Open a GTK program as another user As thisuser, I go to shell and run $ su anotheruser. It asks for password and then switches the user. Then I run $ gedit anyfile. But now instead of opening gedit, it gives error:  No protocol specified (gedit:388): Gtk-WARNING **: cannot open display: :20.0   How do I get this running?  EDIT:  Output of ls -l "$XAUTHORITY" when run as anotheruser  -rw------- 1 thisuser thisuser 260 Mar 31 22:35 /home/thisuser/.Xauthority
Why should users never use normal sudo to start graphical applications? I've read  and am interested in this line:     You should never use normal sudo to start graphical applications as Root.   Why? What is the difference? Please provide a simple explanation, as I'm just a normal desktop user.
Why does this formulation of Choice not follow from the Comprehension Schema? Integral $\int\frac{dy}{(y^2 + ay + b)^{3/2}}$ Need the indefinite integral with $a,b$ constants. This is not a homework question. Need it for a physics problem. I am having some issues when rendering an image, my rendering screen is turning into grey even when making a full render. What am I doing wrong? I have searched the web a lot and could not find an answer that fits my situation. Here are two links that are quite contradictory:       My situation:  I've visited Portugal in December 2012 for 29 days on a Schengen visa valid from December 1st, 2012 to February 1st, 2013 for research purposes (I am a Ph.D. student). I want to visit Sweden from February 10th, 2013 to May 10th, 2013 (89 days). I have applied for a Schengen visa again (for research). How will the 90/180 rule work in my situation? Since I can't find any alternative to Linux'  elevation command, I have the following question:  How to define a PowerShell function which requires elevation? I mean UAC prompt.  Say, such function follows:  function system-check {     SFC /ScanNow }   System:  Windows 8.1 Pro 64-bit  PowerShell:   Major  Minor  Build  Revision -----  -----  -----  -------- 5      0      10586  117    EDIT1:  To be 100% understandable let me rephrase:   I run PowerShell as user I run the aforementioned function system-check I want the function to elevate in order to be able to execute the command; note, that I want the UAC prompt to appear A matrix $M$ that commutes with any matrix is of the form $M=\alpha I$ How can I customize different nodepart with different textures? My question is how can I customize hatch patterns(grid, vertical line, etc.) for different nodepart in a node?  The following is a failed try.  \documentclass[border=2mm,convert]{standalone} \usepackage{tikz} \usetikzlibrary{shapes.multipart,patterns}  \begin{document} \begin{tikzpicture} \node[rectangle split,rectangle split parts =2,rectangle split part fill={red!30,red!10}, rectangle split part pattern={grid,},draw]{one \nodepart{second}two}; \end{tikzpicture} \end{document} Connect MacBook Pro to two external monitors Is there a way to connect my MacBook Pro to two external monitors (either VGA or HDMI; no Thunderbolt) in such a way that the Mac screen serves as a third monitor?  What hardware do I need? What is the amplitude of a light wave? Referring to this question   I'm curious about what is a amplitude of a light wave. Especially for light from a thermic source. How to increase camera frames view area? The Camera view area is so small (see picture). How can I increase it? I need to write a Java Comparator class that compares Strings, however with one twist.  If the two strings it is comparing are the same at the beginning and end of the string are the same, and the middle part that differs is an integer, then compare based on the numeric values of those integers.  For example, I want the following strings to end up in order they're shown:   aaa bbb 3 ccc bbb 12 ccc ccc 11 ddd eee 3 ddd jpeg2000 eee eee 12 ddd jpeg2000 eee   As you can see, there might be other integers in the string, so I can't just use regular expressions to break out any integer.  I'm thinking of just walking the strings from the beginning until I find a bit that doesn't match, then walking in from the end until I find a bit that doesn't match, and then comparing the bit in the middle to the regular expression "[0-9]+", and if it compares, then doing a numeric comparison, otherwise doing a lexical comparison.  Is there a better way?  Update I don't think I can guarantee that the other numbers in the string, the ones that may match, don't have spaces around them, or that the ones that differ do have spaces. mail -s "subject" xxxxx@gmail.com &lt;test.html works, but only for plain text email.  What is the correct way to send HTML email using the Linux command mail? Please help me to draw the following diagram:  \begin{displaymath} \xymatrix{ H\ar[r]&amp;H .1={}_HI_Q\supset 1.Q&amp;Q\ar[l]_\epsilon^{\cong}  \\  &amp;R\ar[u]\ar[r]&amp;R\ar[u] } \end{displaymath} When should I start an LLC for my side work? I am doing quite a bit of sidework this year and wondering at what point would it be a good idea to "start a business" and bill through that. Why do objects sometimes fall on their own? Help me identify this insect from Bangladesh I have seen this insect flying literally everywhere in Dhaka city (Bangladesh) over the last two months. It's small -- around 1-1.5 inches long. It's not an agile flyer and can be easily grabbed by hand during flight. The following message keeps appearing on my Samsung Galaxy S4 phone screen about every three seconds  "Unfortunately, Google Play Services has stopped".    Is it actually a virus or it is a problem with the Google Play Service?  I have tried disabling the Google Play Service but the message keeps appearing.  I have Norton Mobile running on my phone to pick up on viruses and to alert me to any possible security issues and also Lookout. They haven't picked up anything.  Does anyone have any suggestions? The "Reputation &amp; Moderation" page on any site (/help/site-moderators) still refers to the company behind Stack Exchange as Stack Exchange and not Stack Overflow.     Moderators act as a liaison between the community and Stack Exchange the company.   Seeing as how the name change was recent, I'm not surprised this hasn't been caught yet, and I'm sure there are other instances of this around somewhere. If $-1&lt;x&lt;1$ show that $\lim\limits_{n \to \infty}{n\,x^n} = 0$. I don't have idea. I only prove that $n\,x^n$ is decreasing. Why does a vertical line have a SLOPE (steepness) of undefined? The curve shows :   x goes 1 to right  y goes up by 3   the SLOPE is defined as the ratio of rise to the step  SLOPE = rise/step = 3/1 = 3  Now that :   Horizontal line has SLOPE of 0. Vertical line has SLOPE of undefined.   It makes sense for me to imagine horizontal line has SLOPE of 0 since there is no rise at all. But why the vertical has SLOPE of undefined.?