I have a large IMAP email account which contains many emails in a rich structure of directories. How to back up the whole IMAP account to my local computer? The requirements: Automatically downloading these files. There are many directories, and copying-pasting emails will take too much time. Keep the directory structures which are used to…
I use Emacs in consoles and start Emacs frequently (like check a file, edit it, close it and loop). However, Emacs seems take some time to start up especially some modes/extensions are used. How to make Emacs start up faster? I summarize my solution at this post: Making Emacs Startup Faster. The key is to…
I share a ADSL modem via a Wifi router with several roommates. Sometimes, I find the network bandwidth left is too little. Suspiciously, some one is using BT, Thunder, eMule or other P2P tools. These tools can easily use up all the bandwidth and left little for others. How to prevent some roommates from hogging…
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utop is an improved toplevel for OCaml supporting line edition, history, real-time and context sensitive completion, colors and etc. utop is convenient to use. However, the key bindings are a little bit different from the ones with GNU readline. What are all the key bindings? The #utop_bindings command will print all the key bindings. Here…
This is the scenario: I want to remove a old hard disk which is a LVM PV and contains data. There is free space available on other PVs in the VG. It should move the data from the disk to be removed to other PVs and then remove the disk. The process to remove sdb…
How to convert seconds since the epoch (1970-01-01 UTC) to a date in Linux? For example, Convert the time stamp 1349361711.169942 to Thu Oct 4 22:41:51 HKT 2012 You can use the date command on Linux to convert the time formats. For converting the time stamp 1349361711.169942 to the normal data format: $ date -d…
I have a “t_form” table and a “t_attribute” table. It looks a little bit like below. Form table form_id | form_name | description ———————————– 1 | Laptop | Possible attributes are Model, Screen Size, OS, Cd Player 2 | Mobile | Possible attributes are Model, OS 3 | Tablet | Possible attributes are Model, Screen…
I have seen the question Better way to count total page views? I think, the better way is.. We can save the number of page views in the database. It is acceptable. But, it is not fulfilling my requirement, if many different users can appear to have the same IP Address (e.g, if they are…
With Gnome 3, I try to start a vncserver with $ vncserver -geometry 1024×768 to start a vnc server with geometry 1024×768, which works well with Gnome 2 before. This also works for twm. However, after I connect to the vnc server, the resolution is not 1024×768. I change the geometry to other resolution and…
I see this message in the error log of httpd: PHP Fatal error: Maximum execution time of 30 seconds exceeded in and PHP Fatal error: Allowed memory size of 268435456 bytes exhausted How to change them to a longer and larger value? To change the allowed maximum memory usage of PHP: Set memory_limit = 256M…
This tutorial introduces how to install Scala 2.9.2 on 64-bit Fedora Linux 17. There are some changes needed to make scala work on Fedora Linux 17. Please check it out in the answer. Install Java Scala depends on Java, so please install Java first. In this tutorial, we installed JDK to: /usr/java/jdk1.6.0_24/lib/. Install Scala from…
There is a “Include full text in feeds:” option in the “RSS feeds” configuration panel but no options/method to only show excerpt instead of the “full text” or nothing for RSS feeds. This need to hack the question2answer source code. Details are in the answer. The changes based on Question2asnwer 1.5.4: diff –git a/qa-include/qa-index.php b/qa-include/qa-index.php…
I frequently hear that cin is significantly slower than scanf in C++. Is this true? And how to improve the efficiency of cin? It is really nice to use most of time. One discussion about that cin is very slow is here: http://apps.topcoder.com/forums/?module=Thread&threadID=508058&start=0&mc=7 In short: cin is not always slower (can be faster actually, see…
How to restore a Gnome 3 session? Which means: opening all the programs running last time when I log out in Gnome 3. If your purpose is to automatically start programs after logging in Gnome, another possible method is using the autostart script: https://www.systutorials.com/qa/119/how-to-write-a-autostart-script-for-gnome Run gnome-session-properties. In the “Options” tab, select “Automatically remember running applications…
What are the SQL layer solution over NoSQL databases such as key/value stores? Phoenix: A SQL layer on HBase: https://github.com/forcedotcom/phoenix They also show some performance results: https://github.com/forcedotcom/phoenix/wiki/Performance F1 – The Fault-Tolerant Distributed RDBMS Supporting Google’s Ad Business: http://research.google.com/pubs/pub38125.html With F1, we have built a novel hybrid system that combines the scalability, fault tolerance, transparent sharding,…
How To Find Out When Photos in The iPhone Were Taken? The default viewer in iPhone seems do not show these information. The iPhone has no native mechanism to see the photo taken date information. However there is the information. You need a 3’rd party application to view the EXIF data (time taken, GPS coordinates,…
On Linux (Fedora 17 x86-64), Chrome keeps reporting “Adobe Flash Player was blocked because it is out of date.” every time I browse a page that contains Flash. How to fix this? I did this and it turned to be working for me: Disable the libpepflashplayer in Chrome by run chrome://plugins/ in the URL bar….
I merge a branch, say b1, from another branch, say b2. Both b1 and b2 have some commits. Say, b1: c1 —> c2 —> c3 b2: c1 —> c4 —> c5 Now, if I merge b2 to b1 and there is no conflicts, b1’s history includes b2’s commits (c4, c5). How to revert this merge…
I made some changes to /etc/sysctl.conf. I know it will take effect next time Linux boots. However, how to make the changes to sysctl.conf take effect without rebooting Linux? You can force Linux to reload the new configuration in /etc/sysctl.conf by: execute the following command as root: sysctl -p For more details, check the manual…