free online courses

http://www.udacity.com/  <- cs classes
http://coursera.org/

http://www.khanacademy.org/
http://www.khanacademy.org/#biology
http://www.khanacademy.org/#computer-science
UnCollege.org has a nice collection of online resources, including a lot of computer science resources: http://www.uncollege.org/resources.

- MIT Open Course Ware: http://ocw.mit.edu/courses/#electrical-engineering-and-computer-science
- Google Code University: http://code.google.com/edu/
- Stanford's Education Everywhere: http://see.stanford.edu/see/courses.aspx

using "screen" command to handle multiple sessions

from http://www.cyberciti.biz/tips/linux-screen-command-howto.html


$ screen -S 1
CTRL+a, c            -- create another screen window
CTRL+a, n            -- switch to next screen window I've got open

• 
  To list all windows use the command CTRL+a followed by " key (first hit CTRL+a, releases both keys and press " ).
• To switch to window by number use the command CTRL+a followed by ' (first hit CTRL+a, releases both keys and press ' it will prompt for window number).

Common screen commands

screen command	Task
Ctrl+a c	Create new window
Ctrl+a k	Kill the current window / session
Ctrl+a w	List all windows
Ctrl+a 0-9	Go to a window numbered 0 9, use Ctrl+a w to see number
Ctrl+a Ctrl+a	Toggle / switch between the current and previous window
Ctrl+a S	Split terminal horizontally into regions and press Ctrl+a c to create new window there
Ctrl+a :resize	Resize region
Ctrl+a :fit	Fit screen size to new terminal size. You can also hit Ctrl+a F for the the same task
Ctrl+a :remove	Remove / delete region. You can also hit Ctrl+a X for the same taks
Ctrl+a tab	Move to next region
Ctrl+a D (Shift-d)	Power detach and logout
Ctrl+a d	Detach but keep shell window open
Ctrl-a Ctrl-\	Quit screen
Ctrl-a ?	Display help screen i.e. display a list of commands

Suggested readings:

See screen command man page for further details:
man screen

awk

specify tab-delimited columns
awk -F'\t' '{ print $1}' file

print column $13 and column $10 where $13 matches "MY"
awk -F"\t" '$13 ~ /MY/ {print $13"\t"$10}' | less

awk -F"\t" '$7 == "restaurant" ' japan.osm.poi  > restaurants


awk '{ print \$1} ' file,   print 1st column, escape $ when in perl system command



not really sure what this does.....

awk -F "\"*,\"*" '{print $3"\t"$5}' jigyosyo.csv

iconv and recode to change file encoding

List all the encoding codes:

iconv --list

iconv --from-code LATIN1 --to-code UTF-8 --output adoos.com.my.categories.zlm-MYS.UTF.txt adoos.com.my.categories.zlm-MYS.LATIN1.txt

recode ....

windows 1252 encoding

CP1252 is windows encoding

em dash is a measurement of font size that is often double encoded?
to find it do:
zcat file | grep -P '\xc2\x96'

91,92,93,94 are also other troublesome windows chars