I would like to set an environment variable (that we'll call "TEST") to store the path to a sub-directory of my home directory : something like /home/myself/dir/. I would like to use the $HOME variable so that the system can get a path that is valid for any user on the system (provided they have a directory called "dir" in their home folder). I tried several possibilities, but could not get it working. Here is one of my tries:  export TEST='$HOME/dir'   We can check that the variable has indeed been created :  env | grep TEST   Which returns:  TEST=$HOME/bin   So far so good. However this is where things get tough :  cd $TEST   Returns:  bash: cd: $HOME/bin: No such file or directory   However following variant works:  eval cd $TEST   Is there any way to obtain the same result, but without invoking eval?
I was wanting to initialize some strings at the top of my script with variables that have no yet been set, such as:  str1='I went to ${PLACE} and saw ${EVENT}' str2='If you do ${ACTION} you will ${RESULT}'   and then later on PLACE, EVENT, ACTION, and RESULT will be set. I want to then be able to print my strings out with the variables expanded. Is my only option eval? This seems to work:  eval "echo ${str1}"   is this standard? is there a better way to do this? It would be nice to not run eval considering the variables could be anything.
What do damage buffs affect? In Overwatch, there are several ways to buff the damage dealt by a hero: the alternate fire of Mercy's Caduceus Staff, Ana's Nano Boost, and Orisa's Supercharger. Are they all governed by the same rules? What can they affect, or not affect?  This question exists to have a single reference point for the many, many questions that have been asked, instead of having to update each answer individually when game mechanics change Can you stay in Turkey for over 90 days within the 180 day visa period but split over different visits? The Turkish e-visa is valid for a period of 180 days and allows you to stay for a maximum of 90 days. Am I allowed to stay for say 50 days, then another 50 days, over two different visits within the 180 day period?  I'm looking at the e-visa website  and it doesn't seem to be too clear on this. Graphics issues after/while installing Ubuntu 16.04/16.10 with NVIDIA graphics I installed or upgraded to Ubuntu 16.04, but I'm having some problems with my graphics card.   The display is blank The display flickers Items on the screen do not display correctly Certain programs complain of graphics issues The computer boots to low-graphics mode Your specific issue may not be here, but try the solutions described in the answers anyway.   This question is very broad, but each one of these issues likely has one solution.    If you are experiencing a login loop, check the last part of my answer.    If you experience one of the listed issues and have your own solution (mine didn't work, or there's a faster way), feel free to post another POLITE answer, describing your problem and how you fixed it.    Those attempting to install Ubuntu, please refer to the section titled: If you are unable to enter a TTY or are trying to install Ubuntu. Is it correct to use Bernoulli's theorem to explain that a disk floats in the air? Should the correct explanation be based on Boyle's law? In this video, a device is introduced from 1 minute to 18 seconds. After entering the air, the disc at the bottom of the device will be suspended in the air. The video explains that this is because of the Bernoulli effect, but I think this explanation is incorrect, because the disc gap, the radial volume is increasing. Therefore, the reason why the disk is suspended is that the air volume becomes larger, so the pressure decreases (according to Boyle's law). If the air moves along the radial direction at a constant speed, the volume of the air must be constantly increasing, right? So the pressure is decreasing, right? I have a simple question.     over centuries / for centuries   what is the difference?  Thank you. Custom question lists April status update Previous posts:                           After a long hiatus, a new Custom Question Lists update is out with a fresh new design.  What's shipped?  If you are participating in the Custom Question List alpha (by ), you'll see some brand new UI components when viewing question lists:  New tab bar and editor    Based on your feedback, we decided to rethink the whole UI, removing some confusing and redundant components, and bringing back some much loved pieces.  The new design is closer to "the existing question lists with advanced options" than "a radically new experience".  Huge shoutouts to our new designer, , for making this new design possible and to  for picking up development while I was on sabbatical!  Some important notes for existing testers:   The summary is back in its rightful place next to the tab bar.  If bounty or unanswered filters applied, the summary provides a clearer explanation of what you're looking at, inspired by /unanswered. The "Filter" and "Sort" popovers are gone. Sort was too similar to the existing tabs, and Filter was a form in a popover. (how were you supposed to submit or cancel?)  Now there's a dedicated UI for filtering. The complex "Create" and "Edit" modals are gone.  Now you just configure your list with the same UI as if you were filtering and click "Save filter" when you're ready to save. You can preview your changes before updating a filter.  Editing a saved filter and clicking apply shows you your new options while remembering what filter you were looking at.  You can then click "Save filter" to either update your existing filter or create a new one. We handle responsive better.  The tab bar has been set up so it compresses more naturally on narrower browsers and mobile devices.   New sidebar widget    A new right-sidebar widget has been added, similar to Watched Tags, to give you more direct access to your saved lists.  This is where indicators will live in Phase 3 (which I swear we are actually going to ship).  Please give it a try.  If you have any questions, bugs, or feedback, you can reply to this post directly or add a new question with the  tag.  A wider alpha  Since we're nearing launch, we're expanding the alpha out to the whole network.  So feel free to try this out on any site you frequent, to help suss out any site-specific issues.  What's next?  As always, Phase 3 of this project is adding indicators for new content, now in the right sidebar widget.  There's increasing interest in this feature from Enterprise, so I do really expect this to ship and get out of Alpha sooner rather than later and this time, I mean it. Prove that f is one-to-one on D How to clear current “read-only” state on a USB flash drive I setup with Rufus? Three weeks ago I used  2.2 to install Windows 10 on my machine, and it has write-protected my flash drive. I’ve tried diskpart:  diskpart att disk clear readonly  clean create partition primary format fs=fat32 quick   And it kinda worked, it removed the image off the USB, but now it’s showing:  Current Read-only State : Yes Read-only  : No Boot Disk  : No Pagefile Disk  : No Hibernation File Disk  : No Crashdump Disk  : No Clustered Disk  : No   And I can’t format it or write on it.    The drive is a a Kingston DataTraveler G4 32GB model, without physical switches. How would I restore it back to normal (rw) state? Integral $\int\csc^3{x} \ dx$ How do you run your own code alongside Tkinter's event loop? My little brother is just getting into programming, and for his Science Fair project, he's doing a simulation of a flock of birds in the sky. He's gotten most of his code written, and it works nicely, but the birds need to move every moment.  Tkinter, however, hogs the time for its own event loop, and so his code won't run. Doing root.mainloop() runs, runs, and keeps running, and the only thing it runs is the event handlers.  Is there a way to have his code run alongside the mainloop (without multithreading, it's confusing and this should be kept simple), and if so, what is it?  Right now, he came up with an ugly hack, tying his move() function to &lt;b1-motion&gt;, so that as long as he holds the button down and wiggles the mouse, it works. But there's got to be a better way. Reverse Triangle Inequality in vector space I have already proved Triangle Inequality $\lVert v+w\rVert \le \lVert v \rVert+\lVert w \rVert$ in vector space $\mathbb{R}^n$. However, I'm having difficulties proving the Reverse Triangle Inequality in the vector space.  I have started with   $$\lVert v \rVert^2=v \cdot v-w\cdot w+w\cdot w \le \lVert v-w \rVert+\lVert w \rVert^2$$ $$\lVert w \rVert^2=w \cdot w-v\cdot v+v\cdot v \le \lVert w-v \rVert+\lVert v \rVert^2$$  based on the Triangle Inequality but I don't know if it is correct. If this is right, I think I can go on with proving it the same way I would the normal Reverse Triangle Inequality. How to change the default views of quad view? How do I change the TOP ortho view to BACK ortho view for my BACK image?   check out the pic I uploaded to see what I'm talking about. Is there a way to separate variables between multiple notebooks? Integral of $\sqrt{1-x^2}$ using integration by parts As I have seen in other posts, i.stack.imgur.com is blocked by numerous companies' firewalls including my own. I have started the process to get the restriction lifted but to increase the likelihood of it being granted, have only requested that i.stack.imgur.com be unblocked.  Staying within the context of SO, imgur and the hosting arrangement SO has with them, are there any other sub-domains/domains that I should be requesting be unblocked? i.e. p.stack.imgur.com or *.stack.imgur.com?  I'm not sure if images can still be embedded/hotlinked in posts from other image hosts or not but if they can I'm not interested in unblocking those hosts, just the addresses used by SO for imgur.  Cheers :) Positive operator has a positive spectrum? How to get product recommendations Possible Duplicate:          I have a question of the form "what companies provide service X?"  I checked meta, and apparently such questions are highly discouraged on all Stack Exchange sites. Which is fine, but it obviously raises the meta-question: Where can I ask my question?  (In particular, I know that there are people hanging out on Stack Overflow who have probably needed the same service, so if an answer exists, they possess it...)  Edit: I should perhaps point out that the service I'm looking for is rather specific and slightly obscure. Otherwise, yeah, this would be a 10-second exercise with Google. Calculation of pressure from flow rate of water Anybody kindly help me to find how to calculate pressure in bar from flow rate. I have a pipe and from that I am transferring water at a constant flow rate of 5ml/min. At this flow rate, with a 0.5 cm diameter pipe, what will be the pressure generated by water? The muffins were rock hard, what did I do wrong? Here is the recipe I used, I did not mix it for long, as that make the muffins very hard.   The muffins were very hard, and had a bad after taste and smell. I missed adding some oil, but what else could be the reason ?   Red Millet Flour, 50 g Whole Wheat flour, 50 g Toasted Oat Bran, 40g Whole Green Mung Beans - Sprouted, 100 g Domino - Light Brown Sugar 50g Baking Soda, 2 tsp Salt, 1 Tablespoon Liquid Egg White, 4 eggs 100% Whey (Vanilla), 75g Chobani - Greek Yogurt - 0% Vanilla, 5.3 oz (small packet) Carrots - Raw, 1 cup, grated Bananas - Raw, 1 cup, mashed White, all-purpose, enriched, bleached, 40 g   Also I wanted to try yeast instead of baking soda, but due to eggs and other veggies I cannot let is rise overnight (any ideas ?). I was trying to make good protein muffins which are an ideal breakfast, grab one with a glass of milk and done!   They run approximately 160 calories per muffin 25g carbs, 1g fat, 12g protein. These HDDs will be used mostly for backups and data-storage (pictures, movies) which aren't often read. The price difference is 1.5 Euros in the case of these two:   HDD Western Digital Caviar Green Power 500GB, 7200rpm, 32MB, SATA2 HDD Western Digital Caviar SE16 500GB, 7200rpm, 16MB, SATA2   The only difference is the buffer size (16MB vs. 32MB). Is the larger buffer size worth the extra money?