I have been trying to get a program called "passenger-memory-stats" to run as the super user. The program is installed in the following directory: /usr/local/rvm/rubies/ruby-1.9.3-p327/bin/ruby . I know this because i installed phusion passenger using ruby gems:  $ gem env RubyGems Environment:   - RUBYGEMS VERSION: 1.8.24   - RUBY VERSION: 1.9.3 (2012-11-10 patchlevel 327) [x86_64-linux]   - INSTALLATION DIRECTORY: /usr/local/rvm/gems/ruby-1.9.3-p327   - RUBY EXECUTABLE: /usr/local/rvm/rubies/ruby-1.9.3-p327/bin/ruby   - EXECUTABLE DIRECTORY: /usr/local/rvm/gems/ruby-1.9.3-p327/bin   - RUBYGEMS PLATFORMS:     - ruby     - x86_64-linux   - GEM PATHS:      - /usr/local/rvm/gems/ruby-1.9.3-p327      - /usr/local/rvm/gems/ruby-1.9.3-p327@global   - GEM CONFIGURATION:      - :update_sources =&gt; true      - :verbose =&gt; true      - :benchmark =&gt; false      - :backtrace =&gt; false      - :bulk_threshold =&gt; 1000   - REMOTE SOURCES:      - http://rubygems.org/  /usr/local/rvm/gems/ruby-1.9.3-p327/bin $ ls -l | grep passenger-memory-stats -rwxr-xr-x 1 guarddoggps rvm 416 Dec 14  2012 passenger-memory-stats   So obviously the program is there. I then add it to the root user's PATH environment variable:  $ sudo su export PATH=$PATH:/usr/local/rvm/gems/ruby-1.9.3-p327/bin echo $PATH /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/usr/local/rvm/gems/ruby-1.9.3-p327/bin   So now it has been added to PATH environment variable. I exit from sudo user to my regular user with sudo privilege and I run the following:  $ sudo passenger-memory-stats sudo: passenger-memory-stats: command not found sudo -E passenger-memory-stats sudo: passenger-memory-stats: command not found   Why does it tell me command is not found? Didn't I add it to my sudo user's path? So I check:   sudo su  echo $PATH /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games   ANd to my surprise, the directory is no longer in the path. What happened?
for normal user I get :     /usr/lib/lightdm/lightdm:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/home/monty/google_appengine   which is actually the content of /etc/environment  For root I get:     /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin   what's the reason behind this and which file contains this line?
My wife is an Indian national with an Indian passport. She holds an indefinite leave to remain in the UK (permanent residence card). Does she need to apply for a Schengen visa before travelling to France or any other Schengen countries? I want to say:  Please, check out our handbook/knowledge base.  ...but it can be interpreted in two ways:  Please, check out our (handbook/knowledge) base. — as if there is a &quot;handbook base&quot; and a knowledge base. Please, check out our handbook/(knowledge base). — the meaning I'm after.  I thought that maybe I should put spaces around the slash to better separate the two choices:  Please, check out our handbook / knowledge base.  ...but I'm not sure that does it. I checked out  on the topic and it didn't answer my question.  Is it possible to convey the right meaning with a slash, or should I just avoid it altogether? Support for OpenID ended on July 25, 2018 Determining true mean from noisy observations I have a large set of data points of the form (mean, stdev). I wish to reduce this to a single (better) mean, and a (hopefully) smaller standard deviation.  Clearly I could simply compute $\frac{\sum data_{mean}}{N}$, however this does not take in to account the fact that some of the data points are significantly more accurate than others.  To put it simply, I wish to preform a weighted average of these data points, but do not know what the weighting function should be in terms of the standard deviation. Edit Mail rules manually How is my laptop ram running in dual channel? Proving $\, a^b = (a\bmod n)^b\, \pmod{\!n}\ $ [Congruence Power Rule] I am working on a problem I am pretty close to solving but I can't figure out the last part. I used some algebraic manipluation to break the problem down. The problem is:     Show that the following congruence is true      a^b = ((a mod n)^b) (mod n)      for any positive integers a, b, and n.      Hint: Number a can be written as a = q*n + r, where q = floor brackets a/n, and r = a mod n.   My attempt it:     (q*n +r)^b = ((a mod n)^b) * (mod n)      (q*n)^b + (a mod n)^b = ((a mod n) ^b) * (mod n)      (a)^b -(r)^b = ((a mod n) ^b) * (mod n)      (a)^b = modn  ----> divided by ((a mod n)^b)   Am I doing this correctly and if so how can I prove this is true? Is there a trick I am missing? I think that by simplifying it further I would just keep going in a loop.  Thanks! The Windows 10 April 2018 Update includes a new feature called Timeline which tacks the activities and allows you to see what you have done earlier, sends it to Microsoft servers, so that you can resume work on a 2nd device, which is connected to the same Microsoft account when you press the Tasks View button in the taskbar:    How can I disable the Timeline because I don't want that my activity gets tracked? Let $R$ be a commutative ring with identity, and $S$ a multiplicative subset of $R$ not containing $0$. Which step in my reasoning is wrong?   Every element of $S$ is a unit in $S^{-1}R$. Every element of $S$ that's a zero divisor in $R$ is a zero divisor in $S^{-1}R$. But zero divisors can't be units. Therefore it's not possible to localize $R$ at $S$. How can you describe someone who gives up too easily? Divergence of $\frac{ \hat {\bf r}}{r^2} \equiv \frac{{\bf r}}{r^3}$, what is the 'paradox'? What is the best program for image optimizing for the web? What programs besides Photoshop are good for saving and optimizing images for web? Can we make a Vpn server run on Android? Can we make a Vpn server run on Android. Can applications do this? If yes, which protocols are supported and is this a good idea to use such apps? If not, what are some issues that we may face? How to select lenses for outdoor sports photography? I would like to get into sports photography, and would probably want a better telephoto lens so I can get better close up shots.  What other factors should I keep in mind as I make my choice? Does IS (or VR) matter?  What is a good focal length?  I'll probably be shooting mostly little league baseball/softball, church softball leagues, and kids soccer. Recently I answered two questions on SO: The  is a completely trivial answer to a really basic question (kind of "read the manual and follow the one liner example there"). On the other hand, my  is a much more complicated answer that requires much more specialized knowledge of a very specific domain (happens to be related to my PhD research).  Clearly, the first answer could have been given by many SO users - I just happened to be the first to pick up the glove on this question. However, this is not the case for the second answer.  In contrast, when it comes to reputation - the first answer instantly got upvoted (everyone can relate to a simple question/answer), while the second one - I don't believe it will get much upvotes...  So, life isn't fair: for the one answer that really very few people could provide (the second answer) and is much harder to find and get -- is not rewarded, while the trivial answer is rewarded fast and strong...  How can we amend this? How can we encourage rare and specialized answers for difficult and deep questions?  Do we want SO to turn into a pool of trivial and superficial questions?    Update: Thanks to many meta-users who took the time to read through this question and ponder its implication, both answers I used as examples got exposed far beyond their fair-share. So, despite the fact that my original claim that the specialized answer get less reps is no longer valid, this does not change fact that in general my claim is stil valid: specialized answers requiring expert knowledge will recieve less attention at first.    Bottom line: (following my wish to have some sort of ). Indeed it sometimes seems like life isn't fair, but this is only in the short term. In the long run high quality answers do get their proper credit and exposure and their fair share of reputation. The reputation system of SO works quite well balancing and accounting for many factors and parameters. It would require a really strong argument backed up with serious research to change this mechanism.   Thank you all for the lively discussion and for showing me that life is fair after all. My Young's slits experiment doesn’t work. I mean I tried to see wave effect of light but I didn’t see any thing expect particles! I’ve sent you a pic of my laser and a short video of the experiment. Is there any problem you think? A positional number system for enumerating fixed-size subsets? Many combinatorial objects have some associated positional number system.  For example, the subsets of a (finite) set S can be listed off by observing the bits of all $|S|$-bit numbers, treating the 1s and 0s as indicators for whether to pick a particular element or not.  Permutations of a finite set S can be found by examining the  representations of the first $|S|!$ natural numbers.  Is there an analogous positional number system for encoding k-element subsets of an n-element set?  Thanks! Equivalent of cURL for Ruby? Proving set theory question I need to prove the following letting A and B be subsets of a universal set U. $$A\cup B = U \iff A^c\subset B$$ It just isn't straight forward to me. C# Compiler should give warning but doesn't?