Troubleshooting Booting Problems

If a system fails to start correctly in multiuser mode, it s likely that one of the scripts being run in /etc/rc2.d is the cause. In order to prevent the system from going multiuser, it is possible to boot directly into single- user mode from the ok prompt:

 ok boot s ... INIT: SINGLE USER MODE Type Ctrl-d to proceed with normal startup, (or give root password for system maintenance): 

At this point, the root password can be entered, and the user will be given a root shell. However, not all file systems will be mounted, although individual scripts can then be checked individually for misbehaving applications.

If the system will not boot into single-user mode, the solution is more complicated because the default boot device cannot be used. For example, if an invalid entry has been made in the /etc/passwd file for the root user, the system will not boot into single- or multiuser mode. To recover the installed system, the host needs to be booted from the installation CD-ROM into single-user mode. At this point, the default root file system can be mounted on a separate mount point, the /etc/passwd file edited, and the system rebooted with the default boot device. This sequence of steps is shown next , assuming that /etc is located on /dev/dsk/c0t0d0s1 :

 ok boot cdrom ... INIT: SINGLE USER MODE Type Ctrl-d to proceed with normal startup, (or give root password for system maintenance): # mkdir /temp # mount /dev/dsk/c0t0d0s1 /temp # vi /temp/etc/passwd # sync; init 6