Why is this margin here?
How to horizontally center an element
Disable storage of invisible files "._" on my cfs or smb network storage I use OS X Mavericks and have some company storage drives mounted (using smb or cfs). (smb://username@address.path.toserver.com/directory/data). When I work with files on the drive or copy files to the drive, some hidden files are created. Most of these files start with dot-dash ._ and then the filename of the original file, like:  ._test001.png ._test002.png ._test003.png   And most of the times, the famous ._.DS_Store and .DS_Store are also there.  On my Mac, these . dot items are invisible, but my windows colleagues do see these files. How can I prevent OS X from making these strange invisible files?  On  (and other internet sources) you can find a 'defaults write' to disable the creation of .DS_Store files on your network drives. But this does not work in Mavericks:  defaults write com.apple.desktopservices DSDontWriteNetworkStores -bool true   For now I use this oneliner, but doing a rm -rf does feel wrong in this case.  find . -type f -name "._*" -exec rm "{}" \;   Edit: I don't want to delete the files or exclude them from copying. I want them not to be created in the first place.  Edit: I prefer a 'native' OS X solution over third party apps.  Edit: This questions has two answers, one for the ._ files and one for the .DS_Store files. The bounty is rewarded for dot_clean, this native command line app cleans all ._ files. Unfortunately is does not clear the .DS_Store files, this can effectively be done with Asepsis. Asepsis stores .DS_Stores in a fixed location, and not in the folder itself. How can I make an object show up on different layers Currently, I'm trying to get a method in Python to return a list of zero, one, or two strings to plug into a string formatter, and then pass them to the string method. My code looks something like this:  class PairEvaluator(HandEvaluator):   def returnArbitrary(self):     return ('ace', 'king')  pe = PairEvaluator() cards = pe.returnArbitrary() print('Two pair, {0}s and {1}s'.format(cards))   When I try to run this code, the compiler gives an IndexError: tuple index out of range. How should I structure my return value to pass it as an argument to .format()? Todo comments:Not include and left align? missing $ inserted error for equation I get the missing $ inserted error for the following code:  \begin{equation}  C = $ \frac{2}{\omega^2N^2\mu\pia} $  \end{equation}   I have tried out different changes based on Googling for this error, but nothing seems to help. Any suggestions would be appreciated. Is convex hull of a finite set of points in $\mathbb R^2$ closed? Is the convex hull  of a finite set of points in $\mathbb R^2$ closed? Intuitively, yes. But not sure how to show that. Thanks! Image capture opens after iPhone is connected Everytime I connect my iPhone to my laptop, Image Capture opens. How to I stop it? I just need to use iTunes, not Image Capture. "Firstly" or "first"? What's a good phrase for "refining a process which is hopelessly broken"? I'm looking for a turn of phrase to describe a situation where the powers that be wish to continue making small improvements to a process which, due to deep-rooted flaws, will never be close to accurate.  I'm working on a process for estimating the states of business objects, and there's interest in fixing some edge cases which have been noticed.  This could be worthwhile, but because of missing data we're already making heroic guesses.  So if implemented, we might get from 80.0 to 80.1% accuracy.  If we were at 99.5%, I'd be happy to get it to 99.6%, but in the current situation it doesn't seem productive.  We have some CS people on E.SE; what would you call it when someone wants to optimize a two-second process to load data, though once loaded it will be chewed on by an inefficient algorithm for hours?  Something like "bailing the ocean" or "fixing a leaky faucet in a burning building" is close to what I have in mind.  There's also "rearranging deck chairs on the Titanic," but that carries an implication that the changes are wholly useless, and that events are coming to a head. I own a Nikon D40X and just the kit lens and I'm considering buying either a macro lens or some extension tubes.  I don't necessarily want to do true 1:1 macro, just some close ups of bugs, fungi and flowers. I'm trying to set up a way for me to just type newjournal, and a new journal entry named year-month-date-time.txt is created in a year subdirectory in ~/documents/journals.   I've got it set up as an alias using the following:  alias newjournal='nano /home/username/documents/journals/'$(date +%Y)'/'$(date +%F-%k%M).txt''   So the year subfolder resolves correctly, and seemingly so does the first half of the date command. Tried appending the alias with sudo, didn't help.  Issue: For some reason, when I do this command the time value (%k) resolves to a few minutes ago... or maybe the last time nano ran this filename, maybe it's called an old buffer?   When I logoff it makes the correct file, then I save, wait a few minutes and try again, and it edits the old file instead of making a new one. Even if I remove the old file, it creates a new file with the old filename (incorrect time).  Here's a screenshot of what I'm trying to explain. Here I create a newjournal, save in nano within a second or two of executing the command, print the correct date/time, list the file that was created. Note the incorrect filename time (1249, as apposed to 13:11):    Anyways, it might be something simple, but I've tried different methods in the alias, such as putting double quotes around the whole thing and escaping properly, single quoting, escaping and spacing, etc.  Thanks for the read/help. Ubuntu 16.04 server.  EDIT: Here's the final alias that worked:  alias newjournal='nano /home/user/journals/"$(date +%Y)"/"$(date +%F-%H%M).txt"'   Needed to double quote the date commands inside the overall single-quoted alias. Spacing before and after section titles Perl - Package/Module Issues What is an example of perfect collinearity in terms of the design matrix $X$?  I would like an example where $\hat \beta =  (X'X)^{-1}X'Y$ can't be estimated because $(X'X)$ is not invertible. How do I get the form id of my form? I've just begun to make my modules and I'm at a standstill. I got this code from someone else and am trying to customize it:  function hook_form_alter(&amp;$form, &amp;$form_state, $form_id) {   if ($form_id == 'the form id for the node form') {     $form['#submit'][] = 'my_custom_submit_handler';   } } Game states & passing data between scenes Why does Stack Exchange ask for a reload on successful automatic login? I'm looking for an answer considering both technical limitations and user experience.   Does it need a reload from a technical standpoint? Time-ordered operator in Srednicki , "Note that the operators are in time order...we can insert $T$ without changing anything". This I agree with. But then on the next paragraph he states "The time order operator $T$, moves all...where they annihilate...". How correct is this paragraph? Is equation (5.14) always valid? Is equation (5.14) the reason why the time-ordering symbol $T$ appears all over the place in QFT?  The equations I'm referring to are (braket package available?):   $$\langle f|i\rangle = \langle0|~a_{1'}(+\infty)a_{2'}(+\infty)a_{1}^\dagger(-\infty)a_{2}^\dagger(-\infty)~|0\rangle \tag{5.13} $$  and since time goes from right to left inside the braket we put the $T$-symbol  $$\langle f|i\rangle = \langle 0|T ~a_{1'}(+\infty)a_{2'}(+\infty)a_{1}^\dagger(-\infty)a_{2}^\dagger(-\infty)~|0\rangle \tag{5.14} $$   without changing anything.   After this, the $T$-symbol appears everywhere! Find the derived subgroup of $A_4$ Find the derived subgroup of $A_4$.   Since it is $A_4$, for a permutation $\sigma$ to be in $A_4$, $\sigma$ must have a cycle structure of $2$ cycles. Therefore, $\sigma=(ab)(cd)$.  The commutator of such elements, would be obviously another permutation of $2$-cycle (of length $2$).  Does it mean that $A'_4=A_4$? Filling in new field in attribute table based on values of another field in ArcGIS Desktop? I have added a new field (Category) in an attribute table of a shapefile and I would like to fill it with numbers, 0 or 1, based on the numbers of another field (Calorific value) of the same attribute table.   That means that if the Calorific value is higher than 15, then I would like to fill in the corresponding cells of the (new) Category field with 1. If the Calorific value is less than 15, then the rest cells of the (new) Category field to be filled in with the number 0.   Is there a way to do this automatically rather than manually?