Linux commands
[1] lsof -i :<port_number> : To find out who is listening to the specified port
jestinjoy@jestin:~$ lsof -i :80
COMMAND PID USER FD TYPE DEVICE SIZE NODE NAME
firefox-b 3463 jestinjoy 21u IPv4 22204 TCP 192.168.1.3:57779->maa03s01-in-f104.1e100.net:www (ESTABLISHED)
firefox-b 3463 jestinjoy 65u IPv4 22191 TCP 192.168.1.3:60551->maa03s01-in-f100.1e100.net:www (ESTABLISHED)
firefox-b 3463 jestinjoy 66u IPv4 22246 TCP 192.168.1.3:58349->nuq04s01-in-f113.1e100.net:www (ESTABLISHED)
firefox-b 3463 jestinjoy 77u IPv4 22713 TCP 192.168.1.3:48887->maa03s01-in-f95.1e100.net:www (ESTABLISHED)
[2] finger @kernel.org : Gives information about current kernel
jestinjoy@jestin:~$ finger @kernel.org
[kernel.org]
The latest linux-next version of the Linux kernel is: next-20110506
The latest snapshot 2.6 version of the Linux kernel is: 2.6.39-rc6-git6
The latest mainline 2.6 version of the Linux kernel is: 2.6.39-rc6
The latest stable 2.6.38 version of the Linux kernel is: 2.6.38.5
The latest stable 2.6.37 version of the Linux kernel is: 2.6.37.6
The latest stable 2.6.36 version of the Linux kernel is: 2.6.36.4
The latest longterm 2.6.35 version of the Linux kernel is: 2.6.35.13
The latest stable 2.6.35 version of the Linux kernel is: 2.6.35.9
The latest longterm 2.6.34 version of the Linux kernel is: 2.6.34.9
The latest longterm 2.6.33 version of the Linux kernel is: 2.6.33.12
The latest longterm 2.6.32 version of the Linux kernel is: 2.6.32.39
The latest stable 2.6.32 version of the Linux kernel is: 2.6.32.28
The latest longterm 2.6.27 version of the Linux kernel is: 2.6.27.59
The latest stable 2.6.27 version of the Linux kernel is: 2.6.27.57
The latest stable 2.4.37 version of the Linux kernel is: 2.4.37.11
[3] date -s "21 JUL 2011 19:13:00" : Set date and time from command line
# date -s "21 JUL 2011 19:13:00"
Thu Jul 21 19:13:00 IST 2011
[4] getconf PAGESIZE : Gives the page size value
# getconf PAGESIZE
4096