Frequently used commands in Linux

How to set the date or time to Linux:
Syntax: date MMDDhhmmYYYY.ss, where MM – month, DD – day, hh – hours, mm – minutes, YYYY – year, ss – seconds.
# Date 101215442012.00

(October 12, 2012. 15:44:00)

How to import a public key repository manually:
# Rpm –import PUBKEY …

How to make the file executable:
# Chmod + x file.sh