I was following a tutorial and thought why not...let me brush up on the man command...and low and behold I learned a few things after years working with different flavours of Unix.  On my RHEL7 however, trying out the new trick to be able to look-up keywords failed!  It sounds crazy, but having tried it under root and under my own username the following shows no results...now man has dozens of entries with time as a keyword...any help would be appreciated, as I think the keyword facility is very useful for and admin.  $ man -k time time: nothing appropriate.
I'm running CentOS 7.0 build 1503. I'm trying to search for commands I don't know the name of by searching the man descriptions for multiple keywords using AND (e.g. search for a command containing the both words "create" and "group" in the description).  So I came across the command apropos (which is an alias for man -k). The default behaviour when given multiple keywords is to return any command matching any of the keywords, which isn't what I want. According to the man page the option -a specifies using AND, to return matches only when all words match.  But this isn't what I'm seeing in practice, so I need some help here - e.g. using Centos 7, if I do:  apropos create user   I see a huge list of commands, seemingly matching any command with create or user in the description, as expected. Noting the list includes an entry for the command 'useradd (8) - create a new user...'.  If I do:  apropos -a create user   I only get 2 commands (environ and open). This is what I'm confused by - I would expect it to return the command 'useradd (8) - create a new user', because i can see from the previous search that command does contain those words in the description. Also the 2 returned commands don't obviously seem to be anything about creating users. What am I doing wrong? I'm sure it's something embarrassingly obvious, for that I apologise in advance.  Thanks
Problem numbering environment How do I get the size of a java.sql.ResultSet? Shouldn't this be a pretty straightforward operation? However, I see there's neither a size() nor length() method. Imaging new hard drive in Windows 7 laptop? I'm upgrading my Windows 7 laptop to a new hard drive.  How can I clone or image the old hard drive over to the new hard drive, so that it looks like nothing has changed (other than the new hard drive) to my operating system and applications?  Can I use what is built into Windows 7 Backup or should I use something else? How did Draco apparate within Hogwarts? In the season 8 episode finale of Game of Thrones the highest important lords met with Grey Worm to free      Tyrion and Jon. While it was pretty clear why they wanted to free Jon it was unclear to me why they also asked for Tyrion.   To make things even more strange, they asked about his opinion of a potential solution which becomes the actual final one in the end      (choose king and nominate someone).   I thought they (besides Sansa and Bran) don't like him and wanted to judge him? Or am I missing something? I am trying to save a GeoJSON file in QGIS as EPSG:4326, but it keeps being saved as CRS84.   EPSG:4326 and CRS84 are the same except CRS84 saves coordinates as long, lat - and EPSG:4326 saves them as lat, long.   When I open the saved file in QGIS it's read as EPSG:4326, but really the file is CRS84. I know this because when I open the GeoJSON file in notepad it's listed as CRS84, and when I load the file in Shapely it's recognized as CRS84.   What's going on here?  I've tried this on both QGIS 3.6.3 and QGIS 3.4.8 with the same result. Postfix Domain Whitelisting in Combination with Sender Authentication I'd like to whitelist several domains in my Postfix configuration in such a way that all e-mails from those domains are accepted as long as they're properly authenticated using SPF and/or DKIM, should it be used by that domain. This means that e-mails coming from those domains should not be subjected to the usual DNSBL and Greylisting process, only to a SPF and DKIM verification.  Right now I have managed to save e-mails coming from those domains from the Greylisting milter by configuring a sender_access file and using the postmap utility to convert it to a suitable hash-database.  main.cf:  ... parent_domain_matches_subdomains = yes smtpd_recipient_restrictions =   permit_mynetworks   permit_sasl_authenticated   reject_rbl_client zen.spamhaus.org   reject_unauth_destination   check_sender_access hash:/etc/postfix/sender_access   check_policy_service unix:private/tumgreyspf ...   sender_access:  domain1.com OK domain2.net OK   I've found out about  and also found a , but it appears like that is a DNSBL-only measure and is only slightly helpful in my case. How OPTIONS are settled can be an eye opener and I hope I can get some answers The only reason why I put it here is to find out whether I am a victim or just ignorant of the way brokers deal with option positions that were exercised. Whether I am a victim or just ignorant depends on the answer that I posted here. The facts are: I had a 2 SHORT QS Option at 75 which was exercised against me on the 23 Dec 00.45 AM and I later exercised my 2 LONG QS Option at 70 on 23 Dec 9.31 AM. The broker charged me Borrow Fee for 24-27 Dec for $1102, which means instead of getting $1000 profit I turn this into a loss of $102 plus comm. My question:  Since both long and short options were exercised on the same day one at 45 mins on 23 Dec and the later at 9.31 am on the same day, how can there be a SHORT POSITION in the stocks since both are net-off in my account ?  The answer I got from my broker and this is the point that I want to clarify.  The response I got from IB was that the initial exercise at 45 mins on 23 Dec was actually on 22 Dec (not 23 as I alleged). They refused to show me how they got 22 Dec.  This is my explanation to my Broker in reply.  Even if the short call and long call was exercised on different dates 22 and 23 Dec respectively, IB can only charge me for the SHORT position for one day and not from 24-27 Dec by ignoring my long call position was not there.  Further Facts:  My Broker ignored my answer and insisted the dates are correct and therefore I was charged to borrow shares that was need to satisfy the short position on exercised. So I am lost as I do not know whether the broker is correct and they can do this by ignoring my long call position after exercised or there is something they had not tell me. That is the reason I came to this site soliciting answers from those who know more than I do or had experienced the same.  I hope I have explained this clearly now and why would I want to give an opinion when I am looking for an answer ? Proof that every number ≥ $8$ can be represented by a sum of fives and threes. Can you check if my proof is right?  Theorem.  $\forall x\geq8, x$ can be represented by $5a + 3b$ where  $a,b \in \mathbb{N}$.  Base case(s): $x=8 = 3\cdot1 + 5\cdot1 \quad \checkmark\\ x=9 = 3\cdot3 + 5\cdot0 \quad \checkmark\\ x=10 = 3\cdot0 + 5\cdot2 \quad \checkmark$  Inductive step:  $n \in \mathbb{N}\\a_1 = 8, a_n = a_1 + (x-1)\cdot3\\ b_1 = 9, b_n = b_1 + (x-1)\cdot3 = a_1 +1 + (x-1) \cdot 3\\ c_1 = 10, c_n = c_1 + (x-1)\cdot3 = b_1 + 1 + (x-1) \cdot 3 = a_1 + 2 + (x-1) \cdot 3\\ \\ S = \{x\in\mathbb{N}: x \in a_{x} \lor x \in b_{x} \lor x \in c_{x}\}$  Basis stays true, because $8,9,10 \in S$  Lets assume that $x \in S$. That means $x \in a_{n} \lor x \in b_{n} \lor x \in c_{n}$.  If $x \in a_n$ then $x+1 \in b_x$,  If $x \in b_x$ then $x+1 \in c_x$,  If $x \in c_x$ then $x+1 \in a_x$.  I can't prove that but it's obvious. What do you think about this? When using the web interface, there is a favorite tags section where you can select a list of tags that you view most frequently.  This has become a cornerstone of my normal  on stack overflow, but it doesn't look like this is possible in the Android app.  There should be a mechanism by which you can add some favorite tags to the nav bar. Clicking these tags will take you to a list of similarly tagged questions.  Perhaps also the feed should include a section for each favorite tag.  These would be presented on their own, much like how "hot new questions" and "new unanswered questions" appear in the feed.  Perhaps something like this: An $n \times n$ matrix $M$ of integers has the property that $M_{ab} = M_{xy}$ iff $a+b=x+y$. How many distinct elements are there in $M$? Show that if $x$, $y$, $z$ are integers such that $x^2 + y^2 = z^2$, then at least one of them is divisible by $2$, at least one is divisible by $3$, and at least one is divisible by $5$.  I know that $x,y,z$ are sides of a right-angled triangles. If I start putting values, then I can show, but have no clue about mathematical approach.  How do I solve it mathematically, using modular arithmetic? Rewrite code to make it faster Given two functions $f$ and $g$, is there a formula for the Fourier transform of $f \circ g$ in terms of the Fourier transforms of $f$ and $g$ individually?  I know you can do this for the sum, the product and the convolution of two functions. But I haven't seen a formula for the composition of two functions. Debugging errors of SAGA interpolation algorithms in QGIS Processing? I encounter recurrent problems with the geoalgorithms that perform interpolations. No matter what technique I use I end with the following errors. As stated in the OGR tab QGIS 2.0 is unable to open a file in C drive. I have very little IT background so the message error is meaningless.   Is there anybody able to decrypt the message and solve the problem?      here this is the algorithm i used Can you explain more?  I do not know when we can use them in the sentence.  Can we use them instead of each other?     They have a beautiful home.   They have a beautiful house. I would like to see a full how-to guide on how to install Ubuntu. Find $|(\mathbb{Z} \oplus \mathbb{Z}) / \langle(3,6)\rangle|$ and determine if its cyclic Is there any bidirectional 5v-3.3v level shifter? Is there any IC that interfaces any 3.3V Input/Output to 5V Output/Input? I need it primarily for an Arduino Due but if there any bidirectional IC that works like that it would be great.  Some people advised me to use the SN74AHC125 and CD4050 ICs, but I don't understand how they work or how to interface with them. Show badges in user profile in iOS app When viewing a user's profile from the iOS app, it would be nice to be able to see what badges they have, instead of just the counts.