I am trying to blow up a directory in my docker container to test maintenance scripts. I've tried logging to a file in an indefinite while loop -- this was extremely slow. Fast way to do this programmatically?
How can I quickly create a large file on a Linux () system?   will do the job, but reading from /dev/zero and writing to the drive can take a long time when you need a file several hundreds of GBs in size for testing... If you need to do that repeatedly, the time really adds up.  I don't care about the contents of the file, I just want it to be created quickly. How can this be done?  Using a sparse file won't work for this. I need the file to be allocated disk space.
I recently printed a paper that asks to prove the "amazing" claim that for all $a_1,a_2,\dots$  $$\sum_{k=1}^\infty\frac{a_1a_2\cdots a_{k-1}}{(x+a_1)\cdots(x+a_k)}=\frac{1}{x}$$  and thus (probably) that  $$\zeta(3)=\frac{5}{2}\sum_{n=1}^\infty {2n\choose n}^{-1}\frac{(-1)^{n-1}}{n^3}$$  Since the paper gives no information on $a_n$, should it be possible to prove that the relation holds for any "context-reasonable" $a_1$? For example, letting $a_n=1$ gives  $$\sum_{k=1}^\infty\frac{1}{(x+1)^k}=\frac{1}{x}$$  which is true.  The article is How do I run specific sudo commands without a password? Android 4.1 (Jelly Bean) was announced at Google I|O 2012 on June 27, 2012.  (You can review  at the official Android Developer's site.)  Of course, not all devices will get this update right away and others won't get it at all. Each manufacturer and carrier often choose to add their custom modifications which tend to delay the official release.  When will each device get Android 4.1, either officially or unofficially, if ever?  See also: Word for person unwilling to share information What do you call a person who is unwilling to share information? Improving "demonstrate a minimal understanding" close reason Note: the eventual outcome of this discussion involved dropping this particular off-topic reason, along with other changes. See:  &nbsp; &mdash;Shog     I was using the reason "demonstrate a minimal understanding" myself quite frequently, but the more I review, the more I have doubts about it and I think this reason can either be dropped entirely or at least rephrased, so I started to use "problems with code you've written must describe the specific problem" instead:     Questions asking for code must demonstrate a minimal understanding of the problem being solved.   So the poster has posted some description, maybe even a snippet of code and in his mind that already proves that he has that minimal understanding required. After all he described the problem and what he tried to solve. So telling him that he lacks that understanding is rather rude, and from the posters point of view doesn't even apply. What both version of the reason not emphasize is that a description of a problem is not various versions of     it doesn't work   but that we rather mean really specific details (see below). I can often see in the reopen review queue that the "improved" version just includes a more verbatim description, while what usually would be expected is some specific error message, a trace or a log, or whatever applies.  Then it continues with:     Include attempted solutions, why they didn't work, and the expected results. See also: Stack Overflow question checklist   comparing it to:     problems with code you've written must describe the specific problem — and include valid code to reproduce it — in the question itself. See SSCCE.org for guidance.   Which says essentially the same, only in more detail.   So the "minimum understanding" reason is IMO a more rude version of the reason telling the user that an SSCCE is missing.  The intent of giving this reason is to tell the user that he needs to give exact details to be able to help him, so IMO a checklist would be much better. Something like:     Your question was closed because it may not provide enough details. Things you can do to improve your question to get an answer include:         Format the code in a way that makes it readable and easily understandable.   Provide the smallest working sample of code demonstrating the problem (link to SSCCE)   Include your input and output.   If applicable provide logs (i.e. Android debugging log, stack trace, etc.).   If applicable provide the exact error messages (compiler, etc.).      And something like this should be best included already in the banner that appears when a question is closed instead of being hidden in some pages you often enough have to actively looking for.  It might be helpful to adjust this, based on the tags or close reason, as I realize that I'm more focused on the programming area, and the above list may not apply to other areas of SO.  Update  Another thing I forgot to mention (but wanted to) is this:     Questions asking for code   Is IMO essentially an invitation of the type of questions     I have a problem, can you provide the solution? (with an optional please)   while     Questions concerning problems with code you've written   puts at least some emphasis on the fact that the poster has to put some effort himself in trying to solve the problem by providing the code which he used to attempt the solution. I asked about it on  and they told me to post it here.  Probably need to add the :active to the :hover meta class or something like that.  Example:      Hammer Time Is there a free program to (batch) change photo file's date to match EXIF? I want to specify a directory and have the software find all the photos in the directory and its sub-directories, and if they contain EXIF date/time, it sets their filesystem timestamp to match the EXIF. Suppose the proper length of a train is longer than that of a bridge, and the bridge can't bear the total weight of the train but can bear it partially. As the train goes very fast, it becomes shorter than the bridge and it can be entirely on the bridge. As a result, the bridge will collapse. However, in the train's frame, the train is even longer than the bridge, and it is only partially on the bridge; so the bridge will not collapse. What is the solution to this paradox? Resizing an Image without losing any quality Polynomial in $n$ variables Let $f$ be polynomial in $n$ variables. If we have $f(a_1,\ldots,a_n) = 0, a_i \in S_i$ and $S_1,\ldots,S_n$ are infinite subsets of a field $k$, how can I show that $f=0$? Cold fusion is being mentioned a lot lately because of some new setup that apparently works. This is an unverified claim.  See for example:         ( of that last link in the Wayback Machine, given frequent  from that page.)   While we should give the scientific community time to evaluate the set up and eventually replicate the results, there is undoubtedly some skepticism that cold fusion would work at all, because the claim is quite extraordinary.  In the past, after Fleischmann and Pons announced their cold fusion results, in perfectly good faith, they were proven wrong by subsequent experiments.  What are the experimental realities that make Fleischmann and Pons style cold fusions experiments easy to get wrong?  Would the same risks apply to this new set up? Where did Magister Illyrio Mopatis get the dragon eggs from? . While the reasons for his doing this are not yet public, this is a real loss of a valuable service. Does anyone know of similar services available to the general public?  Edit:  is definitely relevant, but that approach is more appropriate for finding top journals rather than identifying bottom ones. I.e., following that method would probably exclude lots of valid, lower-tier journals. Are there any approaches to easily identifying a predatory publisher? C# Change A Button's Background Color I have been using LaTeX for a long time now, but still all my document files look a bit messy. Now I want to get rid of this bad habit and get some order into my code.  That is why I am wondering whether there are any coding style guidelines for LaTeX. Not necessarily anything official. It could for example make recommendations on how to format your code with respect to:   Setting comments in the text/preamble Whether to highlight sections/subsections etc. by some comments How to indent environements How to organize your preamble to make it readable etc.   If nothing as such exists (yet), it would be great if you could just post how you do it if you think your code looks rather nice. Install brother dcp195c, receiving data but nothing happens, why? Can someone please help me to install brother dcp195c drivers on Ubuntu v12?  Using the default driver, the printer says that it is receiving data but nothing happens. 7 month old wants to sleep on its belly -- is it safe? HTML text input allow only numeric input Is there a quick way to set an HTML text input (&lt;input type=text /&gt;) to only allow numeric keystrokes (plus '.')? Routing in home LAN I'm trying to understand some basic concepts of networking. I have following home LAN:     Is it right (like above) to have 2 NIC's each one having 2 different gateways on one station? There PC2 have 2 NICs - the first's one gateway is 192.168.0.1 the second's 192.168.1.1? Initially (just after system startup) the ip table is like that:  192.168.0.0    255.255.255.0         On-link      192.168.0.11    276 192.168.0.11   255.255.255.255       On-link      192.168.0.11    276 192.168.0.255  255.255.255.255       On-link      192.168.0.11    276    and when i run netcat:  nc -zv -s 192.168.0.11 192.168.0.11 80    to test if port 80 is open it works - the port 80 is indeed open. But when i remove the 192.168.0.11 route i got "TIMEOUT" on nc test. Shouldn't it pick 192.168.0.0 route and work? Moreover when i add the route manually:   route add 192.168.0.11 mask 255.255.255.255 0.0.0.0   it still doesn't work! I can't change the metric to desired value. When i run for eg. route change 192.168.0.11 mask 255.255.255.255 192.168.0.11 metric 500 the result metric is't 500 but 520! (no matter if auto-metric is enabled or not)? Is there any connection between -s flag (local source address) in netcat and routing table's Interface column? Today a couple of buffer overflows in NTP were announced , . It looks like updating my system to fix these issues is in order.   How can I find out if they have been fixed in the Ubuntu repositories, such that if I were to run:   sudo apt-get update sudo apt-get upgrade   then the fix would get installed and the vulnerability closed?   Edit: The selected answer specifically addresses the question of how to identify if a given CVE has been fixed or not, "Does Ubuntu generally post timely security updates?"  is certainly related but not identical