I am trying  to run any command using sudo, but the cursor just blinks when pressing ENTER, and nothing happens. Then:  sem@sem:~$ sudo apt update --fix-missing sudo: unable to resolve host sem   Any suggestions?  Thanks!
And when I tried the following commands /etc/hostnames and /etc/hosts, it says:  bash: permission denied.
I want to work with unsigned 8-bit variables in C++.  Either unsigned char or uint8_t do the trick as far as the arithmetic is concerned (which is expected, since AFAIK uint8_t is just an alias for unsigned char, or so the debugger presents it.  The problem is that if I print out the variables using ostream in C++ it treats it as char.  If I have:  unsigned char a = 0; unsigned char b = 0xff; cout &lt;&lt; "a is " &lt;&lt; hex &lt;&lt; a &lt;&lt;"; b is " &lt;&lt; hex &lt;&lt; b &lt;&lt; endl;   then the output is:  a is ^@; b is 377   instead of   a is 0; b is ff   I tried using uint8_t, but as I mentioned before, that's typedef'ed to unsigned char, so it does the same.  How can I print my variables correctly?  Edit: I do this in many places throughout my code.  Is there any way I can do this without casting to int each time I want to print? Getting hybrid graphics to work nvidia-prime GT650M Prove that $f'(0)$ exists and $f'(0) = b/(a - 1)$ How can I get a DisplayLink USB monitor work under Ubuntu? I have a DisplayLink-based external USB monitor, which has both power and data over USB, and seems to work perfectly under Windows 7, but only can display a text console under Ubuntu 10.10, and that I can only use when I am actually switched to it. So the only Use I can have so far is to have some text-based monitoring or console that I can watch while working on the graphic display.   I know there are some development done for DisplayLink, but I never could get it to actually run properly.   Yes, I tried the detailed setup described in other , but they did not work, and instead crashed my X that I had to restore.   Merci :-) How can I find the cheapest prepaid SIM card for a given country? Next month I am traveling to country X, where I would need Y minutes of calls, Z text messages and most importantly Q megabytes of data. How can I find the cheapest/most reliable SIM card for my needs? Now that the , I've been seeing tag-only suggested edits from 1500-rep users.  For example, one had the summary of 'burninating [tagThatWasRemoved]'.  It's very tempting to reject these as Too Minor, but I know that these users used to have a Retag privilege (and are obviously trying to participate in a burnination.)  What should we do for tag-only edits from high(er) rep users? How to fix pagination for custom loops? XML DML for 2008 R2..How to modify nested Elements I want to have a  video background that will loop on some frames of my presentation. Can anyone help me to do that? Novel(s) based on humanity fleeing from Earth and regressing to a pre-industrial state on a Colony so as to escape detection Shortly before his death, my father spoke to me about a series of novels that he had just finished reading which had a fascinating concept.  However I soon forgot the title(s) and author and I've been absolutely desperate to find out what they were.  The premise (as I understood) was that humanity had expanded out from the solar system into the local star systems before coming into contact with an incredibly aggressive species which was focused on wiping out the entire species.  Earth and her colonies were lost as remnants of the species fled.  Eventually it was decided by the military leadership to set up a colony in order to rebuild the human race.  However, in order for this colony to escape detection and to keep humanity from going back out into space and thus potentially running into this hostile alien race again, a series of satellites were set up around the planet chosen that would lock onto and destroy any form of technology (and usually the surrounding city) that went beyond pre-industrial standards.    One of the series protagonist is a long living android who possesses the consciousness of a human who was present at the original founding of the colony (and who seems shielded from detection) which observes as civilization is repeatedly regrown and torn down again and who attempts to try and reverse humanities self imposed lot in life.      From what I understood this was a series of novels, but I could be wrong. I've been trying to find this for years on my own with only a rough plot line as a guide and it's gotten me nowhere. How to make a circular array using offset object as center? Editing LaTeX generated PDF Is there an application (in Windows, Unix, or Mac) that allows you to edit the LaTeX generated PDF. I know there is pdfsync, but it only gives you the line, and then you have to search where in the line you want to make the change. This is OK sometimes, for a couple of changes, but when there are lots of changes it becomes really tedious.  I would really like to accelerate this process of correcting mistakes (mostly grammar, missing commas etc.). in my document, without going through all the markup. Multiplication principle and permutation Definition of Multiplication principle in Principles and Techniques in combinatorics by Chuan-Chong, Khee-Meng is given as:      Let $$\prod_{i=1}^rA_i=A_1\times\dots\times A_r=\{(a_1,\dots,a_r) | a_i\in A_i, i=1,\dots,r\}$$ denote the cartesian product of the finite sets $A_1,\dots,A_r.$ Then $$\left\vert \prod_{i=1}^r A_i \right\vert=|A_1|\times\dots\times|A_r|.$$   I want to know how this principle is applies in defining $P_r^n=n(n-1)\cdots2\cdot1$, ie, what are sets $A_1,\dots,A_r$ here? Who in the DC Universe can stop Superman if he has a breakdown? Is there anything or anyone in the DC universe that can defeat Superman just in case he goes berserk on everybody?  Maybe Batman stores kryptonite in his Cave or something. I don't know if Batman actually has kyptonite, the example was just a theoretical example.  Who can stop Superman if needed, and how? How to use AT commands in Android by 'root' the phone We have various Android devices from Spike, Samsung, Micromax, etc. How can we issue AT commands from Android to the modem? We searched in Google Play but did not find any app related to this.   suggests:     [F]irst you have to root the phone...`    How can we do this? When looking for the path to an executable or checking what would happen if you enter a command name in a Unix shell, there's a plethora of different utilities (which, type, command, whence, where, whereis, whatis, hash, etc).  We often hear that which should be avoided. Why? What should we use instead? Is it: My apples and orange are/is wrong? Simple question:     My apples and orange are wrong   or     My apples and orange is wrong   I am not a native English speaker, and I am having some trouble choosing between plural are or singular is for that kind of example. Vim: How do I search for a word which is not followed by another word? The following could have shown up as an exercise in a basic Abstract Algebra text, and if anyone can give me a reference, I will be most grateful.  Consider a set $X$ with an associative law of composition, not known to have an identity or inverses. Suppose that for every $g\in X$, there is a unique $x\in X$ with $gxg=g$. Show that $X$ is a group.  Note that I’m not asking for a proof (though a really short one would please me!), just some place where this has been published. I'm trying to install wifi drivers for a particular mini wifi card i bought. The output of lsusb is:  0bda:f179 Realtek Semiconductor Corp   I've searched everywhere for drivers, but could not find anything. Any help?  Thanks