "1" or "S" but my quick search doesnt throw anything up. As for the other runlevels (1-6) /etc/inittab describes the general purpose of them. Hope thats the info you were looking for. <div class="gmail_quote">2008/11/11 G.Wolfe Woodbury <<a href="mailto:ggw@wolves.durham.nc.us">ggw@wolves.durham.nc.us</a>> <blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> GRUB command line parameter "S1" used to bring on single user mode (according to my reporter) but things have changed (probably in the kernel) so that "single" is required to get things right. Me, I always used "S" or "single" from the first introduction of LILO and GRUB, so this is a little confused sounding to me. Can someone explain the details of the "S", "1", "3", "5" and "single" kernel parameters behaviour? AIUI, they are passed to "init" to set the initial state of the system, and "single" is a synonym for "S" and that "S" and "1" are equivalent. TIA -- Wolfe -- fedora-test-list mailing list <a href="mailto:fedora-test-list@redhat.com">fedora-test-list@redhat.com</a> To unsubscribe: <a href="https://www.redhat.com/mailman/listinfo/fedora-test-list" target="_blank">https://www.redhat.com/mailman/listinfo/fedora-test-list</a> </blockquote></div>