I want to list all packages that are not automatically installed as dependencies.    E.g. I've installed build-essential, whose dependencies include gcc.  I want to output a list that contains build-essential, but not gcc.
I'd like to get a list of packages installed manually by apt or aptitude and be able to find out whether a foobar package was installed manually or automatically. Is there any neat way of doing that from the command line?
The simplistic undergrad explanation aside, I've never really understood what energy really is. I've been told that it's something when converted from one kind of something to another kind, or does some "work", as defined by us, but what is that something?  Moreover, if the total amount of energy in the universe is finite and we cannot create energy. Then, where did it come from? I've learned from thermodynamics where it goes, but where does it come from?  I know this sounds like something trivially simple, but there is so much going on in the physical universe and I just can't grasp what it is. Maybe it is because I lack the mathematical understanding that I can't grasp the subtle things the universe is doing. Still, I want to understand what it is doing.  How do I get to the point of understanding what it's doing?  (Note: What prompted me to ask this was . I'm afraid that it just puzzled me further and I sat there staring at the screen for a good 10 minutes.) By integration by parts and the substitution $x = \sin t$ we can easily calculate the integral $\int_{0}^{1} \ln (x+ \sqrt{1-x^2})dx$ which equals to $\sqrt{2} \ln (\sqrt{2} +1) -1.$ I’ve tried to use the same substitution $x = \sin t$ to calculate the integral $ \int_{0}^{1} \frac {\ln (x+ \sqrt{1-x^2})}{x}dx,$ which becomes $$ \int_{0}^{\frac {\pi}{2}} \frac {\ln \sin (t+ \frac {\pi}{4})}{\sin t}dt$$ It seems difficult to solve the particular integral. Any help? I have a little problem with the placement of my picture. I want to insert it at the end of the introduction chapter but its place is not where I want.   I think the problem become from the:  \begin{figure} ... \end{figure}   Because when I insert the picture without using \begin{figure}... the picture is at the end of the chapter as I want.   Look the picture below. Detecting and acting on keyboard direction keys in Java Show Previous/Next Posts navigation only inside the same category Is it possible to force previous/next navigation to browse through the posts (back and forth) that are only inside the same category (and to exclude other categories)? Let $f$ and $g$ be entire functions and $g(z)\neq 0$ for all $z\in \mathbb{C}$. If $|f(z)|\le |g(z)|$, can we say $f$ is constant?  Liouville theorem says that an entire bounded function is constant, but g is not given bounded here. So I think it should be false. What else can we say about $f$? Where are all islands and discoverable locations? After taking off in Simpleplanes and flying around over the ocean for a while, I've found a lots of tiny islands all over the place, and a few really big ones that unlock new spawn locations once found.  Large islands appear to also have many discoverable 'locations' around them as well, like airports, carriers, or landmarks.  These locations automatically become available as start points once discovered.  Where can I find all of these major islands, and once there, where should I look to unlock all of the locations? Is there any analytics information that moderators can access for individual questions? My webcam just came on "out of the blue" Verbless sentence I thought I heard my teacher said: 'Don't construct a sentence without a verb.'  Is there such rule in english grammar?     She looks like 70 years old. Perhaps older.   How about the question above? Is it correct? Is there any book that can be used references for wide range of topics in grammar(including syntax, morphology et cetera)? I have finished oxford grammar in use recently and think it wasn't enough for me. Prove that $n! + k$ is a composite number XSL That Returns the XML unchanged I've connected a USB to Serial bridge dongle, and running dmesg | grep tty outputted the following:  [    0.000000] console [tty0] enabled [603199.380677] usb 2-2: cp210x converter now attached to ttyUSB0   So now I'm trying to write to it as per  by running the following:  cat hello.txt &gt; /dev/ttyUSB0   and   sudo cat hello.txt &gt; /dev/ttyUSB0   But both result in the following error:  bash: /dev/ttyUSB0: Permission denied   What am I doing wrong?  Thanks Any idea why the piece of code below does not add the script element to the DOM?  var code = "&lt;script&gt;&lt;/script&gt;"; $("#someElement").append(code); What does the AE/AF lock button do that half-pressing the shutter doesn't? The Sony A6000 has an AEL button, while Nikon SLRs have an AE/AF lock button. What do these do that half-pressing the shutter to lock focus and exposure, and then recomposing, doesn't? I'm used to the latter method, and never used a camera that has a dedicated button.  I read that you have to keep both the AE/AF lock button pressed and the shutter half-pressed while recomposing. Isn't this harder than just keeping the shutter button half-pressed?  I'm aware that you can customize the AE/AF lock button to lock only focus, or only exposure, or both. This leads to two follow-up questions:   Can't you customize the half-press shutter to lock only AE or only AF? If you don't care about this level of customization, does the AE / AF lock button do anything that half-pressing the shutter doesn't? How to restore a system after accidentally removing all kernels? I was trying to delete old kernels, but I must have deleted all of the kernels on my Ubuntu 11.04 laptop. Is there any way to fix this via USB boot or mounting hard drive on another system? I need a command that will wait for a process to start accepting requests on a specific port.    Is there something in linux that does that?  while (checkAlive -host localhost -port 13000 == false)   do some waiting  ... What does size of a directory mean in output of 'ls -l' command? What does size of a directory mean in output of ls -l command? What information does the trace of a matrix give? Why is my Wi-Fi process using 3GB of memory?