Booting Gparted with GRUB
How to change boot priority?
Why doesn't Steam start? When I try to start Steam nothing happens. Reinstall doesn't help.  $ steam Running Steam on ubuntu 13.04 64-bit STEAM_RUNTIME is enabled automatically Installing breakpad exception handler for appid(steam)/version(1378500910_client) Installing breakpad exception handler for appid(steam)/version(1378500910_client) Installing breakpad exception handler for appid(steam)/version(1378500910_client) unlinked 0 orphaned pipes removing stale semaphore last operated on by process 7278 with name 0eBlobRegistryMutex_DC7EBB4AEA41D3C6C74E5EFFD6757CEC removing stale semaphore last operated on by process 7278 with name 0eBlobRegistrySignal_DC7EBB4AEA41D3C6C74E5EFFD6757CEC removing stale semaphore last operated on by process 7278 with name 0emSteamEngineInstance removing stale semaphore last operated on by process 7278 with name 0eSteamEngineLock Gtk-Message: Failed to load module "overlay-scrollbar" Installing breakpad exception handler for appid(steam)/version(1378500910_client) [0913/182910:WARNING:proxy_service.cc(958)] PAC support disabled because there is no system implementation   How to fix it? Select current element in jQuery How to completely remove desktop? I wanted to switch to Xfce (I had KDE and GNOME installed), and I did this :    sudo apt-get install xubuntu-desktop sudo apt-get remove kubuntu-desktop sudo apt-get remove ubuntu-desktop sudo apt-get autoremove   but to my surprise, I could still pick gnome, kde plasma, etc during the log in.  So, how do I completely remove KDE and GNOME desktops? What the matter is vs. what is the matter used in the affirmative I want to know what the matter is with her.  I want to know what's the matter with her. I want to know what's her problem.   Is "I want to know what's the matter with her" and 'what's the matter'  incorrect as Cambridge dictionary suggests (). In their explanation it is suggested that the word 'matter' be replaced with 'problem' as is written in the 3rd example.    Thanks for whatever help you can provide on this.  I've read Rathony's link and agree that his link answered the question about inversion. Now my question is specifically about the correctness of using this wording and if it is correct is there a rule in its usage. Example where $f\circ g$ is bijective, but neither $f$ nor $g$ is bijective Can anyone come up with an explicit example of two functions $f$ and $g$ such that: $f\circ g$ is bijective, but neither $f$ nor $g$ is bijective?  I tried the following: $$f:\mathbb{R}\rightarrow \mathbb{R^{+}} $$ $$f(x)=x^{2}$$  and  $$g:\mathbb{R^{+}}\rightarrow \mathbb{R}$$ $$g(x)=\sqrt{x}$$  $f$ is not injective, and $g$ is not surjective, but $f\circ g$ is bijective  Any other examples? 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. I have just upgraded my system but it boots to Low Graphics mode by default. I have seen questions on how to solve this problem and they all suggest to run a couple of commands from a command-line interface.  But there isn't any command-line console by default in Low Graphics mode and hence, I cannot run those commands. And, the answers I saw to solve the problem doesn't explain this situation either.  How to switch to a command-line console in order to run the commands in Low Graphics mode? I have a dual boot of Windows 10 and Ubuntu 16.04. Recently I upgraded it to 18.04. As soon as I did it, it started showing DISK IS LIKELY TO FAIL SOON (37° C / 99° F).    I checked the status of my disk via Windows and it shows it’s perfectly healthy. I assumed the error occurred because my partition size of Ubuntu was 64GB (which I now increased to 86GB). Please help me out with this.    Edit: The results of smartctl - attributes Error with square bracket in table \begin{table}[ht] \makebox[\textwidth][c]{     \begin{tabular}{ccccc}         \hline         \hline         [] &amp; [] &amp; [] &amp; [] &amp; []\\         [] &amp; [] &amp; [] &amp; [] &amp; []\\         \hline         \hline     \end{tabular} } \caption{test} \end{table}   I cannot run the above code, latex returned an error about missing number, but I can't see anything I am missing.  And the weirdest thing is that  \begin{table}[ht] \makebox[\textwidth][c]{     \begin{tabular}{ccccc}         \hline         \hline         [] &amp; [] &amp; [] &amp; [] &amp; []\\         \hline         \hline     \end{tabular} } \caption{test} \end{table}   This code works.  Anyone have any idea? What is the difference between "gerund" and "infinitive"? What is the difference between "gerund" and "infinitive"? I do not understand the differences.Can you explain them? (Note that I have used bold text frequently simply to highlight the key points of my question for those who do not have the time to read through it thoroughly (it is not very long, however); I hope this is not considered offensive.)  There are many textbooks on multivariable calculus. However, some textbooks on multivariable calculus do not focus very much on the theoretical foundations of the subject. For example, a textbook might state a result along the lines of "the order of partial differentiation is immaterial" without proof and ask the student to use this rule to solve problems. Similarly, theorems such as those due to Green and Stokes are often not proved in their full generality.   Therefore, I ask the following question:      What are some good theoretical   multivariable calculus textbooks?   Since "theoretical" is somewhat ambiguous, let me state the following criteria which I would like a "theoretical" textbook on multivariable calculus to satisfy:   The textbook should be rigorous and it should not state a theorem without proof if the theorem is proved in at least one other multivariable calculus textbook. (Of course, the textbook may omit certain theorems; however, this criterion at least ensures that major theorems in multivariable calculus are not stated without proof and used purely for the sake of computations. Also, this criterion permits the textbook to state an interesting theorem if it is beyond the scope of all multivariable calculus textbooks.) The textbook should be primarily based on developing the theoretical foundations of multivariable calculus; therefore, applications such as learning how to compute the partial derivative of a function, learning how to solve extremum problems, learning how to compute etc. should be kept to a minimum. In particular, the textbook can assume that the reader has already seen at least an informal treatment of the subject where these aspects are emphasized. The textbook should have a rigorous treatment of differentiability in $n$-dimensional Euclidean space (e.g., the inverse and implicit function theorems should be proven), Riemann integration in $n$-space, and differential forms (e.g., Stokes theorem should be proven). It would also be a bonus if the book treated the general concept of a manifold. Textbooks with minimal prerequisites are preferred; however, please feel free to suggest books meeting the above criteria even if the prerequisites are quite demanding. Finally, it would also be preferable, but not essential, for the book to only treat multivariable calculus.   Examples of books meeting the above criteria: "Analysis on Manifolds" by James Munkres, "Principles of Mathematical Analysis" by Walter Rudin, and "Calculus on Manifolds" by Michael Spivak.   Although I have studied theoretical multivariable calculus already (four years ago), I could never find "the perfect book" (relative to myself, of course). Every book has its virtues; Rudin for its elegance, Munkres for its beautiful exposition, and Spivak for its "quick and dirty" approach. I am hoping that someone will be able to suggest a book that (relative to myself) is "perfect". Also, this question can be useful to other students who have not yet studied the subject and wish to learn it.   Thank you very much for all answers! Please do feel free to suggest as many books as you can think of so we can form a big list. Also, please try to explain why a particular book is good or at least why you think it is good. I suppose it is fine to suggest a book that is already suggested provided you have a different view as to why the book is good. I have what is probably a simple question, but it is baffling me right now, so I am hoping you can help me out.  I have a least squares regression model, with one independent variable and one dependent variable. The relationship is not significant. Now I add a second independent variable. Now the relationship between the first independent variable and the dependent variable becomes significant.  How does this work? This is probably demonstrating some issue with my understanding, but to me, but I do not see how adding this second independent variable can make the first significant. If we have a point charge and outside of it we have a non-conducting Gaussian sphere, then Gauss's law says that the net flux should be zero. I agree that the total field lines coming in are equal to the number of field lines coming out, but isn't it true that the magnitude of the electric field at those segments of the sphere where the field is coming in is greater than those where it is coming out? So when we integrate, wouldn't these areas, having a greater electric field, contribute more to the net flux? I don't see why they would cancel each other out. ext4 partition size / free space discrepancies While creating a 250GiB backup partition for my data, I have noticed lots of discrepancies between reported partition size and free space in Nautilus, gParted, df, tune2fs, etc.  At first I thought it was a GiB / GB confusion. It was not.  Then I thought it could be ext4's reserved blocks. It was not.  Im completely puzzled. Here are some images. Here are the steps:   First, NTFS. 524288000 sectors x 512 bytes/sector = 268435456000 bytes = 268.4 GB = 250 GiB.      Nautilus say "Total Capacity: 250.0 GB" (even though its actually GiB, not GB). Apart from that minor mislabeling, so far, so good   Now, same partition, formated as ext4 with gparted:     First, Last and Total sectors are the same. It IS the same 250GiB partition. Used size is 4.11GiB (reserved blocks maybe?)    Nope. Looks like reserved blocks are 12.7 GiB (~5%. ouch!). But... why Total Capacity is now only 246.1 GiB ???. That difference (sort of) matches the 4.11 GiB reported by gparted. But... if its not from reserved blocks, what is it? And why gparted didnt report that 12.7GiB of used space?  $ df -h /dev/sda5 Filesystem            Size  Used Avail Use% Mounted on /dev/sda5             247G  188M  234G   1% /media/BACKUP   df matches Nautilus in reported free space. But.. only 188M used? Shouldnt it be ~12GB? And total capacity is still wrong. So i ran tune2fs to find some clues. (irrelevant output is ommited)  $ sudo tune2fs -l /dev/sda5 tune2fs 1.41.12 (17-May-2010) Filesystem volume name:   BACKUP Filesystem UUID:          613d592e-47f5-4206-96a7-210090d340ef Filesystem features:      has_journal ext_attr resize_inode dir_index filetype extent flex_bg sparse_super large_file huge_file uninit_bg dir_nlink extra_isize Filesystem flags:         signed_directory_hash  Filesystem state:         clean Filesystem OS type:       Linux Block count:              65536000 Reserved block count:     3276800 Free blocks:              64459851 First block:              0 Block size:               4096   65536000 total blocks * 4096 bytes/block = 268435456000 bytes = 268.4 GB = 250 GiB. It matches gparted.  3276800 reserved blocks = 13421772800 bytes = 13.4 GB = 12.5 GiB. It (again, sort of) matches Nautilus.  64459851 free blocks = 264027549696 bytes = 264.0 GB = 245.9 GiB. Why? Shouldnt it be either 250-12.5 = 237.5 (or 250-(12.5+4.11)=~233) ?  Removing reserved blocks:  $ sudo tune2fs -m 0 /dev/sda5 tune2fs 1.41.12 (17-May-2010) Setting reserved blocks percentage to 0% (0 blocks)  $ sudo tune2fs -l /dev/sda5 tune2fs 1.41.12 (17-May-2010) Filesystem volume name:   BACKUP Filesystem UUID:          613d592e-47f5-4206-96a7-210090d340ef Filesystem features:      has_journal ext_attr resize_inode dir_index filetype extent flex_bg sparse_super large_file huge_file uninit_bg dir_nlink extra_isize Filesystem flags:         signed_directory_hash  Filesystem state:         clean Filesystem OS type:       Linux Block count:              65536000 Reserved block count:     0 Free blocks:              64459851 Block size:               4096   As expected, same block count, 0 reserved blocks, but... same free blocks? Didnt I just freed 12.5 GiB ?  $ df -h /dev/sda5 Filesystem            Size  Used Avail Use% Mounted on /dev/sda5             247G  188M  246G   1% /media/BACKUP     Looks like I did. Avaliable space went up from 233 to 245.9 GiB. gparted didnt care at all, showing exactly same info! (useless to post an identical screenshot)  What a huge mess!  I tried to document it as best as I could... So, please can someone give me any clue on what's going on here?   What are those misterious 4.11 GiB missing from NTFS -> ext4 formatting? Why there are so many discrepancies between gparted, Nautilus, tune2fs, df? What is wrong with my math? (questions in bold scattered this post)   Any help is appreciated. While I can not figure what is going on, I am serilously considering giving up on ext4 in favor of NTFS for everything but my / partition.  Thanks! Does GCM (or GHASH) only provide 64-bit security against forgeries? In a  a doubt was voiced about my answer, which claims GCM to requires $2^{128}$ for a successful forgery. The doubt was that the square root needs to be taken meaning the security would be $2^{64}$.  So of course I immediately checked the relevant security theorem ():  $$\mathbf{Adv}^{\text{auth}}_{\operatorname{GCM}[\operatorname{Perm}(n),\tau]}(\mathcal A)\leq \frac{0.5(\sigma+q+q'+1)^2}{2^n}+\frac{q'(\ell_A+1)}{2^\tau}$$  with $\sigma$ being the total plaintext size in blocks, $q$ being the total number of encryption queries, $q'$ being the total number of decryption queries, $n$ being the size in bits of the underlying permutation, $\ell_A$ being maximum authenticated input length in blocks and $\tau$ being the tag size in bits.  Now clearly from this we can see that performing $2^{n/2}=2^{64}$ queries yields a strong enough advantage for a break.  Now my question is: When talking about "n-bits of security" or "needs $2^n$ operations to break", do we usually talk about "online" security, ie queries to an oracle can be done and cost $1$ or "offline" security where no oracles are available or do we need to make this decision depending on the situation?  TL;DR: Does GCM offer 64 or 128 bit security? How to scale a tikzpicture to \textwidth As the output of df -h shows here, something is eating up 5GB of free space. So, it's not available to use.   I'm also noticing sometimes that the hard disk gets filled up to 100% sometimes. So, I had to restart the machine or delete some unncessary files. Only noticed these in /home partition. Don't know whether these two are related, but appreciate if anyone can put some insight into this.  $ df -h Filesystem            Size  Used Avail Use% Mounted on /dev/sda8             100G   92G  2.7G  98% /home I can prove the converse of it, but I cannot do this one. Here is the problem:     Prove that the implicit function theorem implies the inverse function theorem. Can't change mouse influence in proportional editing mode I press O and I see it change to Proportional Editing mode, but when I press G and mouse wheel down/up, or arrow keys down/up, it doesn't change the influence area.    And I am, I press G and then I tried to scroll to change influence, but it's not working.    Done this aswell and it's not working There are many different kind of options that you can do  in order to start using LaTeX on Ubuntu. I would prefer doing that through Eclipse, but if there is a better way of doing it, feel free to write your opinion on why using this instead of something else.