I have many crons that run at different intervals. I need to configure them all to not run between two specific time ranges. How can I configure a unix cron to run exclusive of 11:45-13:00 and 14:45-16:00?  If the minutes is not possible, 12:00-13:00 and 15:00 - 16:00 would suffice. Thanks!
This is a  about using cron &amp; crontab.   You have been directed here because the community is fairly sure that the answer to your question can be found below. If your question is not answered below then the answers will help you gather information that will help the community help you. This information should be edited into your original question.  The answer for 'Why is my crontab not working, and how can I troubleshoot it?' can be seen below.  This addresses the cron system with the crontab highlighted.
Find the determinant of $I + A$ I have a package (fcl) in my PPA  in my launchpad PPA and it depends on another package (libccd) which is in another PPA ppa:imnmfotmal/libccd. fcl has both build and run dependency in libccd. So i added libccd as a PPA dependency in launchpad and both are successfully build. but when i am trying to install fcl package after adding the fcl PPA, its throwing an error Reading package lists... Done Building dependency tree        Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies:  fcl : Depends: libccd but it is not installable E: Unable to correct problems, you have held broken packages.  but its successfully getting installed after adding the libccd PPA also. I want fcl to install libccd automatically without adding its PPA. how can i achieve it ?? Output of apt-cache policy fcl fcl:   Installed: (none)   Candidate: 1.0-0ppa5   Version table:      1.0-0ppa5 0         500 http://ppa.launchpad.net/imnmfotmal/fcl/ubuntu/ trusty/main amd64 Packages How to make crontab email me with output? How can I make crontab email me with the output of its jobs? I have MAILTO=redacted@yahoo.com.au above the jobs, but it doesn't work.  I know I need to use something like Postfix or Sendmail but for the life of me I cannot find out how to achieve this. I've searched and searched for a simple guide on setting up Postfix but they're all insanely complicated and expect you to be setting up a whole server to send and receive email and to know all the terms (like, what is a domain name for outgoing emails?).  All I want to do is have crontab email me. Why is this so difficult??  Additional Info:  My crontab file looks like this:  MAILTO=redacted@yahoo.com.au 1 0 * * * ~/Desktop/toskymesh.sh 59 6 * * * ~/Desktop/tooptus.sh 0 3 * * * snapraid sync   More Additional Info:  The output of ps -ef | grep '[s]endmail'  root 6840 1370 0 10:26 ? 00:00:00 sendmail: MTA: accepting connections   I know for sure cron is working, but I'm testing the mail command with echo Test | mail -s Test redacted@yahoo.com.au anyway. Given an alphabet of size $n$, how many strings of length $c$ contain every single letter of the alphabet at least once?  I first attempted to use a recurrence relation to work it out:  $$ T(c) = \left\{ \begin{array}{cr} 0 &amp;\mbox{ if $c&lt;n$} \\ n! &amp;\mbox{ if $c = n$} \\ T(c-1) \cdot n \cdot c &amp;\mbox{ if $c &gt; n$} \end{array} \right. $$  As there's no strings that contain every letter if c &lt; n, and if c = n then it's just all permutations. When c > n you can take any string of size (c-1) that contains all letters (of which there are $T(c-1)$ to choose from), you choose which letter to add (of which there are $n$ choices) and there are $c$ different positions to put it. However, this gives out results that are larger than $n^c$ (the total number of strings), so it can't be right, and I realised it was because you could count some strings multiple times, as you can make them taking different inserting steps.   Then I thought about being simpler: you choose n positions in the string, put each letter of the alphabet in one of those positions, then let the rest of the string be anything:  $$ {c\choose{n}} \cdot n! \cdot n^{c-n} $$  But again this counts strings multiple times.  I've also considered using multinomial coefficients, but as we don't know how many times each letter appears in the string it seems unlikely they would be much help. I've also tried several other methods, some complicated and some simple, but none of them seem to work.  How would you go about working out a formula for this? I'm sure there's something simple that I'm missing. How does Meta Stack Exchange work? Meta Stack Exchange seems to have different rules and user behavior than the "regular" Stack Exchange sites.  How is it different?    Individual questions answered below:                Related How to overload __init__ method based on argument type? I was getting the usual 4-8mbps in 12.04 when copying files via usb sticks. However after upgrading to 12.10, I only get 200-300kbps when I try to perform the same operation.   I have tried different usb sticks (which work flawlessly on Windows 7) and still experience the same issue. I experienced the same issue sometime ago on 11.10 but everything was normal when I upgraded to 12.04 so it might be a kernel issue.  Here's the output of dmseg |tail:      mysterio@mysterio-HP-Pavilion-dv6700-Notebook-PC:~$ dmesg |tail   [  871.023093] sdb: sdb1  [  871.026909] sd 5:0:0:0: [sdb] No Caching mode page present  [  871.026920] sd 5:0:0:0: [sdb] Assuming drive cache: write through  [  871.026927] sd 5:0:0:0: [sdb] Attached SCSI removable disk  [ 1036.226206] ISO 9660 Extensions: Microsoft Joliet Level 3  [ 1036.233561] ISO 9660 Extensions: RRIP_1991A  [ 1086.342973] ISO 9660 Extensions: Microsoft Joliet Level 3  [ 1086.343010] ISO 9660 Extensions: RRIP_1991A  [ 1173.971357] ISO 9660 Extensions: Microsoft Joliet Level 3  [ 1173.971441] ISO 9660 Extensions: RRIP_1991A   I have updated my system with the latest updates. What could be wrong? Variance of Wilcoxon Rank-Sum Test (no ties) $\newcommand{\E}[1]{\mathbb{E}\left[#1\right]} \newcommand{\r}[1]{r\left(#1\right)} \newcommand{\P}[1]{\mathbb{P}\left(#1\right)} \newcommand{\Var}[1]{\text{Var}\left[#1\right]}$  Given two sets of data $X$ with $m$ points and $Y$ with $n$ points, unioned (keeping duplicates) to create a data set $Z = \{Z_i\}$ with $m + n = N$ data points, the Wilcoxon Rank-Sum Test Statistic is given by \begin{equation*} T = \sum\limits_{i=1}^{N}r(Z_i)\cdot \mathbb{I}(Z_i \in X)\text{,} \end{equation*} where $\mathbb{I}(Z_i \in X)$ is $1$ if $Z_i \in X$, $0$ otherwise. ($r(\cdot)$ denotes the rank of the data point.)  Suppose there are no ties. Then  \begin{align*} \E{T} = \sum\limits_{i=1}^{N}\r{Z_i}\cdot \E{\mathbb{I}(Z_i \in X)} &amp;= \sum\limits_{i=1}^{N}\r{Z_i}\cdot\P{Z_i \in X} \\ &amp;= \dfrac{m}{N}\sum\limits_{i=1}^{N}\r{Z_i} \\ &amp;= \dfrac{mN(N+1)}{2N} \\ &amp;= \dfrac{m(N+1)}{2}\text{.} \end{align*} This comes out to what it says in the book Nonparametric Statistical Inference, 5th ed., by Gibbons and Chakraborti.  Now for $\Var{T}$: \begin{align*} \Var{T} &amp;= \Var{\sum\limits_{i=1}^{N}\r{Z_i}\mathbb{I}(Z_i \in X)}\\ &amp;= \sum\limits_{i=1}^{N}\left[\r{Z_i}\right]^2\Var{\mathbb{I}(Z_i \in X)} \\ &amp;= \sum\limits_{i=1}^{N}\left[\r{Z_i}\right]^2\P{Z_i \in X}\left[1-\P{Z_i \in X}\right]\\ &amp;= \left(\dfrac{m}{N}\right)\left(1-\dfrac{m}{N}\right)\sum\limits_{i=1}^{N}\left[\r{Z_i}\right]^2 \\ &amp;= \left(\dfrac{m}{N}\right)\left(1-\dfrac{m}{N}\right)\left[\dfrac{N(N+1)(2N+1)}{6}\right] \\ &amp;= \left(\dfrac{m}{N}\right)\left(\dfrac{N-m}{N}\right)\left[\dfrac{N(N+1)(2N+1)}{6}\right] \\ &amp;= \left(\dfrac{m}{N}\right)\left(\dfrac{n}{N}\right)\left[\dfrac{N(N+1)(2N+1)}{6}\right] \\ &amp;= \dfrac{2N+1}{N}\left[\dfrac{mn(N+1)}{6}\right] \end{align*} The answer should be $\dfrac{mn(N+1)}{12}$. What did I do wrong? How to run firefox and firefox ESR simultaneously The main reason I want to use firefox ESR is to use a proprietary database tool for work that only allows oracle-java based web logins for linux (or a windows only thin client). I also want to use the full version of the outlook web application which only works in firefox. I don't want to run the NPAPI plugins for normal web browsing and email.   I have the repo version of firefox installed and firefox ESR installed in /opt/firefox and linked to /usr/local/firefox-esr  When I run firefox any attempt to run firefox-esr either brings up a window without the NPAPI plugins.   If I try running with the --new-instance or --no-remote options I receive the following error:  Firefox is already running, but is not responding. To open a new window, you must first close the existing Firefox process, or restart your system.   Regardless which one I start first, I can only open that one, and get the above error if I attempt to sidestep.  What makes this an especially annoying problem is that I often have to respond to emails that I need to access the database to deal with. So either I close and open many windows. The calling thread cannot access this object because a different thread owns it In every keyboard that I have used, the keys are arranged so that the keys are staggered a small increment to the left from the previous row. Q is above and slightly to the left of A, and A is above and slightly to the left of Z. This pattern continues across the entire board. Case in point:    What is the motivation behind this design? I would think that a column layout would be easier to type on - and indeed, many ergonomic keyboards seem to go with a column layout, where Q is directly above A and so on. Is there any module or some configuration that I can define the meta tags for the views page display in drupal 7 using  3.0? Are human chromosomes connected or separate molecules? I cannot submit my answer to    I am aware that my reputation is low. Also, spam posting is discouraged.  My answer includes a compilation of Android graphing libraries, with links, so fellow hackers do not have to Google each and every one of them.  I believe this answer is superior to the current answers, because it is updated to 03/2012 and covers more than 90% of all Android charting libraries.  How can I post the answer, or how can I increase my reputation without being able to post quality answers? The old school websites included just a bunch of links to other places, I am an old man!  Alternative solution would be to blog it, and just post a link to my blog, which is not optimal. What does a "Legacy USB Mouse" option in a BIOS mean?  Yes legacy usually means older revision, or obsolete. So legacy usb mouse means support for "old style usb mouses".     That's not really answering the question. As Mr. Tamm, my high school electricity teacher, liked to say, "Yes, and oranges taste orangey."   What does legacy USB mouse support mean?   What is a legacy USB mouse?  There's an "old style" USB mouse?  What changed between what version of usb and what version of usb that made mice incompatible? Why was the change made?  When was the change made? Who made the change? What was the virtue of the "new USB mouses" over the "old USB mouses"?   Put it another way:     What is the BIOS doing when "Legacy USB Mouse" option is enabled?   What is the BIOS doing when "Legacy USB Mouse" option is disabled?   See also A list of inconveniences between quantum mechanics and (general) relativity? It is well known that quantum mechanics and (general) relativity do not fit well. I am wondering whether it is possible to make a list of contradictions or problems between them?  E.g. relativity theory uses a space-time continuum, while quantum theory uses discrete states.  I am not merely looking for a solution or rebuttal of such opposites, more for a survey of the field out of interest. How can I run everything as root I have dual booted to lubuntu (with Windows XP) and everytime and then I'm getting asked for my password. How do I run everything as root and not ask a password again? Ideally I wanted to run nginx but it has permission denied issues:  apathetic@ubuntu:~$ service nginx start Starting nginx: nginx: [alert] could not open error log file: open() "/var/log/nginx/error.log" failed (13: Permission denied) 2012/08/03 20:06:25 [warn] 4762#0: the "user" directive makes sense only if the master process runs with super-user privileges, ignored in /etc/nginx/nginx.conf:1 nginx: the configuration file /etc/nginx/nginx.conf syntax is ok 2012/08/03 20:06:25 [emerg] 4762#0: open() "/var/run/nginx.pid" failed (13: Permission denied) nginx: configuration file /etc/nginx/nginx.conf test failed Many sysv init scripts used a corresponding file in /etc/default to allow the administrator to configure it. Upstart jobs can be modified using .override files. How do I override or configure systemd units, now that systemd is the default in Ubuntu? In "Seeing like a state" of James C.Scott there is a sentence at the beginning of a paragraph (Acknowledgements xi):     There are a good many scholars whose writings opened up new   perspectives for me or provided outstanding analyses of issues that I   could not have hoped to study so comprehensively on my own.   What worries me is a good many scholars. Is this some type of inversion or ancient English? Is this grammatically right? Why is a here? I thought that appropriate version would be There are many good scholars. Am I wrong? I need help to solve following problem from Rudin's Mathematical analysis book:    Convergence of the series $\sum a_n$  implies the convergence of $\sum \dfrac{\sqrt {a_n}}{n}$, if $a_n&gt;0$  I tried to construct a suitable convergence sequence $b_n$ such that $\sum b_n$ converges and $a_n \leq b_n$ but, I am not able to find such sequence $b_n$ .  Thanks for the help and sugestions.