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• How to distinguish between virtual disk image formats?

  - by Jakub Žitný

  There is huge number of different formats for virtual storage files for desktop and server purposes (vmdk, qcow2, vdi, vdk, etc.). I'm writing a little script for manipulating them and would like the script to be able to distinguish between them. Of course, it can be done via extension, but I want this to be more reliable. I tried commands file or qemu-img, but the results are not quite clear. Any idea improving my methods?

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• Is the Cloud ready for an Enterprise Java web application? Seeking a JEE hosting advice.

  - by Jakub Holý

  Greetings to all the smart people around here! I'd like to ask whether it is feasible or a good idea at all to deploy a Java enterprise web application to a Cloud such as Amazon EC2. More exactly, I'm looking for infrastructure options for an application that shall handle few hundred users with long but neither CPU nor memory intensive sessions. I'm considering dedicated servers, virtual private servers (VPSs) and EC2. I've noticed that there is a project called JBoss Cloud so people are working on enabling such a deployment, on the other hand it doesn't seem to be mature yet and I'm not sure that the cloud is ready for this kind of applications, which differs from the typical cloud-based applications like Twitter. Would you recommend to deploy it to the cloud? What are the pros and cons? The application is a Java EE 5 web application whose main function is to enable users to compose their own customized Product by combining the available Parts. It uses stateless and stateful session beans and JPA for persistence of entities to a RDBMS and fetches information about Parts from the company's inventory system via a web service. Aside of external users it's used also by few internal ones, who are authenticated against the company's LDAP. The application should handle around 300-400 concurrent users building their product and should be reasonably scalable and available though these qualities are only of a medium importance at this stage. I've proposed an architecture consisting of a firewall (FW) and load balancer supporting sticky sessions and https (in the Cloud this would be replaced with EC2's Elastic Load Balancing service and FW on the app. servers, in a physical architecture the load-balancer would be a HW), then two physical clustered application servers combined with web servers (so that if one fails, a user doesn't loose his/her long built product) and finally a database server. The DB server would need a slave backup instance that can replace the master instance if it fails. This should provide reasonable availability and fault tolerance and provide good scalability as long as a single RDBMS can keep with the load, which should be OK for quite a while because most of the operations are done in the memory using a stateful bean and only occasionally stored or retrieved from the DB and the amount of data is low too. A problematic part could be the dependency on the remote inventory system webservice but with good caching of its outputs in the application it should be OK too. Unfortunately I've only vague idea of the system resources (memory size, number and speed of CPUs/cores) that such an "average Java EE application" for few hundred users needs. My rough and mostly unfounded estimate based on actual Amazon offerings is that 1.7GB and a single, 2-core "modern CPU" with speed around 2.5GHz (the High-CPU Medium Instance) should be sufficient for any of the two application servers (since we can handle higher load by provisioning more of them). Alternatively I would consider using the Large instance (64b, 7.5GB RAM, 2 cores at 1GHz) So my question is whether such a deployment to the cloud is technically and financially feasible or whether dedicated/VPS servers would be a better option and whether there are some real-world experiences with something similar. Thank you very much! /Jakub Holy PS: I've found the JBoss EAP in a Cloud Case Study that shows that it is possible to deploy a real-world Java EE application to the EC2 cloud but unfortunately there're no details regarding topology, instance types, or anything :-(

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• Can I legally publish my Fortran 90 wrappers to nVidias CUFFT library (from CUDA SDK)?

  - by Jakub Narebski

  From a legal standpoint (licensing issues), can I legally in agreement with license publish Fortran 90 wrappers (bindings) to CUFFT library from nVidia CUDA Toolkit, under some open source license (either CC0 i.e. public domain, or some kind of permissive license like BSD). nVidia provides only C bindings with their CUDA SDK. Header files contain the following text: /* * Copyright 1993-2011 NVIDIA Corporation. All rights reserved. * * NOTICE TO LICENSEE: * * This source code and/or documentation ("Licensed Deliverables") are * subject to NVIDIA intellectual property rights under U.S. and * international Copyright laws. * * These Licensed Deliverables contained herein is PROPRIETARY and * CONFIDENTIAL to NVIDIA and is being provided under the terms and * conditions of a form of NVIDIA software license agreement by and * between NVIDIA and Licensee ("License Agreement") or electronically * accepted by Licensee. Notwithstanding any terms or conditions to * the contrary in the License Agreement, reproduction or disclosure * of the Licensed Deliverables to any third party without the express * written consent of NVIDIA is prohibited. The License.txt file includes the following fragment Source Code: Developer shall have the right to modify and create derivative works with the Source Code. Developer shall own any derivative works ("Derivatives") it creates to the Source Code, provided that Developer uses the Materials in accordance with the terms and conditions of this Agreement. Developer may distribute the Derivatives, provided that all NVIDIA copyright notices and trademarks are propagated and used properly and the Derivatives include the following statement: "This software contains source code provided by NVIDIA Corporation."

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• Jersey 1.8 is released

  - by Jakub Podlesak

  On the last Friday, we have released the 1.8 version of Jersey, the open source, production quality, reference implementation of JAX-RS. The JAX-RS 1.1 specification is available at the JCP web site and also available in non-normative HTML here. For an overview of JAX-RS features read the Jersey user guide. To get started with Jersey read the getting started section of that guide. To understand more about what Jersey depends on read the dependencies section of that guide. See change log here. This, 1.8, version of Jersey is going to be integrated into GlassFish 3.1.1 and contains bug fixes mainly. The most important fix from this perspective is included in the JAX-RS/EJB integration layer. It is now possible to implement JAX-RS resources as EJB Session beans, which implement local and/or remote interfaces. This functionality was broken in previous releases. Another great addition should come into the client space, where Pavel has already done some preparation in the client API (including some breaking changes there) for the non-blocking asynchronous client feature. The implementation is already part of the experimental Jersey space and should be included as part of the stable Jersey bits in some of the coming releases. For feedback send email to: [email protected] (archived here) or log bugs/features here.

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• Is there a ways to see granular per-visit data in Google Analytics?

  - by jakub.g

  I've started using Google Analytics very recently and I'm a bit lost with the sea of options (have been using Sitemeter before for some time). I've clicked through the service a lot but couldn't find what I'm accustomed to. I can see multitude of aggregated statistics in GA like: charts of browser share lists of country share lists of most visited URLs within the page and so on, but I would actually like to analyze each of the visits themselves. Something like: User X, France, Chrome, 7 pageviews between 18:01 and 18:15, entered on a.htm and exited on b.htm User Y, UK, Firefox, 1 pageview at 18:20, entered on c.htm Is there an easy way to see the reports in this way (perhaps by clicking a link to a separate page to see that particular session's stats)? How to navigate there if so?

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• Jersey 2.0 Integrated into GlassFish 4.0

  - by Jakub Podlesak

  The latest promoted build of GlassFish 4.0 (glassfish-4.0-b43.zip) now contains upgraded Jersey version, 2.0-m05. Users are getting an early access to the implementation of some parts of the JAX-RS 2.0 API Early Draft Review 3. The appropriate JAX-RS bundle, version 2.0-m09 , gets bundled into GlassFish 4.0 as well. What should work The simple answer is: all the basic stuff. We have particularly tested the following two examples: simple hello world webapp multipart webapp Both above linked archives contain adjusted projects, so that resulting war files do not bundle any Jersey dependencies. Both also use Jersey 2 specific Servlet class, org.glassfish.jersey.servlet.ServletContainer, for deployment. See Martin's blog post on how to package war applications capable of running with both Jersey 1 and Jersey 2 ServletContainer classes. What has not been covered yet The main areas, which have not been touched yet in Jersey 2 are: EJB integration CDI integration Validation These are also the areas where we are going to spend the most of our cycles in the coming month.

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• Are any Zotac Zboxs suitable as HTPC / media centres?

  - by Jakub

  Are any Zotac Zboxes suitable as HTPC / media centres? I'm after a fanless HTPC client in the living room to work with my MythTV server in my home office. I like the small compact form factor of the Zbox but what little I could find by Googling didn't clearly recommend any particular models for Ubuntu / MythTV / XBMC. Can anyone recommend any models that work with little hassle? Or, if there aren't any, are there other more Linux-friendly small format fanless PCs I should be looking at instead?

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• When do you use float and when do you use double

  - by Jakub Zaverka

  Frequently in my programming experience I need to make a decision whether I should use float or double for my real numbers. Sometimes I go for float, sometimes I go for double, but really this feels more subjective. If I would be confronted to defend my decision, I would probably not give sound reasons. When do you use float and when do you use double? Do you always use double, only when memory constraints are present you go for float? Or you use always float unless the precision requirement requires you to use double? Are there some substantial differences regarding computational complexity of basic arithemtics between float and double? What are the pros and cons of using float or double? And have you even used long double?

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• What makes it hard to protect from hacks/bots in BF3 and Quake Live?

  - by Jakub P.

  After playing these games, asking other players/admins, and reading online I am led to believe that Quake Live and Battlefield 3 are frequented by bots and there are plenty of hacks of various kinds. I'm confused how this is possible, or even easy seeing how many players have access to these kinds of "tools" (sic). Isn't it possible for the game authors to digitally sign the game executables so that when they run, the server can ensure only the allowed client is sending commands, thus preventing any kind of abuse? I.e. every player command would be signed by a private key, or symmetrically encrypted (not sure which would make more sense). I understand that players can look at the running executable's behavior (memory etc.), but if games are apparently so easy to hack, shouldn't most apps be hacked as well (e.g. Skype, all DRM running on Windows etc.)?

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• Is the Cloud ready for an Enterprise Java web application? Seeking a JEE hosting advice.

  - by Jakub Holý

  Greetings to all the smart people around here! I'd like to ask whether it is feasible or a good idea at all to deploy a Java enterprise web application to a Cloud such as Amazon EC2. More exactly, I'm looking for infrastructure options for an application that shall handle few hundred users with long but neither CPU nor memory intensive sessions. I'm considering dedicated servers, virtual private servers (VPSs) and EC2. I've noticed that there is a project called JBoss Cloud so people are working on enabling such a deployment, on the other hand it doesn't seem to be mature yet and I'm not sure that the cloud is ready for this kind of applications, which differs from the typical cloud-based applications like Twitter. Would you recommend to deploy it to the cloud? What are the pros and cons? The application is a Java EE 5 web application whose main function is to enable users to compose their own customized Product by combining the available Parts. It uses stateless and stateful session beans and JPA for persistence of entities to a RDBMS and fetches information about Parts from the company's inventory system via a web service. Aside of external users it's used also by few internal ones, who are authenticated against the company's LDAP. The application should handle around 300-400 concurrent users building their product and should be reasonably scalable and available though these qualities are only of a medium importance at this stage. I've proposed an architecture consisting of a firewall (FW) and load balancer supporting sticky sessions and https (in the Cloud this would be replaced with EC2's Elastic Load Balancing service and FW on the app. servers, in a physical architecture the load-balancer would be a HW), then two physical clustered application servers combined with web servers (so that if one fails, a user doesn't loose his/her long built product) and finally a database server. The DB server would need a slave backup instance that can replace the master instance if it fails. This should provide reasonable availability and fault tolerance and provide good scalability as long as a single RDBMS can keep with the load, which should be OK for quite a while because most of the operations are done in the memory using a stateful bean and only occasionally stored or retrieved from the DB and the amount of data is low too. A problematic part could be the dependency on the remote inventory system webservice but with good caching of its outputs in the application it should be OK too. Unfortunately I've only vague idea of the system resources (memory size, number and speed of CPUs/cores) that such an "average Java EE application" for few hundred users needs. My rough and mostly unfounded estimate based on actual Amazon offerings is that 1.7GB and a single, 2-core "modern CPU" with speed around 2.5GHz (the High-CPU Medium Instance) should be sufficient for any of the two application servers (since we can handle higher load by provisioning more of them). Alternatively I would consider using the Large instance (64b, 7.5GB RAM, 2 cores at 1GHz) So my question is whether such a deployment to the cloud is technically and financially feasible or whether dedicated/VPS servers would be a better option and whether there are some real-world experiences with something similar. Thank you very much! /Jakub Holy PS: I've found the JBoss EAP in a Cloud Case Study that shows that it is possible to deploy a real-world Java EE application to the EC2 cloud but unfortunately there're no details regarding topology, instance types, or anything :-(

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• How to secure JBoss application server using SELinux

  - by Jakub Elias

  I want to secure RedHat 5.4 application server by SELinux (targeted policy) and have several questions 1, where can i get SELinux sources (/etc/selinux//src/policy/)There seems to be no such package on install cd .. 2, how to restrict user rights (for example user jboss could not modify /etc/my.cnf) 3, how to configure JBoss application server to work under SELinux Although i read many documents from NSA the whole topic is still not clear for me.What i want is to basically protect filesystem in case one account is broken.I cannot find any materials about securing jboss server using either chroot jail, ACLs or SELinux ....

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• What external comment system to use for Jekyll powered blog?

  - by Jakub Narebski

  What external comment system (i.e. something like Disqus or perhaps even Hacker News / YCombinator) would you recommend for Jekyll-powered blog (in this case: blog on GitHub Pages), or in more generic term for blog aware static site generator powered blog (which includes beside Jekyll also for example ikiwiki or xfire's growl)? Because a blog without comments is not a blog :-).

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• Linux LiveCD (or LiveUSB) with custom xorg.conf

  - by Jakub Narebski

  Is there some Live Linux distribution (on CD, DVD or USB), which allow one to use specific xorg.conf file, i.e. specific X11 configuration? The problem I am trying to solve is to find Linux Live distribution for web browsing which would work well with NEC LCD 22WV monitor. It is supposedly DDCCCI capable, but X.Org X Window System autoconfiguration fails to detect proper modeline, and uses fallback 800x600 screen resolution, instead of preferred screen resolution of 1680x1050.

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• Force dual-mono audio (L+L or R+R) in Youtube video playback for one-channel audio movies

  - by jakub.g

  Occasionally, I find Youtube videos that have only one audio channel (only left or only right); example video (left channel only). This is quite annoying, especially with headphones on, as I hear sound in one ear, and no sound in the other. So, I want to be able to easily force dual mono (Left+Left or Right+Right) when I find that kind of video, and switch to normal stereo after I finish watching it. I have my headphones plugged well / I don't create audio/video - I want it for real-time playback only, In Windows audio config, setting balance 100% to Left / Right doesn't help (I have either still only left when moved to left, and no sound at all when moved to right), I've checked all the configurations in Control Panel > Sounds and Audio Devices > Audio > Sound Playback > Advanced like suggested in this post, in conjunction with moving balance left/right, and it doesn't seem to have any impact on actual sound I hear in headphones, No need to mix L with R, I just want L+L or R+R, I prefer software solutions to buying a stereo-to-mono adapter, Free solutions please, no $$$ ones, neither trials etc., In Control Panel > Realtek HD Sound Effect Manager I can turn on various mumbo-jumbo effects like: Concert Hall / Hangar / Bathroom / whatever environment (and in fact it makes the sound appear in two ears, but well, it's ridiculous to do this;), but there is no Dual Mono option. Finally, I know I can force L+L or R+R in VLC Player which supports Youtube (well, a little hack is needed, because Youtube internals change from time to time) but it is not very convenient to launch VLC just to play Youtube video - I want to keep it in the browser, I use Firefox generally (but well, if I don't find easier way, I will launch it in VLC).

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• How to measure disk performance?

  - by Jakub Šturc

  I am going to "fix" a friend's computer this weekend. By the symptoms he describes it looks like he has a disk performance problem with his 5400 rpm disk. I want to be sure that disk is the problem so I want to "scientificaly" measure the performance. Which tools do you recommend me for this job? Is there any standard set of numbers I can compare the result of measurement with?

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• Apache Unclean shutdown of previous apache run

  - by Jakub Arnold

  I'm having problem with running Apache2.2 on my Vista machine. When I clean install Apache it works just fine, but after I installed PHP, I'm getting this error message in logs. [Fri Oct 23 21:29:02 2009] [warn] pid file C:/Dev/Apache2.2/logs/httpd.pid overwritten -- Unclean shutdown of previous Apache run? Apache service was stopped when installing PHP. I did only one shutdown before instalation via Apache Service Monitor. Deleting httpd.pid and starting again doesn't help. I even tried to lookup process with PID in that file, but there is no such process.

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• Options to optimize lotus notes 8.5.X

  - by Jakub

  Has anyone found actually useful optimization methods for the bulky, fat, eclipse giant, nuissance that is Lotus Notes 8.5? I want it to be fast, and not eat up system resources like crazy while I run it ALL day (as it is my company's corporate mail / cal / scheduling solution). I've tried various hacks for the JVM heap size (if I recall correctly). None really bring a performance improvement. I have a dual core cpu, if that helps (I tried going the route of optimizing JAVA for 2 cores in hopes it would work, but seen no speed improvement). Notes is just sooo bloated, anyone have any suggestions to optimize/mod this thing so it is more responsive and less of a resource hog. Note: I don't want to switch to the web version, or the standard stripped down versions, I am aware of those, I just cannot since we don't run those internally for the company.

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• Anyone else being hit by traffic on TCP port 11370

  - by Jakub

  I've been watching my logs (Ubuntu 9.10 server) and dunno about any of you but I am getting a ton of traffic from sources like Russia, Romania, etc.. on port 11370 (my iptables are logndrop'ing it. But was just curious). Some googling revealed this info: http://www.keysigning.org/sks/ -which seems to use port 11370 & 11371 Could that be the service they are scanning for (i don't run it)? ICS shows this: https://isc.incidents.org/port.html?port=11370 Just curious what you guys think and if anyone has seen this before? If need be I can post my log on here, but its just a dropped log of TCP port 11370 from various IPs. Thought it was strange as thats the ONLY Port I seem to repeatedly be hit on (from logs). I'm running on a Linode (VPS) if that matters to annyone.

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• X-Window Modeline for high resolution modes on NEC LCD 22WV monitor

  - by Jakub Narebski

  What should look like X Window System (X.Org) modeline to be put in xorg.conf, for high resolution (incuding recommended 1680x1050 @ 50Hz resolution) for 22" NEC LCD 22WV monitor? X.Org autodetect correctly only 800x600 and lower resolution SVGA modes, unfortunately. How can I generate proper "Modeline" line for xorg.conf? Is information included in NEC_Datasheet_LCD22WV-english.pdf enough (found on NEC LCD 22WV product info page)? What tools there are available to generate proper modeline for a LCD monitor for Linux? MS Windows (MS Windows XP Home) correctly detects and use 1680x1050 resolution; can I somehow get modeline information from MS Windows?

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• Distributed computing for a company? Is there such a 'free' thing?

  - by Jakub

  I am new to the whole distributed computing / cloud thing. But I had an idea at work for our multimedia stuff like movie encoding / cpu intensive things tasks (which sometimes take a few hours). Is there a 'free' (linux?) way to go about using a Windows machine, and offsetting those cpu cycles for that task to say 10 servers that are generally idle (cpu wise)? I'm just curious if there is a way to do this or am I just grasping at straws here. My thought is that a 'cloud' setup would achieve this, however like I stated initially, I am a total newbie when it comes to it. This is just an idea, looking for some thoughts? Anyone achieve this?

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• What's the best solution for file sharing in my case? DAS or NAS?

  - by jakub

  I want to have in my network small, cheap and energy efficient server with will be fully customizable (Gnu/Linux, OpenBSD). What is more I want to have big, redundant storage in my network and access to it via server. I have already small terminal without hard drive (no SATA/PATA, one drive on USB) which works fine. I don't want to buy big server, or to use regular computer for that. It's not cheap. I thought about a small case (ITX?), and cheap computer in this with SATA ports, but I cannot find anything interesting :( I thought about NAS in network and server independently and booting server from NAS, I'm not sure which technologies will be good for that, and I don't know what with performance. Direct connection to NAS through network from workstation is next pro for that. What do you think about DAS? It will be good for that?

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• What is the solid Windows Server 2008 VPS hosting (preferably) in Europe?

  - by Jakub Šturc

  I am looking for Windows Server 2008 VPS hosting to host a few sites/apps with special needs. I spend few hours googling but I am not satisfied with the result. I looks to me that this business is full of crap. Two thirds of the reviews seems to be faked and advertised offers is unavailable or contains some hidden fee. So my question is which VPS hosting with Windows Server 2008 do you recommend? I slightly prefer data center in Europe and euro payment it isn't deal breaker. Note: I didn't made question community wiki because I am interested in answers from users with some reputation and I want to preserve theirs answers.

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• Win7 Ultimate 64bit not finding my SSD, any ideas?

  - by Jakub

  So I am trying to install Windows 7 Ultimate 64bit on my new SSD (Kingston SNVP325-S2/64GB) and I have unplugged my other drives (for the install only). The SSD is detected by BIOS, I am running the latest Firmware for my motherboard P5N-E SLI (775 socket). Upon getting the Windows 7 install screen, it gives me a 'no drives detected'. I have tried Load Driver and downloding nForce drivers (latest for Win7 64bit signed WHQL) results in a message of (something like) "To continue please click Load Driver and load 32-bit and signed 64-bit drivers... blah blah" ... basically it does NOT accept my nForce SATA drivers, nor my 2ndary SATA drivers (JMicron? can't recall the exact name now). I have tried F8 at loading to 'disable driver signing' in hopes that it was an unsigned driver, however nothing works. The SSD is not detected by the Windos 7 installer. I wasted 4 hours on this last night, and gave up, and got nowhere. Anyone heard / ran into this issue before? How can I get the drive detected? Some more details: - Kingston SNVP325-S2/64GB V+ SSD - ASUS P5N-E SLI MOBO - 8GB RAM A-DATA (memory is checked out and fine)

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• Artefacts during HDV capture

  - by Jakub Konecki

  When I try to capture HDV video stream from a Canon HV20 camera to a Dell Studio 1558 (Intel i7 720qm) laptop running Win 7 Home Premium x64, the image appears with a very annoying noise - it contains block artefacts. Something is wrong with the Fire Wire controller (Ricoh 1304 OHCI host controller, build-in). Tried changing the driver to legacy one to no avail. This does not happen with DV stream. I'm using a Belkin cable. The capture works OK on another machine.

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• Is there a way to correct wrongly typed password / abort the operation while on password prompt in the console in MINGW32?

  - by jakub.g

  I sometimes mistype a password when being asked for it, e.g. by Git when pushing to remote repository. The password is not displayed (even masked as asterisks) in the console. Is there a way either to correct the password, or to abort the operation? Backspace for editing and CtrlC for aborting do not seem to work. I want to save some time instead of waiting for the remote authentication to fail, or providing a bad password, then Enter, CtrlC. Edit: Unfortunately CtrlU doesn't work for me (MINGW32 @ Windows XP). Any other guesses?

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