Cache

how to remove specific directories recursively

ByWeiwei Jia

How to remove .svn directories under hlfs dir recursively as follows. weiwei@weiwei-HP-Compaq-dx6128-MT-PX478AV:~/workshop1/hlfs > find ./ -name “.svn” ./test/build/.svn ./test/.svn ./output/conf/.svn ./output/lib32/.svn ./patches/.svn ./src/include/.svn ./src/include/api/.svn ./src/snapshot/.svn ./src/snapshot/unittest/build/.svn ./src/snapshot/unittest/.svn ./src/utils/.svn ./src/clean/Mapreducer/build/.svn ./src/clean/Mapreducer/.svn ./src/clean/.svn ./src/clean/unittest/.svn ./src/icache/.svn ./src/icache/unittest/.svn ./src/backend/.svn ./src/storage/.svn ./src/cache/.svn ./src/cache/unittest/.svn ./src/clone/.svn ./src/tools/.svn ./src/tools/unittest/.svn ./src/logger/.svn weiwei@weiwei-HP-Compaq-dx6128-MT-PX478AV:~/workshop1/hlfs > find ./ -name “.svn” | xargs rm -rf

How to get logs of a specific time range on Linux?

ByEric Ma

The logs I am processing is Hadoop log (log4j). It is in format like: 2014-09-20 21:55:11,855 INFO org.apache.hadoop.nfs.nfs3.IdUserGroup: Updated user map size: 36 2014-09-20 21:55:11,863 INFO org.apache.hadoop.nfs.nfs3.IdUserGroup: Updated group map size: 55 2014-09-20 22:10:11,907 INFO org.apache.hadoop.nfs.nfs3.IdUserGroup: Update cache now 2014-09-20 22:10:11,907 INFO org.apache.hadoop.nfs.nfs3.IdUserGroup: Not doing static UID/GID mapping because ‘/etc/nfs.map’ does not exist. Now, I…

Finding All Available Versions of a Package in Ubuntu

ByEric Ma

How to find all available versions of a package in Ubuntu? To list available versions of a package: apt-cache showpkg <package-name> For example, to check all versions of thunderbird: $ sudo apt-cache showpkg thunderbird Package: thunderbird Versions: 1:31.1.1+build1-0ubuntu0.14.04.1 (/var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_trusty-updates_main_binary-amd64_Packages) (/var/lib/apt/lists/security.ubuntu.com_ubuntu_dists_trusty-security_main_binary-amd64_Packages) Description Language: File: /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_trusty_main_binary-amd64_Packages MD5: 68ed1001b79d708ad48956a0c129114d Description Language: en File: /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_trusty_main_i18n_Translation-en MD5: 68ed1001b79d708ad48956a0c129114d 1:31.0+build1-0ubuntu0.14.04.1 (/var/lib/dpkg/status)…

How to install Adobe Reader on Linux Mint 17?

ByEric Ma

How to install Adobe Reader on Linux Mint 17? First, add Canonical PPA repository sudo add-apt-repository “deb http://archive.canonical.com/ precise partner” Then, update apt cache and install Adobe Reader sudo aptitude update sudo aptitude install acroread You can select “Yes” to set Adobe Reader as the default PDF viewer or “No” to not set it. E.Z.M.,…

Cache at Facebook

ByQ A

About caching system at Facebook. According to: https://www.facebook.com/notes/facebook-engineering/monitoring-cache-with-claspin/10151076705703920 Facebook has two major cache systems: Memcache, which is a simple lookaside cache with most of its smarts in the client, and TAO, a caching graph database that does its own queries to MySQL. The NSDI’13 paper introduces more about Memcache: https://www.usenix.org/conference/nsdi13/scaling-memcache-facebook The USENIX ATC’13 paper introduces…

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Synchronizing home directories

ByQ A

Any good tools to synchronize home directories on Linux boxes? Many have several PC/laptops and consequently many home directories. There is home directory synchronizing problem. unison is a good tool to do this: http://www.cis.upenn.edu/~bcpierce/unison/download/releases/stable/unison-manual.html#rshmeth http://www.watzmann.net/blog/2009/02/my-homedirs-in-unison.html http://www.cis.upenn.edu/~bcpierce/papers/index.shtml#File%20Synchronization Useful script: $ unison -batch -ui text ./ /mnt/homebak/zma/ In text user interface, synchronizing two directories in batch mode…

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Where Does Evolution Save Its Data and Configuration Files on Linux?

ByEric Ma

Evolution is a great personal information management tool that provides Email, address book and calendar tools. Evolution provides many enterprise friendly feature such as native support to Microsoft Exchange connectivity for Emails, address books and calendars. Evolution uses various ways including plain files and dconf configuration systems. This post will give an introduction to the…

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Hadoop Installation Tutorial (Hadoop 2.x)

ByEric Ma

Hadoop 2 or YARN is the new version of Hadoop. It adds the yarn resource manager in addition to the HDFS and MapReduce components. Hadoop MapReduce is a programming model and software framework for writing applications, which is an open-source variant of MapReduce designed and implemented by Google initially for processing and generating large data…

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Improving Fedora Font Rendering with Open Software and Fonts Only

ByEric Ma

It is continuously discussed that some Fedora users do not like the font rendering in Fedora Linux and there are solutions to improve the font rendering with potentially non-free or non-licensed software/fonts. However, with only the open source fonts and software and little tricks, the font rendering on Fedora can be quite good. In this…

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Accelerating WordPress with WP Super Cache, Opcache and Autoptimize

ByEric Ma

WordPress can be very fast after some effort on performance optimization with the help from its plenty of plugins. Possible ways include using cache to cut down the number of database queries, improves HTML/JavaScript/CSS code, and optimizing PHP’s performance with opcode cache. In this post, we introduce how to speed up WordPress with OPcache, page…

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Software Engineering Advice from Building Large-Scale Distributed Systems by Jeff Dean

ByEric Ma

Software Engineering Advice from Building Large-Scale Distributed Systems by Jeff Dean. You can download the slides from Software Engineering Advice from Building Large-Scale Distributed Systems by Jeff Dean. These slides contain the “Numbers everyone should know” which everyone working on systems should be familiar with. Numbers Everyone Should Know L1 cache reference 0.5 ns Branch…