Thursday, November 26, 2009

Long DNS Resolving time in Ubuntu 9.10

It all begins after the first update of a fresh ubuntu 9.10 install. Everytime I opened a browser and go any website, it takes 5-10 seconds for it to resolve the DNS. This applies to both Chrome and Firefox. I did tons of research on the internet. Lots of people concluded it is caused by the new DNS mechanism in Firefox 3.5. In this version, Firefox tend to use ipv6 to resolve DNS at first. Then after 3 failures, it will start to use ipv4. So people suggested to config firefox so that ipv6 is disabled. Also, some others suggested this is not enough, an update on the Grub to completely block ipv6 is necessary. I tried both, but neither of them solves the issue.

By "time dig www.google.ca", it still takes nearly 5 sec to "looking for host".

Then I read this:

http://www.unixmen.com/linux-tutorials/567-internet-connexion-is-very-slow-on-karmic-koala-solution-

By manually specifying DNS address (I got it from my router's config, do not use your router as the DNS server), the issue is solved.

Wednesday, November 25, 2009

100 Vim commands a programmer should know

From: http://www.catswhocode.com/blog/100-vim-commands-every-programmer-should-know

Search

/word Search “word” from top to bottom
?word Search “word” from bottom to top
/jo[ha]n Search “john” or “joan”
/\<> Search “the”, “theatre” or “then”
/the\> Search “the” or “breathe”
/\<> Search “the”
/\< ….\> Search all words of 4 letters
/\/ Search “fred” but not “alfred” or “frederick”
/fred\|joe Search “fred” or “joe”
/\<\d\d\d\d\> Search exactly 4 digits
/^\n\{3} Find 3 empty lines
:bufdo /searchstr/ Search in all open files

Replace

:%s/old/new/g Replace all occurences of “old” by “new” in file
:%s/old/new/gw Replace all occurences with confirmation
:2,35s/old/new/g Replace all occurences between lines 2 and 35
:5,$s/old/new/g Replace all occurences from line 5 to EOF
:%s/^/hello/g Replace the begining of each line by “hello”
:%s/$/Harry/g Replace the end of each line by “Harry”
:%s/onward/forward/gi Replace “onward” by “forward” , case unsensitive
:%s/ *$//g Delete all white spaces
:g/string/d Delete all lines containing “string”
:v/string/d Delete all lines containing which didn't contain “string”
:s/Bill/Steve/ Replace the first occurence of “Bill” by “Steve” in current line
:s/Bill/Steve/g Replace “Bill” by “Steve” in current line
:%s/Bill/Steve/g Replace “Bill” by “Steve” in all the file
:%s/\r//g Delete DOS carriage returns (^M)
:%s/\r/\r/g Transform DOS carriage returns in returns
:%s#<[^>]\+>##g Delete HTML tags but keeps text
:%s/^\(.*\)\n\1$/\1/ Delete lines which appears twice
Ctrl+a Increment number under the cursor
Ctrl+x Decrement number under cursor
ggVGg? Change text to Rot13

Case

Vu Lowercase line
VU Uppercase line
g~~ Invert case
vEU Switch word to uppercase
vE~ Modify word case
ggguG Set all text to lowercase
:set ignorecase Ignore case in searches
:set smartcase Ignore case in searches excepted if an uppercase letter is used
:%s/\<./\u&/g Sets first letter of each word to uppercase
:%s/\<./\l&/g Sets first letter of each word to lowercase
:%s/.*/\u& Sets first letter of each line to uppercase
:%s/.*/\l& Sets first letter of each line to lowercase

Read/Write files

:1,10 w outfile Saves lines 1 to 10 in outfile
:1,10 w >> outfile Appends lines 1 to 10 to outfile
:r infile Insert the content of infile
:23r infile Insert the content of infile under line 23

File explorer

:e . Open integrated file explorer
:Sex Split window and open integrated file explorer
:browse e Graphical file explorer
:ls List buffers
:cd .. Move to parent directory
:args List files
:args *.php Open file list
:grep expression *.php Returns a list of .php files contening expression
gf Open file name under cursor

Interact with Unix

:!pwd Execute the “pwd” unix command, then returns to Vi
!!pwd Execute the “pwd” unix command and insert output in file
:sh Temporary returns to Unix
$exit Retourns to Vi

Alignment

:%!fmt Align all lines
!}fmt Align all lines at the current position
5!!fmt Align the next 5 lines

Tabs

:tabnew Creates a new tab
gt Show next tab
:tabfirst Show first tab
:tablast Show last tab
:tabm n(position) Rearrange tabs
:tabdo %s/foo/bar/g Execute a command in all tabs
:tab ball Puts all open files in tabs

Window spliting

:e filename Edit filename in current window
:split filename Split the window and open filename
ctrl-w up arrow Puts cursor in top window
ctrl-w ctrl-w Puts cursor in next window
ctrl-w_ Maximise current window
ctrl-w= Gives the same size to all windows
10 ctrl-w+ Add 10 lines to current window
:vsplit file Split window vertically
:sview file Same as :split in readonly mode
:hide Close current window
:o nly Close all windows, excepted current
:b 2 Open #2 in this window

Auto-completion

Ctrl+n Ctrl+p (in insert mode) Complete word
Ctrl+x Ctrl+l Complete line
:set dictionary=dict Define dict as a dictionnary
Ctrl+x Ctrl+k Complete with dictionnary

Marks

mk Marks current position as k
‘k Moves cursor to mark k
d’k Delete all until mark k

Abbreviations

:ab mail mail@provider.org Define mail as abbreviation of mail@provider.org

Text indent

:set autoindent Turn on auto-indent
:set smartindent Turn on intelligent auto-indent
:set shiftwidth=4 Defines 4 spaces as indent size
ctrl-t, ctrl-d Indent/un-indent in insert mode
>> Indent
<< Un-indent

Syntax highlighting

:syntax on Turn on syntax highlighting
:syntax off Turn off syntax highlighting
:set syntax=perl Force syntax highlighting