open crontab -e in vi editor

EDITOR=vi;
export EDITOR

Now, crontab -e will open a vi editor for me. :-)

Runlevels in redhat linux

Generally, Red Hat Linux operates in runlevel 3 — full multi-user mode. The following runlevels are defined in Red Hat Linux:

• 0 — Halt
• 1 — Single-user mode
• 2 — Not used (user-definable)
• 3 — Full multi-user mode
• 4 — Not used (user-definable)
• 5 — Full multi-user mode (with an X-based login screen)
• 6 — Reboot

How to register an ActiveX control (.ocx) manually

You can use the Microsoft Register Server (Regsvr32.exe) to register a 32- bit .ocx file manually on a 32-bit operating system

Regsvr32 [/u] [/s] 

Note
  /u means Unregister the .ocx file.
  /s means Silent Mode (display no messages).

Ref http://support.microsoft.com/kb/146219