I cannot install any packages
How do I install the ubuntu-restricted-extras package?
Is there a modal command for MakeLowercase? Analog to  question I've been wondering WHAT is to \lowercase as \bfseries is to \textbf? (... and for uppercase, or \MakeLowercase and MakeUppercase, etc., which also seem to be text-block commands as explained .)  Is there a "switch"/"declaration"/"modal command" (what is the correct term here?, is there a difference between them?) that would allow one to turn something into lowercase/uppercase in the same way that one would use \scshape for example, i.e., not as text-block command with the curly braces?  Or how to create such a command?  I couldn't find any clue on the forum. Grub not showing on startup for Windows 8.1 Ubuntu 13.10 Dual boot Argument list too long for ls I get the following error when trying to ls *.txt | wc -l a directory that contains many files:  -bash: /bin/ls: Argument list too long   Does the threshold of this "Argument list" dependent on distro or computer's spec?  Usually, I'd pipe the result of such big result to some other commands (wc -l for example), so I'm not concerned with limits of the terminal. Weather Resistant Outlets vs Weather Proof Box Do I need to activate the firewall? I only use Ubuntu for a home desktop use? I am a novice at Ubuntu (12.04).  I have it on my netbook which I use mainly for surfing the net, learning python and remote desktop into my work computer.    Do I need to enable a Firewall type software?  If so, what would you suggest, and what are sensible default suggestions? I am looking for a driver for the TP-Link AC600 Archer T2U Nano, on Kubuntu 18.04 (kernel version 4.15.0-51-generic).   I already tried different drivers, none of them worked. Why should two sub-atomic (or elementary particle) - say electrons need to have identical static properties - identical mass, identical charge? Why can't they differ between each other by a very slight degree? Is there a theory which proves that?  Imagine an alien of size of order of Milky-way galaxy examining our solar system with a probe of size of 10's of solar system dimension and concludes that all planets are identical. Some people love creating or fostering the creation of events that are noisy, chaotic and fun, such as parties, arguments, reunions, etc. Sometimes there's a negative connotation to this (like in provoking an argument), but sometimes there is not (like in organising a big, noisy party).  The word I'm looking for would be the English equivalent to the Spanish armadanzas, just in case this is helpful.  Any ideas? I have asked this question before ( and  )  My problem is that my Self Encrypted Disk (SED) have to NOT spin down even on suspend!  I have tried , but it did not work and the disk spin downs anyway !  The problem is that if the disk spins down, because it is on suspend, it does not show the "de encryption" prompt, and boots back up on RAM, but crashed due to IO error on the disk! (that's what the disk is suposed to do !)  Anyone on how to NOT (as in NEVER) spin down a HDD ? (yes this goes against all logic but this particular case)   Thanks a lot !  Would that be useful ?   sudo hdparm -I /dev/sda [sudo] password for xqua:   /dev/sda:  ATA device, with non-removable media     Model Number:       ST500LT015-9WU142                            Serial Number:      W0VBZQQ7     Firmware Revision:  0001SDM7     Transport:          Serial, ATA8-AST, SATA 1.0a, SATA II Extensions, SATA Rev 2.5, SATA Rev 2.6 Standards:     Used: unknown (minor revision code 0x0029)      Supported: 8 7 6 5      Likely used: 8 Configuration:     Logical     max current     cylinders   16383   16383     heads       16  16     sectors/track   63  63     --     CHS current addressable sectors:   16514064     LBA    user addressable sectors:  268435455     LBA48  user addressable sectors:  976773168     Logical  Sector size:                   512 bytes     Physical Sector size:                  4096 bytes     Logical Sector-0 offset:                  0 bytes     device size with M = 1024*1024:      476940 MBytes     device size with M = 1000*1000:      500107 MBytes (500 GB)     cache/buffer size  = 16384 KBytes     Form Factor: 2.5 inch     Nominal Media Rotation Rate: 5400 Capabilities:     LBA, IORDY(can be disabled)     Queue depth: 32     Standby timer values: spec'd by Standard, no device specific minimum     R/W multiple sector transfer: Max = 1   Current = 1     Advanced power management level: 254     Recommended acoustic management value: 208, current value: 0     DMA: mdma0 mdma1 mdma2 udma0 udma1 udma2 udma3 udma4 udma5 *udma6           Cycle time: min=120ns recommended=120ns     PIO: pio0 pio1 pio2 pio3 pio4           Cycle time: no flow control=120ns  IORDY flow control=120ns Commands/features:     Enabled Supported:        *    SMART feature set        *    Power Management feature set        *    Write cache        *    Look-ahead        *    Host Protected Area feature set        *    WRITE_BUFFER command        *    READ_BUFFER command        *    NOP cmd        *    DOWNLOAD_MICROCODE        *    Advanced Power Management feature set             Power-Up In Standby feature set        *    SET_FEATURES required to spinup after power up             SET_MAX security extension        *    48-bit Address feature set        *    Device Configuration Overlay feature set        *    Mandatory FLUSH_CACHE        *    FLUSH_CACHE_EXT        *    SMART error logging        *    SMART self-test        *    General Purpose Logging feature set        *    WRITE_{DMA|MULTIPLE}_FUA_EXT        *    64-bit World wide name        *    IDLE_IMMEDIATE with UNLOAD        *    Write-Read-Verify feature set        *    WRITE_UNCORRECTABLE_EXT command        *    {READ,WRITE}_DMA_EXT_GPL commands        *    Segmented DOWNLOAD_MICROCODE        *    Gen1 signaling speed (1.5Gb/s)        *    Gen2 signaling speed (3.0Gb/s)        *    Native Command Queueing (NCQ)        *    Host-initiated interface power management        *    Phy event counters        *    Idle-Unload when NCQ is active             Device-initiated interface power management        *    Software settings preservation        *    SMART Command Transport (SCT) feature set        *    SCT Write Same (AC2)        *    SCT Features Control (AC4)        *    SCT Data Tables (AC5)             unknown 206[12] (vendor specific)        *    reserved 69[4]        *    reserved 69[7] Logical Unit WWN Device Identifier: 5000c5006a036439     NAA     : 5     IEEE OUI    : 000c50     Unique ID   : 06a036439 Checksum: correct Delete all files except specified files/folders using command line? I have a folder containing a lot of folders and different files with the following structures :  NASA │ ├── a │   ├── doc1 │   ├── doc2 │   ├── doc3 │   ├── folder1 │   └── folder2 │ ├── b │   ├── doc1 │   ├── doc2 │   ├── doc3 │   ├── folder1 │   └── folder2 │ ├── c │   ├── doc1 │   ├── doc2 │   ├── doc3 │   ├── folder1 │   └── folder2 │ ├─ x ├─ y └─ z          I want to delete the content of the folder (NASA/) except specified folders and files.   For example I want to keep a folder, b folder and x file.     I tried   :   rm !(a/) -r NASA/   And (as explained in the answer ):  find NASA/ -type f ! -iname "x" -delete   But this is not very straight forward and I have to use a bash script.    Am I missing a more easy way ? How can I do this in a single command? Powering NiChrome wire from battery I'm looking to power nichrome wire from battery. The problem I ran into is that desired length/width of the wire has very small resistance ~ 8 Ohm.  Several kinds of batteries I've tested have internal resistance much higher then that, which leads to wire staying cold and battery getting hot.  Is there any way to increase current drawn from the battery? Some kind of amplifier maybe?  Edit:    1.2V(rechargable) and 1.5V one, while not getting hot itself did not provide enough power to heat the wire. 3V did not provide enough power, even stacking 3 of them in series, only provided about 1V of voltage on the wire, and not enough amperage to heat the wire. 9V battery did provide enough amperage to heat the wire, but at the same time got very hot very quickly itself.   PS. I was wondering if  might work for this purpose? How to add home directory path to be discovered by Unix which command? CSS Display an Image Resized and Cropped I want to show an image from an URL with a certain width and height even if it has a different size ratio.  So I want to resize (maintaining the ratio) and then cut the image to the size I want.  I can resize with html img property and I can cut with background-image.  How can I do both?  Example:  This image:     Has the size 800x600 pixels and I want to show like an image of 200x100 pixels   With img I can resize the image 200x150px:  &lt;img      style="width: 200px; height: 150px;"      src="http://i.stack.imgur.com/wPh0S.jpg"&gt;    That gives me this:    &lt;img style="width: 200px; height: 150px;" src="https://i.stack.imgur.com/wPh0S.jpg"&gt;       And with background-image I can cut the image 200x100 pixels.  &lt;div      style="background-image:            url('https://i.stack.imgur.com/wPh0S.jpg');      width:200px;      height:100px;      background-position:center;"&gt;&amp;nbsp;&lt;/div&gt;    Gives me:        &lt;div style="background-image:url('https://i.stack.imgur.com/wPh0S.jpg'); width:200px; height:100px; background-position:center;"&gt;&amp;nbsp;&lt;/div&gt;      How can I do both?  Resize the image and then cut it the size I want? 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. What are the differences between a multidimensional array and an array of arrays in C#? I recently upgraded to Snow Leopard, from Leopard and I was using an awesome app called  that let you remap your keys, set scripts/macros and even had repeat functionality.   However, this app doesn't seem to be in active development anymore, and 10.6 broke the ability to bind certain modifier keys (Shift) with other keys.   I totally miss things like Shift+Insert for paste (Linux/Windows), setting Ctrl+Shift+Esc for Activity Monitor, and Ctrl+Alt+Del for the login window.   So, how can I achieve this instead? Prove that $\lim_{N\rightarrow\infty}(1/N)\sum_{n=1}^N f(nx)=\int_{0}^1f(t)dt$ Suppose $f$ is continuous and periodic on the reals with period 1. Prove that if $x\in[0,1]$ is an irrational number, then  $$\lim_{N\rightarrow\infty}\frac{1}{N}\sum_{n=1}^N f(nx)=\int_{0}^1f(t)dt$$   Suggestion: First consider $f(t) = e^{2\pi(ikt)}$ where k is an integer.   I can see that this is a limit of a weighted average, but the suggestion throws me off. I've seen the suggestion in fourier transforms but it's not clicking at the moment. Any help would be welcome. I'm trying to to execute a script, which uses the command rename.   When I execute it, I get a message rename: command not found. Any ideas?   if [[ -z '$3' ]]; then     shopt -s dotglob     rename "$EXPRESSION" ./* else     rename "$EXPRESSION" "$3" fi In JavaScript, the "this" operator can refer to different things under different scenarios.   Typically in a method within a JavaScript "object", it refers to the current object.  But when used as a callback, it becomes a reference to the calling object.  I have found that this causes problems in code, because if you use a method within a JavaScript "object" as a callback function you can't tell whether "this" refers to the current "object" or whether "this" refers to the calling object.  Can someone clarify usage and best practices regarding how to get around this problem?     function TestObject() {             TestObject.prototype.firstMethod = function(){                       this.callback();                       YAHOO.util.Connect.asyncRequest(method, uri, callBack);              }              TestObject.prototype.callBack = function(o){               // do something with "this"               //when method is called directly, "this" resolves to the current object               //when invoked by the asyncRequest callback, "this" is not the current object               //what design patterns can make this consistent?               this.secondMethod();             }             TestObject.prototype.secondMethod = function() {              alert('test');             }         } I recently read this , which stated:     For scientists trying to design a compound that will attach itself to,   and modify, a target disease pathway, the critical first step is to   determine the electronic structure of the molecule. But modeling the   structure of a molecule of an everyday drug such as penicillin, which   has 41 atoms at ground state, requires a classical computer with some   $10^{86}$ bits—more transistors than there are atoms in the observable   universe. Such a machine is a physical impossibility. But for quantum   computers, this type of simulation is well within the realm of   possibility, requiring a processor with 286 quantum bits, or qubits.   Along with this resource estimate for penicillin, I've also seen  of the number of qubits required to model the ground state of caffeine (160 qubits). Given that the above report offers no reference(s) (probably in the name of business intelligence) and much Internet searching and looking into the quantum chemistry literature has come up short, my question is: Where are these resource estimates coming from – is there a journal article that published these numbers? I would really like to identify the methodology and assumptions used in making these estimates.