BroadCom BCM43227 802.11b/g/  ifconfig shows only eth0 and lo. No wlan0 shows.  I need this problem fixed soon, because I need to be able to take this laptop to do my work.  I tried all of the options on this:   I've installed kernel source, and tried reinstalling the b43, but none of it takes effect. I can't be sure, but I've probably tried it with turning my laptop on for wifi. It has a button to turn it on and off, but it should auto enable with "enable networking".  But, I still can't install any drivers, nor can I get access to my WiFi. My laptop is right next to the router by Verizon. It is fast enough and I have accessed wifi through my Windows OS. But I can't get it to work on this OS.  I'm sorry, I'm really confused about everything. I'm also pretty new to Linux.
After installing Ubuntu 12.04 LTS on my HP Folio 13 I cannot get wireless to work. My kernel is 3.8.0-29-generic and my wireless module is a Broadcom BCM4313.  After running rfkill list all:  0: hp-wifi: Wireless LAN Soft blocked: no Hard blocked: no 1: hp-bluetooth: Bluetooth Soft blocked: no Hard blocked: no 2: hci0: Bluetooth Soft blocked: no Hard blocked: no   The wired connection works fine. The driver activation for Broadcom STA wireless driver fails every time. in the log it says  FATAL: Module wl not found. FATAL: Error running install command for wl   After running lspci -nnk | grep -iEA3 "(wireless|network|wlan)":  02:00.0 Network controller [0280]: Broadcom Corporation BCM4313 802.11bgn Wireless Network Adapter [14e4:4727] (rev 01) Subsystem: Hewlett-Packard Company Device [103c:1795] Kernel modules: bcma 03:00.0 Unassigned class [ff00]: Realtek Semiconductor Co., Ltd. RTS5209 PCI Express Card Reader [10ec:5209] (rev 01)   I have also tried this method and it did not work: .
Sorting hashmap based on keys Getting new files to inherit group permissions on Linux I am having a problem with permissions on a Linux server. I am used to BSD. When a directory is owned by a group the user who owns it isn't in such as www-data, files created in it will be owned by that group. This is important because I want files to be readable by the webserver (which I will not run as root) but so a user can still put new files in the directory. I can't put the users in www-data because then they can read every other users websites.   I want the webserver to read all websites, I want users to be able to change their own.  The permissions are set like this on the folders at the moment....  drwxr-x--- 3 john www-data 4096 Feb 17 21:27 john   It is standard behavior on BSD for permissions to work this way. How do I get Linux to do this? Linux kernel update stuck I just installed a new kernel on Ubuntu GNOME 17.04 that came in through the normal updates. However, it is now stuck for a while on the following line:  Setting up linux-headers-4.10.0-20-generic (4.10.0-20.22) ... Examining /etc/kernel/header_postinst.d. run-parts: executing /etc/kernel/header_postinst.d/dkms 4.10.0-20-generic /boot/vmlinuz-4.10.0-20-generic   Something seems to hang the process. Does someone know what could cause this?  EDIT: This is the content of /boot as requested:  abi-4.10.0-19-generic     grub                          System.map-4.10.0-19-generic abi-4.10.0-20-generic     initrd.img-4.10.0-19-generic  System.map-4.10.0-20-generic config-4.10.0-19-generic  memtest86+.bin                vmlinuz-4.10.0-19-generic config-4.10.0-20-generic  memtest86+.elf                vmlinuz-4.10.0-19-generic.efi.signed efi                       memtest86+_multiboot.bin      vmlinuz-4.10.0-20-generic   EDIT 2: Just tried purging the new kernel but got this:  E: dpkg was interrupted, you must manually run 'sudo dpkg --configure -a' to correct the problem.   Using that command returns me to the original problem. I am stuck now :( Automatic text wrapping in ArcMap layout text element? Install MS Truetype Fonts system-wide for all users I would like to install the MS Truetype Fonts that come through the package ttf-mscorefonts-installer, so I did:  sudo apt-get install ttf-mscorefonts-installer   Accepting the license, the process completes without any errors. The fonts end up in     /usr/share/fonts/truetype/msttcorefonts   as expected. Just to be sure, I also did a  sudo fc-cache -f -s -v   which among other things says in its output:     /usr/share/fonts/truetype/msttcorefonts: caching, new cache contents: 60 fonts, 0 dirs   So far, so good (and inline with question ) However, when I then open any font dialog (e.g. in OpenOffice or the font dialog of the terminal) I don't see all of the new fonts. For Arial, the standard form is missing, but bold and italic are there. Times New Roman is missing altogether.  I can use nautilus to browse to the font directory, double click the Arial.ttf file and see the font in all its beauty. I can even click the install button then and the font is copied over to my personal ./fonts directory and from there on visible to my apps. But it is not picked up from the system directory.  How do I get these fonts available system-wide for all users? Removing clock from the lock-screen I'm using Ubuntu 18.04.  I want to remove the digital clock from the lock screen because I just want to see a good wallpaper there, unobstructed.   How do I go about this? How to make a blank page in Google Chrome at start-up? We've never had an explicit policy around downvoting -- users are free to, if they like, cast all their votes as downvotes. Whether this behavior is desirable or not is another matter.   Now, we do discourage downvoting by making downvotes cost -1 rep to the casting voter. But, there's nothing in our policy that says continual downvoting is bad or wrong or inappropriate.  However, my thoughts on this are changing. I no longer think it is community friendly behavior to cast an extreme number of downvotes, and I am considering an explicit policy forbidding it.  Some data points (as of today):  Total SO upvotes cast: 45,555,530  Total downvotes cast: 365,192  users with more than 100 downvotes cast: 596  users with > 100 downvotes and the lowest ratio of upvotes to downvotes:           |           |         | up:down user id | downvotes | upvotes |  ratio --------+-----------+---------+---------  187712 |       201 |      37 |    0.18    2525 |       580 |     149 |    0.25  136829 |       137 |      43 |    0.31   55943 |       438 |     140 |    0.31   19405 |       236 |      94 |    0.39    5640 |      3299 |    1337 |    0.40  180659 |       126 |      66 |    0.52   78613 |       348 |     198 |    0.56   39892 |       181 |     109 |    0.60     432 |       310 |     197 |    0.63  238704 |       198 |     132 |    0.66   12643 |       170 |     116 |    0.68   18256 |       219 |     152 |    0.69  122428 |       167 |     118 |    0.70  118854 |       120 |      86 |    0.71  105662 |       273 |     201 |    0.73  187690 |       135 |     101 |    0.74    1782 |       573 |     430 |    0.75   (this is a complete list, there are no more below this threshold.)  Based on this data I am leaning towards enforcing a "no more downvotes may be cast" if    You have at least (n) votes cast total Your upvote to downvote ratio is lower than ~ 0.5 Prove that matrix can be square of matrix with real entries Prove that matrix   \begin{bmatrix}1&amp;0&amp;0\\0&amp;-1&amp;0\\0&amp;0&amp;-1\end{bmatrix}  can be square of matrix with all real entries.  I have found one such matrix to be   \begin{bmatrix}1&amp;0&amp;0\\0&amp;1&amp;-1\\0&amp;2&amp;-1\end{bmatrix} but is there an elegant way to do it without any trial and error? How to prove by induction that $\frac{a^n+b^n}{2}\geq\left(\frac{a+b}{2}\right)^n$? I'm about to prove that for any $a,b&gt;0$ and $n\in\mathbb{N},$ the inequality: $\frac{a^n+b^n}{2}\geq\left(\frac{a+b}{2}\right)^n$ holds.   By induction I get: $$\left(\frac{a+b}{2}\right)\cdot\frac{a^n+b^n}{2}$$ $$=\frac{1}{2}\cdot\frac{a^{n+1}+b^{n+1}+ab^n+ba^n}{2}$$ $$=\frac{1}{2}\left(\frac{a^{n+1}+b^{n+1}}{2}+\frac{ab^n+ba^n}{2}\right).$$  Now I have to prove that $$\frac{1}{2}\left(\frac{a^{n+1}+b^{n+1}}{2}+\frac{ab^n+ba^n}{2}\right)$$ $$\leq\frac{a^{n+1}+b^{n+1}}{2}$$ $$\Leftrightarrow a^{n+1}+b^{n+1}\geq ab^n +ba^n.$$ But I don't know how to prove that one, is it possible to be proved by induction ? Thank you. "Actually" vs "really" Linearization of PDE: $0$ is an eigenvalue since all translates of travelling waves are also travelling waves I'm trying to configure a ubuntu server network. [Edit] My ifconfig: lo: flags=73&lt;UP,LOOPBACK,RUNNING&gt; mtu 65536 inet 127.0.0.1 netmask 255.0.0.0 inet6 ::1 prefixlen 128 scopeid 0x10&lt;host&gt; loop txqueuelen 1000 (Loopback Local) RX packets 352 bytes 26160 (26.1KB) RX erors 0 dropped 0 overruns 0 frame 0 TX packets 352 bytes 26160 (26.1KB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0  I edited the /etc/network/interfaces file and here is how it is: auto lo auto eth0 iface eth0 inet static address 192.168.15.141 netmask 255.255.255.0 gateway 192.168.15.1  I'm trying to restart the server and I'm using: sudo ifdown --exclude=lo -a &amp;&amp; sudo ifup --exclude=lo -a  This command is an answer from this link:  And I'm getting the following error: Cannot find device &quot;eth0&quot; Failed to bring up eth0.  I'm pretty lay in configuring a server, so I have no idea what's going on. Can someone help me please? How to show that there is an element of order $51$ in the multiplicative group $(Z/103Z)^∗.$  I can't use Cauchy's theorem since $51$ is not prime. PostGIS Geometry Query returns "Error: Operation on mixed SRID geometries" only for certain values ASP.NET Web Site or ASP.NET Web Application? When I start a new ASP.NET project in Visual Studio, I can create an ASP.NET Web Application or I can create an ASP.NET Web Site.  What is the difference between ASP.NET Web Application and ASP.NET Web Site? Why would I choose one over other?  Is the answer different based on which version of Visual Studio I am using? Using Windows 10 in a virtual machine. Can it be done? I am currently running 8.1. I'd like to try out Windows 10 and if I like it upgrade. If not, I'll keep running as I am.   I've never used a virtual machine before: can Window 10 be used from a virtual machine as a "sandbox", and if so how? How do I draw a badge on my Dock icon using Cocoa? G is the product of its Sylow subgroups I want to prove the following:     If every Sylow subgroup of $G$ is a normal subgroup, then $G$ is isomorphic to the product of its Sylow subgroups.   So far, I have gotten to realize that for every prime factor $p_i$ of $|G|$, there is exactly one Sylow subgroup and that these form a partition of $G$. However, I am having trouble finding the isomorphism between $G$ and the product which I will call $G_1 \times \ldots \times G_r$. My idea was just to use the mapping $(g_1, \ldots, g_r) \mapsto g_1\ldots g_r$, which is a bijection, but I don't see whether it is a homomorphism. In general, not all elements of $G_i$ commute with elements of $G_j$, so one cannot simply change the order of the elements in the product. Difference between spin and polarization of a photon I understand how one associates the spin of a quantum particle, e.g. of a photon, with intrinsic angular momentum. And in electromagnetism I have always understood the polarization of an EM wave as the oscillations of the E and M field, not necessarily being  aligned with the direction of propagation of the wave.     Questions:   But when one talks about the polarization of a photon in Quantum Mechanics, how does it really differ from its spin?  Are they somehow related and what's the physical idea behind photon polarization in contrast to photon-spin? Feel free to use mathematical reasonings as well if you see it fit!