Ask Ubuntu General Room

Marco Ceppi

12:58 AM

ajmitch

1:11 AM

That doesn't look right...

It shows up as a proper link for me

Marco Ceppi

I didn't think so

@ajmitch yeah - it only happens in one part of the site

ajmitch

1:25 AM

@JorgeCastro nice to read about you being an ubuntu developer on LWN :)

lwn.net/Articles/427883 for those LWN subscribers (part of ubuntu membership)

George Edison

2:17 AM

No, it's displaying fine for me.

TheX

muahaha

George Edison

...and that is a...?

NASA's replacement for the Space Shuttle?

TheX

yes to replace the Space shuttles

they should hire me...

actually it was my after school project, model rocket :-D

George Edison

Oh, cool.

TheX

now all i have to do is stop at the nuclear waste dump tomorrow and pick up some uranium :-D

ajmitch

3:00 AM

@JorgeCastro is fast on editing today, questions barely have time to show up before they're edited :)

Jorge Castro

going to bed now!

ajmitch

heh, night

Kaustubh P

3:28 AM

good morning!

George Edison

3:59 AM

@TheX: No, plutonium... much more radioactive :)

TheX

@GeorgeEdison ever sense I said that I keep waiting for homeland security to knock on my door

George Edison

...oh?

TheX

4:16 AM

the whole nuclear weapon thing @GeorgeEdison

George Edison

5:37 AM

You have nuclear weapons?!?!

^---- Centrifuge for uranium enrichment.

P.S. Please use it for peaceful purposes.

Thank you. That is all.

Kaustubh P

lmao!

htorque

11:59 AM

5

Q: Removing folder named ~

This is the output of ls -l ls -l total 53484 drwxr-xr-x 3 root root 4096 2011-02-10 05:59 ~ -rw-r--r-- 1 root root 54313810 2011-02-13 05:09 jobs.jar -rw-r--r-- 1 root root 384035 2011-02-15 05:33 jobsLog.out I cant do rm -rf ~ because that will remove my home directory. What should ...

bash rm

hehe, i actually did that rm -rf ~ once... it only ran for a split second before the ctrl+c, but home was already toast

Stefano Palazzo

I wonder what's wrong with my answer on this one

htorque

looks right to me :-)

Stefano Palazzo

Maybe it's because I edited it straight away, so for a while it looked like i was a minute behind Ward

Stefano Palazzo

12:16 PM

@htorque you know about algorithms, right?

htorque

a bit :-)

Stefano Palazzo

So, I've been trying to serialise a binary search tree onto an array, and the Length of the array is - in a worst case - 2^n

I'm doing something wrong, aren't I?

my left and right nodes are 2*n+1 and 2*n+2

htorque

oooh, wait... that data structures thingy is years back :P

yeah, left right 2n+1 2n+2 is good

hm, shouldn't the array be of length... well, n?

Stefano Palazzo

not if the tree isn't balanced

so, I'm adding 0..15, and the 15 ends up at index 65534 (2^n-1)

htorque

what are you storing in the array? the (sorted) nodes?

Stefano Palazzo

12:23 PM

it's hanging all the way to the left

this is how I store:

I'm looking at the root node, if it's Null, I make it the value, else, if the value is <= the root nodes value, I go to the left (2n+1) of the current node and make that the root node (and right if it's >), repeat until the value is stored somewhere

htorque

n = number of parent node, right?

not size of the tree

so left child of node 1 is 2*1+1=3, right child is 2*1+2=4, aso.

Stefano Palazzo

right, n is the current index pointer

htorque

ah, now i got your problem... cold caffeine turkey is no fun!

Stefano Palazzo

so, this is my worst case, all of the entries end up on the right of the node last visited

htorque

make it an avl tree then :P

Stefano Palazzo

12:35 PM

I will, but I'd like to be sure that this is a problem with binary trees and not a catastrophic mistake on my part (:

htorque

oh no, that's how inserting into bin trees work - except, i don't think two nodes with the same value are allowed (you used <= above)

Stefano Palazzo

yeah, that's just to keep the implementation simple for now

I wouldn't bother, normally. But I only learned the recursive algorithms at Uni, and I'd like to do everything iteratively, so I'm going through all of the data structures once again

well thanks a lot, quite helpful :)

htorque

no not really helpful :P all those easy stuff is gone from my memory - i only know where to look if i'd really need it one day :D

worst case array size should be... 2^depth-1 (so 2^(n-1)-1)

insert 1, 2, 3, you'd have 7 nodes in a full bin tree, 2^2-1

Stefano Palazzo

It's a bit frustrating. I've implemented one kind of tree that's pretty much perfect. Insertion, deletion and search is O(log n), and space is O(n), but it's still thousands of times slower than just sorting a python list at every step :P

htorque

:D

Stefano Palazzo

12:42 PM

I'm still waiting for the DHL guy to deliver "the C programming language" (:

htorque

hehe, DHL... good luck

wasn't there something like a heap tree?

Stefano Palazzo

theres a Heap

htorque

Binary heap

A binary heap is a heap data structure created using a binary tree. It can be seen as a binary tree with two additional constraints: *The shape property: the tree is a complete binary tree; that is, all levels of the tree, except possibly the last one (deepest) are fully filled, and, if the last level of the tree is not complete, the nodes of that level are filled from left to right. *The heap property: each node is greater than or equal to each of its children according to some comparison predicate which is fixed for the entire data structure. "Greater than or equal to" means accordi...

damn... if i had more time i'd look through my lecture notes - that stuff was quite interesting. so many ways to screw up implementations. :D

Stefano Palazzo

That's basically what I'm doing, except a binary heap can be implemented in as a reasonably sized array, so that looks like the solution to the problem of "implementing a binary search tree as an array is stupid" (:

the difference is that you "heapify" at every insertion, rather than always having all the nodes at the "correct" position. But what's the use if you can just use pointers to the left and right node, stored in a nested hash table, like i did yesterday. sounds much nicer

htorque

maybe we'll soon see the "palazzo tree" :P

Octavian Damiean

12:53 PM

hello hello

Stefano Palazzo

ha! :)

hello @Octavian

htorque

@OctavianDamiean hi

Stefano Palazzo

I'm not really sure why you'd ever use a Heap yet. My perspective was finding "n largest", which a normal BST can do in O(log n)

Kaustubh P

hai!

Stefano Palazzo

hello @KaustubhP :)

Kaustubh P

1:02 PM

yo yo yo @StefanoPalazzo my man!

ssup homie?

lol, enough gangsta for a day!

Stefano Palazzo

hehe

election ends in seven hours!

Kaustubh P

yup! i am excited to see the results!

Stefano Palazzo

me too (:

Kaustubh P

yay, i crossed 1500 rep :D

Stefano Palazzo

nice!

Kaustubh P

1:07 PM

thanks. well, about the wish-list tag. Its just a tag, that can be browsed.

by people who are co-incidentally developers of the same app

Stefano Palazzo

I think it will encourage wishlist questions

I just made an argument for now, I'm looking forward to being proved wrong when someone else joins into the conversation

I also feared, by the way, that we should then, by the same token, have a "bug" tag

looks like [bug] is currently used for questions about the concept of a bug, and bug management and tracking, rather than specific bugs

Kaustubh P

hmm. well, some insight is certainly appreciated.

htorque

telling people that their question/problem is about a known bug tends to not get lotta rep points/accepts :D

Stefano Palazzo

I was kind of hoping someone would add a similar answer to mine, except beginning with "yes", so we can make them CW and vote on it, see if there's a clear consensus

(not that the votes decide upon the issue, but to get a feeling as to what people think about it)

Kaustubh P

@htorque and here i thought it was all about helping each other :P

htorque

1:15 PM

it is, it just isn't very motivating to get no comments to "yeah, it's a bug" like answers. :P

election ends in 6 hours - time to re-evaluate my choices :>

TheX

2:02 PM

hey gang

Stefano Palazzo

hi @thex

TheX

@StefanoPalazzo how are you?

Stefano Palazzo

very good, thanks for asking :)
yourself?

Kaustubh P

hi @TheX

:))

TheX

brb

back @StefanoPalazzo I am good, @KaustubhP hello

Kaustubh P

2:20 PM

where's @MarcoCeppi when you need him :P ?

TheX

@MarcoCeppi was eaten by aliens....

@TheX poor aliens.

I know right...

@KaustubhP I'm here.

@MarcoCeppi hi! thank god u are here! you mentioned once u work with centos, right?

Marco Ceppi

2:28 PM

Yes I do

Kaustubh P

well, its debian vs centOs all over again :/

is it safe to assume, that centOs is more locked up (ie safe) than debian?

Marco Ceppi

Yes, and no.

Stock installs of both CentOS and Debian are about the same with Security - except I think SELinux is enabled on CentOS which I usually have to disable.

TheX

it is probably more stable, as debian tends to be on the cutting edge

Marco Ceppi

@TheX That is about the most incorrect statement you can make about Debian.

TheX

@MarcoCeppi??

Marco Ceppi

2:31 PM

Debian is not cutting edge

TheX

then what am I thinking of?

Marco Ceppi

@TheX Ubuntu?

htorque

@TheX that's a lie i expect from every candidate, so it doesn't count :P

TheX

@MarcoCeppi no.. .isn't there a distro that uses a rolling update system... that always has the latest and greatest softwares?

Marco Ceppi

@KaustubhP There are no distros that are "more secure" than another. Every distro of Linux I've used requires security configurations to be made to satisfy every job I've done

Stefano Palazzo

2:33 PM

@TheX Arch Linux is like that, fedora is pretty cutting edge as well, but they have regular releases

Marco Ceppi

@TheX It's certainly not Debian. Doesn't Gentoo do that?

TheX

@htorque I promise that the canidates will do the best they can to fulfill their obligations

maybe it is fedora I am thinking off

htorque

oh no, wrong action - can i un-edit a chat post? :(

Kaustubh P

@MarcoCeppi to sum up my problem, I have a master db-server, that can be connected from the outside. the slave-db-server cant be, even though I have opened the firewalls. both can connect to each other, using the Private IPs. gues which is which?

TheX

that was odd...

@htorque I don't think so

Marco Ceppi

2:35 PM

@KaustubhP Based on your conversation prior CentOS is slave Ubuntu is Master?

htorque

ok, then let's do it the other way round :P

"Election closes in 5 hours." - any last minute pre-election promises? :-)

@TheX :P

Kaustubh P

@MarcoCeppi no, debian is the master.

(good memory) :D

Marco Ceppi

@KaustubhP Ah, yes this is Debian v CentOS

TheX

@htorque no, the candidates don't make promises for we all know promises are lies when it comes to politics and running for public office

Kaustubh P

i just turned of SELinux, lets see where that tux us.

Marco Ceppi

2:37 PM

I love the idea of SEL hate the current implementation

htorque

@TheX sure, but i want cake - err, lies. :P

TheX

the cake is a lie...

actually it wasn't there was a cake, you just couldn't have it...

htorque

isn't SEL the "pain-to-configure" security model?

Kaustubh P

@MarcoCeppi nope, dont work.

htorque

supposed to be better than AppArmor?

Marco Ceppi

2:39 PM

@htorque it's the pain alright

TheX

are any of you rich?

Marco Ceppi

@KaustubhP How is your network configured?

@TheX Yes, and the answer to your next question: No. :P

htorque

lol

Marco Ceppi

Disclaimer: I'm not really rich

TheX

i just wanted to know if you wanted to donate a new computer to my desk....

Marco Ceppi

2:40 PM

> ...answer to your next question: No.

TheX

lol

Marco Ceppi

:D

TheX

I guess I will have to continue to use that ipad then...

Kaustubh P

@MarcoCeppi well, its on the amazon cloud. 3 servers. one: master, debian. two: slave, centOS. three: beanstalk, centOS/

htorque

money is overrated... unless you want to buy something. :D

Marco Ceppi

2:42 PM

@KaustubhP If it makes you feel any better it took me 3 weeks to perfect our current CentOS 5 image. And to be honest in the last 3 weeks our Ubuntu Server population has gone from 5% of the infrastructure to 22%

We're making a shift away from RHEL

@KaustubhP Ah, didn't realize you were on the cloud - that adds a level of complexity to things

Kaustubh P

yeah, the virtualization :/

Marco Ceppi

Why not just use the Amazon RDS?

Scaling, slaving, backups - all taken care of you by Amazon

Kaustubh P

@MarcoCeppi RDS is mysql, we use mongodb.

Marco Ceppi

Ah, I just assumed you were using MySQL

Kaustubh P

thats ok :)

Marco Ceppi

2:46 PM

Do you have APF or anything like that running on the machine? What about the IPTables are the ports for MongoDB not opened?

Kaustubh P

Yes, i have the ports opened up too. I can connect to the master server, that is in the same security group as the slave.

Marco Ceppi

Can you SSH into the slave directly?

Kaustubh P

yup, ssh works.

and opening ports for a security group opens the ports for all the machines in the group, so the ports arent a problem.

ive been racking my brain all afternoon, and now evening. but cant pinpoint the exact problem.

Marco Ceppi

I'm not sure how MongoDB works - so sorry about that part - but if you can SSH into the the machine, and you've opened the MongoDB ports, the last thing I can think is a configuration issue on MongoDB - I know a lot of services need to "bind to an IP" if that's the case make sure it's listening for the right public IP

Kaustubh P

.yeah, you can specify ports for mongodb, if not, it uses the default port of 27017. that is open, and i can connect to the master, similar to mysql -h <IP>

its the slave thats being a pia for me.

i can connect to the slave :P

sorry, for the typo!

htorque

2:56 PM

hey, what's up with youtube? no youtube login without a linked google account?

Marco Ceppi

I think the problem either lies with slave MongoDB configuration or something weird on the CentOS server

Not to be an ass - why not just use a Debian image for the slave?

htorque

well, no more youtube then - any alternatives?

TheX

it would be cool if you could install ubuntu on the ipad :D

Kaustubh P

I guess we will have to. I want to get to the bottom of it, deadlines dont permit me to. Cant juggle work, home, life :'(

TheX

why no youtube?

Marco Ceppi

2:59 PM

@htorque You know Google owns Youtube, right?

htorque

yes

Marco Ceppi

So...just like all Google Services - you need a Google Account :)

TheX

vimeo is probably the most popular @htorque

video sharing service next to youtube

htorque

i don't want yet another account, and i also don't want to log out every time i was logged in to youtube, so my searches at google aren't linked to the account... oh dear

@TheX yeah, i will definitely check it out (as it's the only alternative i know :D)

TheX

@htorque actually there are thousands of them, a simple google search will reveal that :-P

htorque

3:03 PM

ok, but how many are any good?

google is a damn datenkrake ("data octopus"?)

TheX

I don't know the only two I have experience with is vimeo and youtube

the stuff on vimeo seems more polished then what is on youtybe.

htorque

as long as it plays the clips without tons of ads like those "thousands of free video sites" i'm fine with it :)

Welcome to Vimeo! You have just joined the best site in the Universe to upload and share all the types of videos you create.

now that's what i call self-confidence :D

TheX

@htorque i haven't seen a single add yet...

I mean in the videos...

before I should say

htorque

gong "Election closes in 4 hours."

Kaustubh P

I had voted in the first 3 hours.

that should give ou hints to whom I voted for.

and no, I havent changed my votes after that :)

htorque

3:13 PM

i've shuffled my initial three picks a couple of times (the priorities I mean), but now they are like when voting started :)

TheX

i voted within the first hour....

Bill Clinton got my first vote

Kaustubh P

@TheX you sure you voted at the right place?

TheX

uh... I think so...

no write ins?

Kaustubh P

remeber, he did not have relations with that woman.

TheX

haha Coke has killed thisamericanlife.org

telegraph.co.uk/foodanddrink/8324778/…

@KaustubhP I wouldn't admit to having relations with that women either...

htorque

3:26 PM

whew, waiting 30 minutes before the clip goes online is boooooo!

Kaustubh P

@TheX its all in the head ;;)

TheX

@htorque they have better compression then youtube

@htorque what is the video anyways?

htorque

nothing special. from time to time i upload some ubuntu clips.

TheX

oh...

Kaustubh P

`@MarcoCeppi I can now connect to the slave. Had to ddo with SELinux, atleast thats what I am thinking.

Marco Ceppi

3:33 PM

@KaustubhP Did you restart after you changed the SEL settings?

Kaustubh P

yeah, thats what took me so long. The instance was dangling in a stopping state for like 2o mins.

@MarcoCeppi thanks a lot, for the insights!

Marco Ceppi

@KaustubhP You're welcome. When it doubt it's probably SEL :P

Kaustubh P

lol, i am learning that :)

gotta google that.

oops, sorry :P

Oli

Anybody know when the results of the election are due? Are they instant (after voting ends) or is there a delay?

TheX

3:49 PM

@Oli six month delay, to allow time for recounts and any lawsuits that may evolve out of them :-P

Kaustubh P

@TheX :D

Marco Ceppi

@Oli You should be able to tally them with OpenSVG immediately - but the announcement comes after a few hours

Oli

I dare say there'll be a few people doing that in here

Stefano Palazzo

I'm going to assume I didn't make it, until someone here tells me (:

to prepare myself for failure

:P

Oli

@StefanoPalazzo Probably a healthier way of looking at it. I'm surprisingly nervous for something that is (in the scale of things) fairly insignificant

TheX

3:52 PM

I have prepared myself for failure too... but I think I have a reasonable guess as to why I am not going to be elected...

Kaustubh P

I hope I win, I have m fingers crossed.

Stefano Palazzo

It's the most important thing in the world, today at least (:

Kaustubh P

throws powder into a flame and chants mantras ॐ

Stefano Palazzo

I'm also hoping very much that my second and third choice win

Marco Ceppi

From the other Moderators, RE: Election tally

> It depends on how fast your users are. The moment the election ends, the votes can be read by people to parse, but the actual system doesn't update until a couple hours

Oli

3:55 PM

Well if Marco isn't re-elected, god help whoever has to fill his shoes. I think we'd have to petition SO Inc to have him re-added immediately.

TheX

@Oli that would take away from the democratic process...

if the community doesn't want @MarcoCeppi to be a moderator then they won't vote for him... or more people will vote for other candidates...

Oli

Democracy is overrated.

Marco Ceppi

If I'm not re-elected I'm still not going anywhere. I'll be around to help the new moderators settle into their roles

TheX

tell the egyptians that

Oli

@TheX Not saying it's not worth it, just that it doesn't always make the best decisions.

Stefano Palazzo

3:58 PM

I would be much more annoyed to not make it if a computer had decided it, at least with people I can tell myself they're just wrong :P

TheX

then the community will learn from their mistakes

Oli

7

Q: Removing folder named ~

This is the output of ls -l ls -l total 53484 drwxr-xr-x 3 root root 4096 2011-02-10 05:59 ~ -rw-r--r-- 1 root root 54313810 2011-02-13 05:09 jobs.jar -rw-r--r-- 1 root root 384035 2011-02-15 05:33 jobsLog.out I cant do rm -rf ~ because that will remove my home directory. What should ...

bash rm

TheX

just like we learned from our mistake of putting Obama in the hot seat

Oli

That thread is getting a silly number of votes today. Odd.

Stefano Palazzo

@Oli you're answer on that is pretty great

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