tcpdump : capturing data

capture all traffic on port 80 for a specific machine

sudo tcpdump -A -s 0 -i eth0 dst or src host and port 80


Reference : http://code.google.com/support/bin/answer.py?answer=71567&topic=12022

Vim Movements - Some Common , Some Not so much

ESC + H Moves to the line at the top of the screen.
ESC + M Moves to the line in the middle of the screen.
ESC + L Moves to the line at the bottom of the screen.


[Ctrl-F] Move forwards one page.
[Ctrl-B] Move backwards one page.
[Ctrl-D] Move forwards by half a page.
[Ctrl-U] Move backwards by half a page.
[Ctrl-E] Display one more line at the bottom of the screen.
[Ctrl-Y] Display one more line at the top of the screen.

Reference : http://en.wikibooks.org/wiki/Learning_the_vi_editor/vi_Reference#Movement

Old Firefox Versions

http://releases.mozilla.org/pub/mozilla.org/firefox/releases/http://releases.mozilla.org/pub/mozilla.org/firefox/releases/

nmap - portscan

scan all the ports in a given range on a specific machine

nmap -p1-10000 127.0.0.1

The above command will scan host 127.0.0.1(localhost) to see if any of the ports from range 1 to 10000 is up.

Oracle - Enabling Parallelism

If your database server is running on multiple processor system. You can make all your processors conspire to run a query. You might want to do this when the query is known to take a long time and there is no way it would return in sane time. At the same time, be careful to run this on production systems as it may hamper performance of the database.

select /*+ parallel(x 4) */ count(1)
from huge_table
where huge_table.x = 'somevalue'

vim : ignoring white spaces in vimdiff

In your .vimrc file :
set diffopt+=iwhite


http://vim.wikia.com/wiki/Ignore_white_space_in_vimdiff

Appending to a register in vim

For example, you want to collect a sequence of lines into the a register. Yank the first line with:

"aY

Now move to the second line, and type:

"AY

Repeat this command for all lines. The a register now contains all those lines, in the order you yanked them.



Reference : Vim manual