Consider the canonical example of a Unix fork bomb:  DANGER: running the following command, might crash your system.  :(){ :|: &amp; };:   I wonder why &amp; (background) is needed in order to use up all of the system's resources - after all the function : is recursive? Also, I have attempted to execute : without &amp;, but in this case Bash doesn't accept the syntax, why?
I get how a normal fork bomb works, but I don't really understand why the &amp; at the end of the common bash fork bomb is required and why these scripts behave differently:  :(){ (:) | (:) }; :   and   :(){ : | :&amp; }; :   The former causes a cpu usage spike before throwing me back to the login screen. The latter instead just causes my system to freeze up, forcing me to hard reboot. Why is that? Both continually create new processes, so why does the system behave differently?   Both of the scripts also behave differently from  :(){ : | : }; :   which doesn't cause any problems at all, even though I would have expected them to be alike. The bash manual page states that the commands in a pipeline are already executed in a subshell, so I'm led to believe that : | : should already suffice. I belive &amp; should just run the pipeline in a new subshell, but why does that change so much?  Edit: Using htop and limiting the amount of processes, I was able to see that the first variant creates an actual tree of processes, the second variant creates all the processes on the same level and the last variant doesn't seem to create any processes at all. This confuses me even more, but maybe it helps somehow?
Height of colorbox So I know I've heard this saying in American English before but I just can't quite find the original.  I have come up with several made up variations like:   I don't send the Navy (or whole army, or a battalion) when all you need is a diplomat. Don't buy the whole cow when all you need is milk.   What's the more commonly heard saying/phrase for this of expression? If $\sum_{n=1}^{\infty} a_n$ is absolutely convergent, then $\sum_{n=1}^{\infty} (a_n)^2$ is convergent I know the definition of Airplane mode is all communications and radio signals are blocked. But is it possible to turn off the "calling/receiving" part of the phone so your phone is not connecting to a cell tower and only allow Wifi? I've looked into a couple of apps in Google Play but they're either not working or out of date with newer versions of Android.   I know there is strong opinions on both sides of the issue but I'm worried about radiation from my phone since i use it a lot in bed and I hold the phone close to my head and face. At night I'm not worried about receiving calls, so I just want to turn off the phone part and  use WiFi. Is there a way? Or am i just crazy and paranoid? Where is "the" used? Is there a rule? Why no definite article in "Shops are open late in summer"? Notice these sentences:   Shops are open late in summer.   Summer is a traditionally viewed as a slow season for games.   At the summer solstice, the days are longest and the nights are shortest.   it's time to start thinking about what 2016's Song of the Summer will be.    In English class, they told us that "the" is used for the things that are known.  One example for this was a phrase like "The man who killed his wife".  So when we are speaking of that man, we know what he did. Somehow we know something more than nothing about him. He's not just every man in the world.     So Now I'm confused about why "the" is not used in the first and second sentences. Can anyone please explain it for me? Why are there two sets of the Ctrl, Alt, and Shift modifier keys when only one of each is necessary? I am trying to add jQuery to my page (it is not being added by default). The file is adding to the page but after drupal.js causing the error:  SCRIPT5009: 'jQuery' is undefined  drupal.js, line 5 character 1    The code that adds drupal.js to the page in common.inc  ... 'misc/drupal.js' =&gt; array(           'data' =&gt; 'misc/drupal.js',           'type' =&gt; 'file',           'scope' =&gt; 'header',           'group' =&gt; JS_LIBRARY,           'every_page' =&gt; TRUE,           'weight' =&gt; -1,           'preprocess' =&gt; TRUE,           'cache' =&gt; TRUE,           'defer' =&gt; FALSE,         ), ...   In my module hook_init I have:    drupal_add_js('misc/jquery.js', array(     'group' =&gt; JS_LIBRARY,     'weight' =&gt; -20,     'cache' =&gt; TRUE,   ));   I would think with a lower weight it would load before drupal.js?  The header of the page contains the following scripts:  &lt;script type="text/javascript" src="http://mysite.com/misc/drupal.js?mqdxrf"&gt;&lt;/script&gt; &lt;script type="text/javascript" src="http://mysite.com/misc/jquery.js?mqdxrf"&gt;&lt;/script&gt; &lt;script type="text/javascript" src="http://mysite.com/misc/jquery.once.js?mqdxrf"&gt;&lt;/script&gt; &lt;script type="text/javascript" src="http://mysite.com/sites/default/files/languages/nl_c9aC92_wtuULa79-hTFcGPM53oqk1yKwciOa_Q3yO28.js?mqdxrf"&gt;&lt;/script&gt; &lt;script type="text/javascript" src="http://mysite.com/sites/all/modules/lang_dropdown/msdropdown/jquery.dd.js?mqdxrf"&gt;&lt;/script&gt; &lt;script type="text/javascript" src="http://mysite.com/sites/all/modules/lang_dropdown/lang_dropdown.js?mqdxrf"&gt;&lt;/script&gt; &lt;script type="text/javascript" src="http://mysite.com/sites/all/modules/devel/devel_krumo_path.js?mqdxrf"&gt;&lt;/script&gt; Eclipse doesn't start on Ubuntu 18.04 I installed eclipse via Ubuntu Software. When I start it, it take some seconds and then comes an error window showing the path of the error.  The following is the .log file:  !SESSION Wed May 02 12:53:28 BRT 2018 ------------------------------------------ !ENTRY org.eclipse.equinox.launcher 4 0 2018-05-02 12:53:28.587 !MESSAGE Exception launching the Eclipse Platform: !STACK java.lang.ClassNotFoundException: org.eclipse.core.runtime.adaptor.EclipseStarter     at java.base/java.net.URLClassLoader.findClass(URLClassLoader.java:466)     at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:566)     at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:499)     at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:626)     at org.eclipse.equinox.launcher.Main.basicRun(Main.java:584)     at org.eclipse.equinox.launcher.Main.run(Main.java:1438)     at org.eclipse.equinox.launcher.Main.main(Main.java:1414)   What is the problem and how can I fix it? Via command line, I have a log file I'd like to keep track of.  What I want is to have, basically, a tail that refreshes when the log is updated making the text scroll upwards as new lines are appended to the log file.  Is there anything out there that does that without having to write some code? Is there a way to make rigid body interact with softbody physics? Problem :   Solve in $\mathbb N$ :   $8n+9\equiv 0\pmod{1163}$  The mathematics give me : $n=435+1163k$ , $k\in\mathbb N$   $1163$ is a prime number   $8n\equiv -9\pmod{1163}$   $8n\equiv 1154\pmod{1163}$   I don't know any ideas to complete my work ?   I have to see your hints Number of homomorphisms from $(\mathbb Q^+ , \,\cdot\,)$ to $(\mathbb Z_n , +)$ How many homomorphism are there from $(\mathbb Q^+ , \,\cdot\,)$ to $(\mathbb Z_n , +)$?   Could anyone give a hint how to proceed? I couldn't even start Using divisibility theorems, prove that if $\gcd(a,b)=1$ and $a|c$ and $b|c$, then $ab|c$.   This is pretty clear by UPF, but I'm having some trouble proving it using divisibility theorems. I was looking at , and if this could be proven, then the solution would follow immediately. iPhoto had it's own trash, and when you've emptied it, files moved to the system trash. I cannot find this in the new Photos app. When I delete files, they don't appear in the system trash. Shouldn't the Terms of Service use Stack Overflow, Inc.? The  still uses the term Stack Exchange, Inc. However, I believe that the name is now Stack Overflow, Inc. , so I believe that should be changed to that. It is weird to have the wrong name in a legal document.   Yes, I actually read the Terms of Service. You should also do that. Salesforce, Oracle and the Seven Dwarfs Over my time as a Salesforce developer, I've written some code which on occasion managed to surface Oracle plsql exceptions and curiously the error text contains the name of one of Disney's .  I've teased out Doc, Grumpy, Happy, Bashful and Sneezy. I'm sure the other two are not far away.   What is the underlying "thing" on the database platform that is named after a Dwarf? Why were these named after Dwarves?      java.sql.SQLException: ORA-30006: resource busy; acquire with WAIT   timeout expiredORA-06512: at "DOC.CAPEX", line 2200ORA-06512: at line   1: SQLException while executing plsql statement: {call   cApex.update_sysmodstamp(?)}([       java.sql.SQLException: ORA-30006: resource busy; acquire with WAIT   timeout expiredORA-06512: at "GRUMPY.CAPEX", line 2563ORA-06512: at   line 1: SQLException while executing plsql statement: {call   cApex.update_sysmodstamp(?)}([       java.sql.SQLException: ORA-30006: resource busy; acquire with WAIT   timeout expiredORA-06512: at "HAPPY.CAPEX", line 2715ORA-06512: at   line 1: SQLException while executing plsql statement: {call   cApex.update_sysmodstamp(?)}([       java.sql.SQLException: ORA-30006: resource busy; acquire with WAIT   timeout expiredORA-06512: at "BASHFUL.CAPEX", line 2715ORA-06512: at   line 1: SQLException while executing plsql statement: {call   cApex.update_sysmodstamp(?)}([       java.sql.SQLException: ORA-30006: resource busy; acquire with WAIT   timeout expiredORA-06512: at "SNEEZY.CAPEX", line 2718ORA-06512: at   line 1: SQLException while executing plsql statement: {call   cApex.invalidate_agc(?,?)}([      Error: ORA-20000: ORA-06512: at "SNEEZY.SIMPORTLOOKUP", line 850   ORA-06512: at "SNEEZY.SIMPORTLOOKUP", line 823 ORA-06512: at line 1 :   SQLException while executing plsql statement: {call   sImportLookup.get_by_ext_id_text(?,?,?,?,?,?,?)}([ What is CUPS server and how to share a printer (Locally or over a network) The title tells you all, except that it's about sharing printers.   How do I connect to a shared printer on the network through CUPS or terminal? How was this answer posted after this question was closed? Finding the expected value of a continuous random variable with a polynomial function. Update finding the integral. An insurance company's monthly claims are modeled by a continuous, positive random variable $X$ whose probability density function is proportional to $(x+1)^{-4}$ where $0 \lt x \lt \infty$   I need help understanding the reasoning behind the answer:  the PDF is given by:  $1 =\int_0^{\infty} \frac{k}{(1+x)^{-4}}$   Here is my first issue in the first step, where does K come from? We are given the pdf to be $\frac{1}{(x+1)^{4}}$ So to me it would stand that the function we are given is the PDF because it says thats the pdf, and we are then to find the expected value from here which would be equivalent to:  $\int_0^{\infty} x(1+x)^{-4}$ by definition of expected value  My guess would be that the words "proportional to" are key as to why we have a K introduced can someone explain this?  I understand everything except when taking the integral because and solving for 1 because I arrive at $\frac{3k}{(1+x)^4}$ rather than $\frac{-1}{3(1+x)^4}$  Taking the integral of $(1+x)^4$:  $u=1+x$ $du=1dx$ and   $\frac{u^{-4+1}}{-4+1} dx$  which gives $\frac{-3k}{(1+x)^3}$  Which gives me $k=\frac{1}{3}$ when solving $1=\frac{-3k}{(1+x)^4} \Big\vert_0^{\infty}$ rather than $k=3$ as the answer which is the correct answer. Can someone please explain this to me? Proving that orthogonal vectors are linearly independent I am trying to prove that $a_1$, $a_2$, $a_3$ are linearly independent.  I am asked to use vector product and prove that if $c_{1}a_{1} + c_{2}a_{2} + c_{3}a_{3} = 0$ then $c_1 = c_2 = c_3 = 0$  I am completely stuck on where to go with this problem. I would think that linearly independent then the null space of the space can only be equal to $0$. Would this prove it?