Slow SATA Harddisk access?

Windows, Windows XP No Comments »

Very slow access is a symptom of XP having reverted to PIO access mode for the hard disk. To slove this open the registery and delete the all occurances of the below two registery keys.

  • MasterIdDataChecksum
  • SlaveIdDataChecksum 

These keys will be at the below locations:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\ Class\{4D36E96A-E325-11CE-BFC1-08002BE10318}\000x
The last four digits will be 0000, 0001, 0002, 0003, and so on.
  For better results search and delete.Now reboot your system. 

vi Editor Commands

Fedora, Linux, Mandrake, Redhat, Suse, Ubuntu No Comments »

General Startup
To use vi: vi filename
To exit vi and save changes: ZZ or :wq
To exit vi without saving changes: :q!
To enter vi command mode: [esc]
Counts
A number preceding any vi command tells vi to repeat
that command that many times.

Cursor Movement

h move left (backspace)

j move down

k move up

l move right (spacebar)

[return] move to the beginning of the next line

$ last column on the current line

0 move cursor to the first column on the
current line

^ move cursor to first nonblank column on the
current line

w move to the beginning of the next word or
punctuation mark

W move past the next space

b move to the beginning of the previous word
or punctuation mark

B move to the beginning of the previous word,
ignores punctuation

e end of next word or punctuation mark

E end of next word, ignoring punctuation

H move cursor to the top of the screen

M move cursor to the middle of the screen

L move cursor to the bottom of the screen

Screen Movement

G move to the last line in the file

xG move to line x

z+ move current line to top of screen

z move current line to the middle of screen

z- move current line to the bottom of screen

^F move forward one screen

^B move backward one line

^D move forward one half screen

^U move backward one half screen

^R redraw screen
( does not work with VT100 type terminals )

^L redraw screen
( does not work with Televideo terminals )

Inserting

r replace character under cursor with next
character typed

R keep replacing character until [esc] is hit

i insert before cursor

a append after cursor

A append at end of line

O open line above cursor and enter append mode

Deleting

x delete character under cursor

dd delete line under cursor

dw delete word under cursor

db delete word before cursor

Copying Code

yy (yank)’copies’ line which may then be put by
the p(put) command. Precede with a count for
multiple lines.

Put Command
brings back previous deletion or yank of lines,
words, or characters

P bring back before cursor

p bring back after cursor

Find Commands

? finds a word going backwards

/ finds a word going forwards

f finds a character on the line under the
cursor going forward

F finds a character on the line under the
cursor going backwards

t find a character on the current line going
forward and stop one character before it

T find a character on the current line going
backward and stop one character before it

; repeat last f, F, t, T

Miscellaneous Commands

. repeat last command

u undoes last command issued

U undoes all commands on one line

xp deletes first character and inserts after
second (swap)

J join current line with the next line

^G display current line number

% if at one parenthesis, will jump to its mate

mx mark current line with character x

‘x find line marked with character x

NOTE: Marks are internal and not written to the file.

Line Editor Mode
Any commands form the line editor ex can be issued
upon entering line mode.

To enter: type ‘:’

To exit: press[return] or [esc]

ex Commands
For a complete list consult the
UNIX Programmer’s Manual

READING FILES
copies (reads) filename after cursor in file
currently editing

:r filename

WRITE FILE

:w saves the current file without quitting

MOVING

:# move to line #

:$ move to last line of file

SHELL ESCAPE
executes ‘cmd’ as a shell command.

:!’cmd’

PostgreSQL database previleges

Linux, Postgres, Windows No Comments »

Privileges
When a database object is created, it is assigned an owner. The owner is the user that executed the creation statement. To change the owner of a table, index, sequence, or view, use the ALTER TABLE command. By default, only an owner (or a superuser) can do anything with the object. In order to allow other users to use it, privileges must be granted.

There are several different privileges: SELECT, INSERT, UPDATE, DELETE, RULE, REFERENCES, TRIGGER, CREATE, TEMPORARY, EXECUTE, USAGE, and ALL PRIVILEGES. For more information on the different types of privileges support by PostgreSQL, see the GRANT reference page. The right to modify or destroy an object is always the privilege of the owner only. To assign privileges, the GRANT command is used. So, if joe is an existing user, and accounts is an existing table, the privilege to update the table can be granted with

GRANT UPDATE ON accounts TO joe;

The user executing this command must be the owner of the table. To grant a privilege to a group, use

GRANT SELECT ON accounts TO GROUP staff;

The special “user” name PUBLIC can be used to grant a privilege to every user on the system. Writing ALL in place of a specific privilege specifies that all privileges will be granted.

To revoke a privilege, use the fittingly named REVOKE command:

REVOKE ALL ON accounts FROM PUBLIC;

The special privileges of the table owner (i.e., the right to do DROP, GRANT, REVOKE, etc) are always implicit in being the owner, and cannot be granted or revoked. But the table owner can choose to revoke his own ordinary privileges, for example to make a table read-only for himself as well as others.

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