User Mode Symbol for Bash Prompts I am trying to find the names/differences/what is the symbol called at the of the prompt provided at the entry line for Bash.  For example: user@user~$ what is the $ called, and why on some systems is user % not $? is that a setting that can be changed?  I am thinking about this from the perception of Cisco IOS, between > (user) to # privileged exec. The symbols serve a purpose there, so what purpose do they serve on a *Nix system?
Why is $ the default symbol for a user shell and # the default symbol for a root shell? Operating a standard bash shell on a server, the PS1 prompt defaults to ending in a $ for non-root users, and # for root.  IE:  ubuntu@server:~$ sudo su root@server:/home/ubuntu#   Why is this?
Do you have to want to hurt someone for the cruciatus curse to work? Let $A \times \emptyset = \{(x,y)| x\in A, y \in \emptyset \}$. We know there is no element in $\emptyset$. But how does it follow that $A \times \emptyset = \emptyset $? How widespread is the practice of delegating LoR writing to the applicant? At least two questions (, ) on this site indicate that in more than a few isolated cases at least, letters of recommendation are in fact written by the applicant and only signed off (or perhaps rephrased somewhat) by the recommender, who would actually be responsible for writing the letter.  Is there any evidence about the prevalence of this practice that goes beyond anecdotes? I realize that cross-country (cultural) difference may play a role. (Re?)Install Ubuntu on a Dell laptop that had Ubuntu preinstalled Improving how suggested edits are displayed in your activity history Issue 1: I find it a bit irritating that when I click the Improve button and further edit it, even if I mark it as helpful, only Community takes the credit for the approval. I know the topic itself will contain the link to the suggested edit, but my activity history only says that I made an edit, and not approved a suggested edit. The same holds true for marking one as unhelpful. The activity history should say I rejected an edit, and then made an additional edit. I know it's not often, but sometimes I do try to go back to a suggested edit I've rejected, but when I improved and rejected, it's not traceable for me as it doesn't show in my history or in the question's revision history. So if I don't remember what user suggested it, it's lost to me.  This issue also plagues the  which are awarded for approving and rejecting suggested edits, which essentially you have done, you're just not receiving credit for it. I suggest that when I mark an edit as helpful or not helpful, both me and Community be listed as the approvers or rejecters, unless another user is already listed in the appropriate place.  Update: Here is  of the confusion this causes.  Update 2: Also, when improving a post and marking it as "not helpful", it would be nice to be able to  along with it.    Issue 2: Expanding off the idea that users need more notice for suggested edits that get rejected, the activity history page is much too useless when it comes to listing the suggested edits a user has made. Literally all it does is list them. A user still has to click through to each one in order to find out if it was approved or rejected, or even if it's still pending. Take, for example, this screen shot of the suggested edit history:    Is it really necessary to say I suggested a suggested edit? Really? Of course I suggested it, it's a suggested edit. This isn't !  A good way to fix this would be to change the second "suggested" word into one of: pending, approved, or rejected. This would be a quick way to tell which edits have been approved or rejected and which ones are still pending. Users would be able to target out rejected edits and review them for the reasons. Something like this: Position of "only" in “We 𝒐𝒏𝒍𝒚 have two possibilities” Is there any difference in meaning between the three following sentences?   We only have two possibilities. We have only two possibilities. We have two possibilities only.   I have already read  and I know that the position of only and the emphasis (written or oral) may change the meaning of some sentences, but I am not sure if it does here.  Note: It is clear that “only we have two possibilities” has a different meaning. My question is restricted to the sentences I’ve listed above. Children’s books, one in space setting, the other in a jungle When I was little I remember getting these two books from the library.  Both books were paperback and flimsy.  The pages were wide.  Each book had full page illustrations with puzzles and mazes in them, but it was like you were immersed in this setting completely.  They were also like choose-your-own adventure books, but only in the way that you go through the book in a different order based on your results in the puzzles/games.    For example, there is a bridge to cross, or you can take this path.  If you choose to cross the bridge you go to page x.  On page x you have to pretend to cross the bridge but some planks are broken.  You can't skip more than a certain number of planks, but you also cannot "step" on a broken plank.  One book was in a jungle setting with rope bridges, alligators, quick sand, etc. The other was in space, with all kinds of aliens and weird stuff.  I have faint memories of these books but I REALLY want to track them down because I remember loving them. How do I capture the moon and its surrounding context? I wanted to photograph the full moon against a beautiful deep blue sky. I ended up with blown-out highlights of the moon:    So I switched to spot metering and captured the moon, losing the blue sky in the process:    I want a single photo that shows both the moon and the surrounding context (in this case, the blue sky). Doing an exposure fusion in Photomatix Essentials did not help:    Nor did HDR fusion (again in Photomatix):    Notice that the detail in the moon was lost in both cases, and the sky was also messed up in both cases: exposure fusion lost the beautiful blue color, while HDR created more texture than was actually present in the sky. I toggled Photomatix's option to remove ghosts, but that didn't help, either.  How do I photograph the moon together with its surrounding context (in this case, the blue sky, but in other cases, a tree, buildings, etc) without blowing highlights or shadows? I'm using a Sony NEX-5R, with the longest focal length lens I have, and with manual focus when needed.  Thinking I should fuse the photos manually, I tried opening the images as layers in Acorn, with the darker photo on top and with opacity set to 50%, and tried all 15 - 20 blending modes (normal, dodge, lighter, darker, multiply and so on), but none of them seemed to work. I'm afraid I don't know enough to use layers effectively. What blending mode and opacity and order of layers should I use for this task?  I don't have Photoshop, but do have Lightroom 5, Acorn and Nik Collection.  (In case you are about to recommend software, please note my requirements: I use a Mac, I would be willing to pay $20-30, and I don't want to use command-line software.) Here's a module with castellated pads attached to an eval board:  (source: ) Looking closely at the wires interfacing with the castellated pads, they're clearly soldered to the eval board. However, they don't look like they're soldered to the module, but rather they're being pressed against the pads with the tension in the wire. It also looks like the free end of the loops are protruding down into a channel cut in the PCB. Do these kind of connectors/metal loops have a name? How to Recover truncate table in MySQL? How to backup symbolic link paths? Why should I avoid multiple inheritance in C++? Is it a good concept to use multiple inheritance or can I do other things instead? New breaker and panel: What's the brown goo where they connect? How to export variable for use with sudo? On Slackware, using sbopkg permits one to build a package from source. Repos is not big as Debian, but it's nice.  Some software can use environment variables, for example on the VICE c64 emulator, if the variable FFMPEG is set to yes, it will enable ffmpeg recording the emulator.  I tried to use  $ export FFMPEG=yes; sudo sbopkg -B -i vice   but ffmpeg is disabled.  Instead I had to use  $ su - $ export FFMPEG=yes $ sbopkg -B -i vice   which works.  How to use environment variables with sudo? Assign multiple keyboard shortcuts for one action Can magnetic fields be "blocked"? For example, in the game, TitanFall, a robot stop bullets with ( presumably ) a magnetic shield.  I wish to calculate the magnetic force required to stop a bullet within a few microseconds.  But the problem I have is that my entire electronic system or the vehicle ( most likely even a building ) will be subjected to massive fields most likely destroying it as well.  Does any know of a way to "block" or divert the field around my vehicle? Is it even possible? My knowledge in magnetic fields are quite limited at this time. Why does the base of this slinky not fall immediately to gravity? My guess is tension in the springs is a force > mass*gravity but even then it is dumbfounding. Is there a built-in method to compare collections? I would like to compare the contents of a couple of collections in my Equals method.  I have a Dictionary and an IList.  Is there a built-in method to do this?  Edited: I want to compare two Dictionaries and two ILists, so I think what equality means is clear - if the two dictionaries contain the same keys mapped to the same values, then they're equal. Proof of a formula involving Euler's totient function: $\varphi (mn) = \varphi (m) \varphi (n) \cdot \frac{d}{\varphi (d)}$ I use the highlight mode in vim to copy a few characters.  I then want to paste more than once.  My current technique does not work well.  Sample text: Linux Solaris Irix HP-UX  Suppose I want to copy the word Linux, then paste over Solaris and Irix.   Place cursor at L in Linux Command v (for visual hilite), then e (for end-of-word), then y (for yank/copy) Now Linux is on my "vim clipboard" Move cursor to S in Solaris (first instance) Command v (for visual hilite), then e (for end-of-word), then p (for paste) Text is now: Linux Linux Irix HP-UX, but now Solaris is on my "vim clipboard" Move cursor to I in Irix (second instance) Command v (for visual hilite), then e (for end-of-word), then p (for paste) Text is now: Linux Linux Solaris HP-UX which is not what I expected.   I resort to using highlite/paste with the mouse (via X Terminal).  Surely, I can do this better.  How?