I have looked at the questions and answer here at U&amp;L but I still cannot get my default group to change from a user.  [red@ws-red-l ~]$ whoami red [red@ws-red-l ~]$ groups yellow green [red@ws-red-l ~]$ sudo usermod -g green red usermod: no changes [red@ws-red-l ~]$ sudo usermod -G green red [red@ws-red-l ~]$ groups yellow green [red@ws-red-l ~]$ touch file [red@ws-red-l ~]$ ls -l file -rw-r--r-- 1 red yellow 0 Feb 18 13:51 file   I would prefer if red did not belong to group yellow so when I do a touch file the group of the file would be green.  What am I doing wrong here?
I changed permissions of a file (chmod g+w testfile) and running ls -l testfile gives:  -rwxrwxr-x 1 user1 user1 0 2011-01-24 20:36 testfile   I then added a user to that group ("/etc/group" has user1:x:1000:user2 line), but am failing to edit that file as user2. Why is this so?
The Winter Bash is back and the hats are listed below.  As always, there are only two answers: one for the secret hats, and one for the regular hats. The secret hat list will be updated as we learn them.  Only edit the secret hat answer with definitive and correct triggers. This is not the place to post guesses.    If you'd like to discuss Winter Bash, hats or just have a question about the WB please come over to the .  Please keep the comments here clean. As always comments are not meant for discussion, conversation, "I just got hat X", etc use the  for that (the remaining meta mods will periodically clean the comments). I know you are excited you just got a secret hat, but please instead of posting a comment come over to the  and tell us all there.  Provided that "It's important to know your history... in more ways than one"  again this year, here are the hats from prior years: Increase partition size on which Ubuntu is installed? I have Ubuntu installed on a drive. The problem is it is running low on disk space. This is installed on vmware. I expanded the virtual drive and booted into ubuntu. But when I opened gparted(sudo gparted), the move/resize option is unavailable. This is the partition Ubuntu is installed on, but I need to resize it. Any ideas? I am comfortable using command line I'm studying measure theory and two question came to my mind:        If $f:\mathbb{R}\to\mathbb{R}$ is monotone and $B\subseteq\mathbb{R}$ is borel, is the image $f(B)$ borel?   If $f:\mathbb{R}\to\mathbb{R}$ is a monotone function (say, non-decreasing), does there exist a sequence of continuous functions $f_n:\mathbb{R}\to\mathbb{R}$ converging pointwise to $f$?      Here's the motivation for those questions: Let $(X,M)$ and $(Y,N)$ be measure spaces.   It's known that if $\mu$ is a measure on $(X,M)$ and $f:X\to Y$ is measure, then we have the pushforward measure $f_*\mu(A)=\mu(f^{-1}(A))$ on $(Y,N)$. What if we were to define a "pullback measure"? Given a function $f:X\to Y$ such that $f(M)\subseteq N$ (i.e. $f$ maps measurable sets to measurable sets) and a measure $\nu$ on $N$, the natural formula would be $f^*\nu(A)=\nu(f(A))$. So we ask if is there a good amount of functions which map measurable sets to measurable sets in $\mathbb{R}$, and monotone functions seem like good candidates (for strictly monotone, continuous functions, the result is valid and there are several answers on the web). If this were true, maybe we could use some convergence argument to solve the problem above. Can I enable AHCI after installing Windows 7 in a SATA drive that was on IDE mode? Java generics super keyword I need to define a new command to create a squiggle arrow with some text on it. Something similar to what \xrightarrow command produces but with wiggly arrows as in \rightsquigarrow. The length of the arrow should automatically be adjusted to fit the text above it and I do not know how to handle this part in TikZ. Any ideas would be much appreciated. I have a series of ranges with start dates and end dates. I want to check to see if a date is within that range.  Date.before() and Date.after() seem to be a little awkward to use. What I really need is something like this pseudocode:  boolean isWithinRange(Date testDate) {     return testDate &gt;= startDate &amp;&amp; testDate &lt;= endDate; }   Not sure if it's relevant, but the dates I'm pulling from the database have timestamps. Proof of triangle inequality So when we view reputation, there is graph view. However, it seems to be off by a day. Here's what I mean:   I'm sure 70 + 20 + 15 is not 15. Its 105, which is what we see below:   And 40 + 10 is NOT 105, unless you did  :)     Anyways 40 + 10 is 50:   So yeah. Did you do what that post on codegolf says? Devs better fix that :) Drive from US to Canada with a dog Suppose you have an object with zero for the value of all the derivatives of position. In order to get the object moving you would need to increase the value of the velocity from zero to some finite value. A change is velocity is acceleration, so the value of the acceleration would have to increase from zero to some value. You would also need to increase the jerk from zero to some value to have a change in acceleration.  Is there an infinite series of higher derivatives of position for this to work? Or am I missing something? What apps to sync movie subtitles easily are available for Ubuntu? I have a subtitle file that is about 3 to 4 seconds behind. What tools can I use to automatically move all the times in the subtitle file so they are correct with the time of the movie? Something that I can for example just add the time I want to add and it will add this time to the synced times in the subtitle files without having to edit each line individually. Why's &quot;what's up&quot; used as greeting among young people? It sounds like asking &quot;what is up there&quot;?  A: What's up? B: The sky. How to access the Index Of A Generic.List By Reflection? ok, ive a class and i pass an object as property.  the object that i pass is a List&lt;X&gt;  in my class im trying to access the Object index by reflection BUT I CAN'T!!!   Example:  this class works i just wrote down the part i want to show you and i need help.  class MyClass {     private object _recordSet;     public object RecordSet     {         get { return _recordSet; }         set { _recordSet = value; }     }      public string Draw()     {         system.reflection.Assembly asem = system.reflection.Assembly.getAssembly(_dataSource.GetType());          object instance;          instance = asem.CreateInstance(_dataSource.GetType().UnderlyingSystemType.FullName);          //to access de Count of my List         int recordcount = int.Parse(_dataSource.GetType().GetProperty("Count").GetValue(_dataSource,null));          //i need to do a          for(int cont = 0; cont &lt; recordCount; cont++)         {             _dataSource[cont].Name; // &lt;-- THIS PART IS NOT WORKING!!! because i cant access the Index Directly.... WHAT TO DO!! ???         }     } } How do I recover the default version of some configuration file? By accident, I messed up a configuration file. How do I recover the default version without reinstalling or affecting other things? Choosing variables to include in a multiple linear regression model I have a MacBook Pro Retina (2015). After updating to OS Mojave, Bluetooth has stopped working. I get an error message that "No Bluetooth Hardware Found".  I have already tried to do the following:   Go to the /Library/Preferences and delete the com.apple.Bluetooth.plist file Successfully resetting SMC. (pressing Shift+ctrl+alt + power button) Removing the Bluetooth icon from the menu bar    None of the above solutions has worked for me. Why do we age? or Do we have a theory of senescence? There seem to be a number of ideas about why we age. Hypotheses include the gradual accumulation of cell metabolic products affecting organism function and the reduction of  during cell division. My hand-wavey idea would be "wear and tear".  Are we anywhere near a consensus theory of senescence? How to determine if Javascript object is an event? Posting to friends' wall with Graph API via 'feed' connection failing since Feb 6th 2013