When I run a command which doesn't exist: [root@centos2 ~]# abc bash: abc: command not found... ^C [root@centos2 ~]#  Bash doens't exit (I waited for at least 30 seconds) immediately. I have to sent Crtl + c to exit. It is normal when I run other commands: [root@centos2 ~]# echo 'a' a [root@centos2 ~]#  I'm running on CentOS 8: [root@centos2 ~]# cat /proc/version Linux version 4.18.0-193.6.3.el8_2.x86_64 (mockbuild@kbuilder.bsys.centos.org) (gcc version 8.3.1 20191121 (Red Hat 8.3.1-5) (GCC)) #1 SMP Wed Jun 10 11:09:32 UTC 2020 [root@centos2 ~]# cat /etc/centos-release CentOS Linux release 8.2.2004 (Core)
Often when I mistype a command such as ls (e.g. I hit ENTER before I type 's') there is a long (~2s) delay after the terminal displays:  bash: l: command not found...   I can understand the reasons for a similar delay after an incorrect password is entered, per . But why delay after an unrecognized command? Does FAIL_DELAY in /etc/login.defs affect this also?
The -k option (or --convert-link) will convert links in your web pages to relative after the download finishes, such as the man page says:     After the download is complete,   convert the links in the document to   make them suitable for local viewing.   This affects not only the visible   hyperlinks, but any part of the   document that links to external   content, such as embedded images,   links to style sheets, hyperlinks to   non-HTML content, etc.   So, if I didn't specify -k, can I run wget again after the download and fix that, and if so, what would be the proper command? My guess is wget -c [previous options used] [url] and run it in the same working directory as the file were downloaded to. Is there an alternative to string.Replace that is case-insensitive? I need to search a string and replace all occurrences of %FirstName% and %PolicyAmount% with a value pulled from a database. The problem is the capitalization of FirstName varies. That prevents me from using the String.Replace() method. I've seen web pages on the subject that suggest  Regex.Replace(strInput, strToken, strReplaceWith, RegexOptions.IgnoreCase);   However for some reason when I try and replace %PolicyAmount% with $0, the replacement never takes place. I assume that it has something to do with the dollar sign being a reserved character in regex.   Is there another method I can use that doesn't involve sanitizing the input to deal with regex special characters? Single-word synonym for "immensely valuable"? I am looking for some (may be rarely know to nonnative English speakers) synonyms for  "immensely valuable" or "extremely valuable". What is a word for someone that only does something to benefit them? Take this paragraph for example: I am a follower, not a leader. Hell, I'm not even that good of a follower either, just someone who will do your bidding for the right price. Even then, if it doesn't benefit me -- or put you in debt to me -- I won't do it. Is there any way to recover deleted files which may have since been overwritten? Who owns the copyright to S[OFU] content? What with  today, possibly this is a good time to ask: who actually owns the copyright to questions, answers and comments submitted to StackOverflow and relatives?  Over in , we have the OP reaching the conclusion that SO owns the copyright and is licensing it under CC-Attribution-Sharealike, with no apparent confirmation or denial from staff, and in  we have a moderator asserting that Jeff owns the copyright to SO content.  As I note in a comment on the latter, though (which was met with deafening silence), I'm failing to find any evidence that this is the case.  I've looked for any kind of terms of service I may have agreed to indicating that I am signing over ownership of my words when I hit submit, and I can't find one.  Certainly the fact that I'm agreeing to CC-Attribution-Sharealike licensing is clear enough, but it seems to me as if I am retaining copyright while agreeing to those licensing terms, and S[OFU] is using what I have written under that license.  What's the deal?  Did I forget about something that I agreed to in the signup process (and if so, why can't I find it afterward)?  Do the owners and administrators of S[OFU] believe that they own copyright to the UGC?  Just what is going on here?  Edit as to why this matters (from answer comment thread): If I retain copyright, I can also choose to license the original content to other parties under other terms (such as using a zero-requirements license, using an attribution-required license without sharealike, etc). If SO has the copyright, I can't. iCloud Disassociation for a Mac Computer I had a Mid-2012 MacBook Pro that recently stopped booting. I narrowed this down based on troubleshooting of the boot device to likely the SATA/hard drive connector/cable no longer working for whatever reason.  I have decided to sell the system. I'd like to know if I remove the hard drive (or in this case, an after-market SSD I've installed) from the system, will there be any other data (i.e. iCloud data) stored on the system on any other chip that I can reset in any way? I plan to reset the SMC/NVRAM before I sell the system off of to someone else.  Additionally, if I remove the hard drive, is the system still associated to iCloud (specifically Find My Mac) or any other service? If so, how do I disassociate it? The system will no longer boot even if I put in my boot device.  Thanks! How can I run a command after boot? I would like to run the simple shell command echo 1 &gt; /proc/sys/kernel/sysrq at each boot, to enable the sysrq keys. When in boot should this be done, and where should I put a script to do it? Contour graphing algorithm I am not sure if this belongs on Mathematics Stack Exchange, but it is somewhat relevant here.       The Problem If you've installed any graphing/plotting apps on your smartphone, you will notice that the app will only take the equation in form of a single variable for 2D (e.g  $y=f(x)$) or in 2 variables for a 3D plot (e.g $z=f(x,y)$). This is problematic as many equations are tough to reduce to the form of $y=f(x)$ or $z=f(x,y)$. The plotters like this because this is the only way they can plot it in form of lines connecting multiple points. These plotters compute the $y$ value at fixed intervals of $x$ and join the point to the previous one. The brute force approach to counter this is to check if the function satisfies it at each point on the image. The problem is that this not only takes more time, but gives discontinuous graph for the function as the image cannot have infinite resolution.         The Question The only way to fix this is to identify which point comes after the next in the plot and join them together by a line. That is where I am stuck. How do you identify which point is sequentially the next one for a given function? Keep in mind that for a human, this might be very easy to do. But, for a computer, this requires a general algorithm. Any ideas? Sum of First $n$ Squares Equals $\frac{n(n+1)(2n+1)}{6}$ I've become very accustomed to managing service startups on Redhat/RHEL platforms using chkconfig though that doesn't appear to be the Debian/Ubuntu way - How do I update runlevel information for system services on Ubuntu?  Ultimately looking for the equivalents of:  chkconfig --add &lt;service&gt; chkconfig --level 345 &lt;service&gt; on chkconfig --del &lt;service&gt; Can I skip over releases when upgrading? I am currently using Ubuntu 10.04. I know there is a 10.10 release, but can I upgrade directly to 11.04? Could you walk me through the steps please? Why are one-way plane tickets more expensive than return tickets? Why is the second order perturbative correction to the ground state energy always down? Is this a correct way for passing an environment variable in sudo ?  sudo -u www-data -b env FOOBAR="foobar" /home/user/folder/daemon URL regex passed by regex buddy but failed by Dart Suppose an entire function $f$ is real if and only if $z$ is real. Prove that $f$ has at most $1$ zero. Let $f$ be an entire function. Suppose $f(z)$ is real if and only if $z$ is real. Prove that $f$ has at most $1$ zero. How to prove? Totally I have no idea... Please give the solution in detail since I do not understand. Origin of electric charge Baryons have charges that are the result of a polynomial calculation of their building blocks (quarks)'s fractional charges. But what gives these quarks electric charges? What interactions do they have with photons? And what about leptons, like muons and electrons? How do they get their -1 charge? And then, how do positrons and anti-muons get +1 charge? Same goes for quarks: how does up-antiquarks get -2/3 charge? Or I may want to formulate my question this way:  How does any elementary particle interact with the EM-Force to get an electric charge? I'm trying to test a page that has an input but really its a drop down list. The user enters text and then a dropdown appears based on what the user inputted. They are groups that are in the database. If I look for these elements before typing anything they dont exist but once I start typing they do exist.  The problem is I cant just type the whole name and then press enter or return because an option has to be selected from the list.  I can press arrow down to get the focus on the item from the list but then if I say enter it doesnt select, it sends that enter to the original element and nothing gets selected.  I can find the select element:  var ddList = driver.FindElement(By.CssSelector(".ui-autocomplete-input")); ddList.SendKeys("Admins");   This is the first time the list appears in the html.  It looks like this:  &lt;li class="ui-menu-item" role="presentation"&gt; The Mac editor Latexian has built in methods for compiling using latex+dvips, pdflatex and xelatex.  Furthermore, it assumes bibtex and makeindex to deal with bibliographies and indexes, respectively.  How do I customize Latexian to use, e.g. LuaTeX for compiling or Biber for bibliographies?