Following on from a reinstall of ubuntu desktop sudo apt install ubuntu-desktop to fix a previous issue with not booting.  and then a reinstall of google chrome  sudo apt remove google-chrome-stable  I got the following output:  Reading package lists... Done Building dependency tree        Reading state information... Done Package 'google-chrome-stable' is not installed, so not removed The following packages were automatically installed and are no longer required:   gconf-service gconf-service-backend gconf2 gconf2-common gnome-panel-data gnome-shell-pomodoro-data gparted-common intltool   libaacs0 libaom0 libaribb24-0 libass9 libavutil56 libbdplus0 libbluray2 libbs2b0 libcodec2-0.9 libegl1-mesa libflite1   libgconf-2-4 libgme0 libgsm1 liblilv-0-0 libmusicbrainz5-2 libmusicbrainz5cc2v5 libmysofa1 libnorm1 libnuma1 libopenmpt0   libpaps0 libpgm-5.2-0 libpostproc55 libpython2-stdlib libpython2.7-minimal libpython2.7-stdlib librubberband2 libserd-0-0   libshine3 libsnappy1v5 libsord-0-0 libsratom-0-0 libssh-gcrypt-4 libswresample3 libswscale5 libvdpau1 libvidstab1.1   libvo-amrwbenc0 libwxbase3.0-0v5 libx265-179 libxcb-xtest0 libxnvctrl0 libxvidcore4 libzmq5 libzvbi-common libzvbi0   mesa-vdpau-drivers paps python-gobject-2 python2 python2-minimal python2.7 python2.7-minimal python3-distutils-extra   python3-levenshtein python3-pyinotify python3-websocket vdpau-driver-all Use 'sudo apt autoremove' to remove them. 0 to upgrade, 0 to newly install, 0 to remove and 5 not to upgrade.   And running sudo apt autoremove gives a warning about removing these packages      The following packages will be REMOVED ...   And the list of packages again. My question is is this safe to run, are these packages neccessary
I was compiling a tool called Rejoystick so I installed a few packages and dependencies. But now I don't need it any more so I removed those packages. Running apt-get shows that I have some packages that are automatically installed and are no longer needed.   But I have a bad experience with apt-get autoremove. It broke my desktop environment when I uninstalled wine some time ago. Luckily, I had a clonezilla partition backup then, but this time, I don't have a backup. So I'm cautious. Running apt-get shows these packages are orphaned     gir1.2-gtk-2.0 libasound2-dev libavahi-client-dev libavahi-common-dev   libcaca-dev libcairo-script-interpreter2 libdbus-1-dev libdrm-dev   libexpat1-dev libfontconfig1-dev libfreetype6-dev libgl1-mesa-dev   libglu1-mesa-dev libharfbuzz-dev libharfbuzz-gobject0 libice-dev   libpcre3-dev libpcrecpp0 libpixman-1-dev libpng12-dev libpthread-stubs0-dev   libslang2-dev libsm-dev libx11-dev libx11-doc libx11-xcb-dev libxau-dev   libxcb-dri2-0-dev libxcb-dri3-dev libxcb-glx0-dev libxcb-present-dev   libxcb-randr0-dev libxcb-render0-dev libxcb-shape0-dev libxcb-shm0-dev   libxcb-sync-dev libxcb-xfixes0-dev libxcb1-dev libxcomposite-dev   libxcursor-dev libxdamage-dev libxdmcp-dev libxext-dev libxfixes-dev   libxft-dev libxi-dev libxinerama-dev libxrandr-dev libxrender-dev   libxshmfence-dev libxxf86vm-dev mesa-common-dev x11proto-composite-dev   x11proto-core-dev x11proto-damage-dev x11proto-dri2-dev x11proto-fixes-dev   x11proto-gl-dev x11proto-input-dev x11proto-kb-dev x11proto-randr-dev   x11proto-record-dev x11proto-render-dev x11proto-xext-dev   x11proto-xf86vidmode-dev x11proto-xinerama-dev xorg-sgml-doctools xtrans-dev   zlib1g-dev   I'm not sure if I should run apt-get autoremove. I was searching details related to each of these packages so that I can understand which ones are needed but they all seem important e.g.     gir1.2-gtk-2.0    I have Cinnamon, GNOME and Unity installed, I think apt-get autoremove will break something. Any help will be appreciated.   Thanks for reading.
Removing the Bracket from the First Line of bmatrix How can I write a matrix with a header line that is not bracketed? I have used the following code to produce the results below. In addition of being ugly, it is impractical when I need to align the first row, n1, ..., n6 with the matrix columns.  \documentclass{book}  \usepackage{amsmath}    \begin{document}    \[ \ \ \ \ \ \ \ n_1\ \ \ \ \ \ \ \ n_2\ \ \ \ n_3\ \ \ \ \ \ \ \ \ n_4\ \ \ \ n_5\ \ \ \ n_6\]     \[ \begin{bmatrix}         1 &amp; -1 &amp; 0 &amp; 0 &amp; 0 &amp; 1\\         0.960 &amp; -0.977 &amp; 0 &amp; 0 &amp; 0 &amp; 0.983\\         0 &amp; 1 &amp; -1 &amp; -1 &amp; 0 &amp; 0\\         0 &amp; 0.977 &amp; 0 &amp; -0.983 &amp; 0 &amp; 0\\         0 &amp; 0 &amp; 0 &amp; 1 &amp; -1 &amp; -1\\         0 &amp; 0 &amp; 0 &amp; 0 &amp; 0 &amp; 1\\        \end{bmatrix}        \begin{bmatrix}n_1\\n_2\\n_3\\n_4\\n_5\\n_6\end{bmatrix} =        \begin{bmatrix}0 \\ 0 \\ 0 \\ 0 \\ 0 \\ 100\end{bmatrix} \]  \end{document} I was trying to solve internet problems, and seem to have made things worse: Now when I start the computer it gets stuck on "Booting system without full network configuration".   Does anyone know how to make it unstuck?   Alternatively: It got messed up when I changed the contents of /etc/network/interfaces, so presumably would work again if I changed it back. How can I edit this file during boot?   I'm using Ubuntu 12.10. How to use find command to search for multiple extensions I can get all jpg images by using:    find . -name "*.jpg"     But how can I add png files to the results as well? Rigor in quantum field theory Deriving the inverse of a 2x2 matrix How do I define custom web.config sections with potential child elements and attributes for the properties? The web applications I develop often require co-dependent configuration settings and there are also settings that have to change as we move between each of our environments. All our settings are currently simple key-value pairs but it would be useful to create custom config sections so that it is obvious when two values need to change together or when the settings need to change for an environment. What's the best way to create custom config sections and are there any special considerations to make when retrieving the values? Why is SQL Server consuming more server memory? Is there a way to buy SO reputation? Why are airline passengers asked to lift up window shades during takeoff and landing? I have always wondered why the windows shades have to be raised during take off and landing. I can't think of any safety issues by having a closed window. I've always wondered why the number of protons in the Universe exactly matches the number of electrons. They are such different particles with totally different cross sections. So, first of all, is this true? And, secondly, how could it be that they have been produced in the same amount after the Big-Bang? Define path for packages in the LaTeX file (analog of \input@path or \graphicspath for \usepackage) What do you call someone who acts and thinks it is helpful, even though they do not know the context of what is going on? What is a name for a person who assumes they are doing something helpful, even though they are ignorant to the situation? Someone who reacts without bothering to understand what’s going on, and feels as though they are doing good? Is there such a word?   For instance, someone who pulls another out of the pool, and pats them self on the back for saving them from drowning...without ever asking if the person was drowning or merely swimming. What are these circular splotches on my negatives? How did Princess Leia survive this? In the Last Jedi movie, there is a scene where      her spaceship is taken down, Princess Leia is thrown into outer space, and seen floating there, frozen.    However, she manages to survive this, while any ordinary human being couldn't.   How did she manage this? Is this done by using the Force? chrome disable or change keyboard shortcut ctrl+shift+c developer tools console? How can I disable the Keyboard Shortcut ctrl+shift+c in Google Chrome to bring up the Developer Tools console?  I find myself trying to copy+paste content from the browser and mistakenly typing ctrl+shift+c when I really want to do ctrl+c instead.  How can I disable the current keyboard binding or change ctrl+shift+c to do the same as ctrl+c in Google Chrome? String output: format or concat in C#? Let's say that you want to output or concat strings. Which of the following styles do you prefer?   var p = new { FirstName = "Bill", LastName = "Gates" }; Console.WriteLine("{0} {1}", p.FirstName, p.LastName); Console.WriteLine(p.FirstName + " " + p.LastName);   Do you rather use format or do you simply concat strings? What is your favorite? Is one of these hurting your eyes?  Do you have any rational arguments to use one and not the other?  I'd go for the second one. How to delete an element from an array in C# How to sum 2 vectors in spherical coordinate system Post Problem Analysis - Rod in a cylindrical time varying magnetic field? A metal rod of length $l$ is placed (as shown in figure) in a cylindrical time varying magnetic field. Find the potential difference across it.   My answer:  As electric fields as forming circles around the centre with magnitude $$\frac12r\frac{dB}{dt}$$ whose magnitude is same along any chord at a fix distance from centre: $$\Delta V=E.l=\frac12r\frac32at^{\frac12}.l$$ $$\Delta V=\frac34arlt^{\frac12}$$  My question: Is $\Delta V =V_M-V_N$ or $\Delta V=V_N-V_M$ $\bf OR$ equivalently which side is at high potential?  Possible    $(i)$ As Field lines are circular from $M$ to $N$, $M$ must be high potential. $(ii)$ As this field line apply a force on electrons- in the rod- towards left, then $M$ must have excess $e^-$ and $N$ must have deficiency; so $N$ would be high potential as $M$ is $(+)$ and $N$ is $(-)$. What is the difference between can and could in 'Can/could you please explain this to me?' Can you please explain this to me?          Could you please explain this to me?   I am unable to figure out which to use which situation. I did google, and some posts say they are both the same, even if the second one is more formal. Other posts say could is the past tense of can, but in the above example, I don't think could is used as past tense of can.  What is correct way to use these words?