想要在虚拟机上的 Linux 环境下，重新搞一下 RabbitMQ 的相关实验，所以重新折腾了下如何操作：
Since RabbitMQ is written in Erlang, we need to have installed the language libraries to run the broker.
首先还是要把 Erlang 的安装搞定，最简单的方式是直接重 官网
上下载源码包或rpm包再安装，但是我是个喜欢折腾的人，所以我选择了另外一种“比较笨拙”的方式 - 即通过 Linux 系统自带的包管理工具进行安装。
按照 www.erlang-solutions.com 上的说明：
RPM-based Linux distributions RPM packages are signed. To add Erlang Solutions key to execute command:
# rpm --import http://binaries.erlang-solutions.com/debian/erlang_solutions.asc
Users of Fedora can add this file to /etc/yum.repos.d/ Users of Centos can add this file to /etc/yum.repos.d/ ( RPM Forge must be also added to repos)
其中 erlang_solutions.asc 内容如下：
-----BEGIN PGP PUBLIC KEY BLOCK-----
Version: GnuPG v1.4.10 (GNU/Linux)
mQINBE8v+uABEACgAlBUDDjc6PF7uI6mlTGnkemHF4trRINtocZKzvyKBmN+pPiV
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ctmKvzuuerI6mVQjg/80PJ4fEV0=
=VAR1
-----END PGP PUBLIC KEY BLOCK-----
其中用于 Centos 的 repo 文件内容如下：
[erlang-solutions]
name=Centos $releasever - $basearch - Erlang Solutions
baseurl=http://binaries.erlang-solutions.com/rpm/centos/$releasever/$basearch
gpgcheck=1
gpgkey=http://binaries.erlang-solutions.com/debian/erlang_solutions.asc
enabled=1
按照上面的意思，需要先安装 RepoForge ， 在 RPM Forge
上看到的内容如下：
=====================================================
RPMforge for CentOS 5
The default RPMforge repository does not replace any CentOS base packages. In the past it used to, but those packages are now in a separate repository (rpmforge-extras) which is disabled by default.
You can find a complete listing of the RPMforge package packages at http://packages.sw.be/
Download the rpmforge-release package. Choose one of the two links below, selecting to match your host's architecture. If you are unsure of which one to use you can check your architecture with the command uname -i
- i386 http://packages.sw.be/rpmforge-release/rpmforge-release-0.5.2-2.el5.rf.i386.rpm
- x86_64 http://packages.sw.be/rpmforge-release/rpmforge-release-0.5.2-2.el5.rf.x86_64.rpm
The preferred rpmforge-release package to retrieve and to install in order to enable that repository is one of the two listed above.
Install DAG's GPG key
rpm --import http://apt.sw.be/RPM-GPG-KEY.dag.txt
Verify the package you have downloaded
rpm -K rpmforge-release-0.5.2-2.el5.rf.*.rpm
Security warning: The rpmforge-release package imports GPG keys into your RPM database. As long as you have verified the md5sum of the key injection package, and trust Dag, et al., then it should be as safe as your trust of them extends.
Install the package
rpm -i rpmforge-release-0.5.2-2.el5.rf.*.rpm
This will add a yum repository config file and import the appropriate GPG keys.
Then try to install something like this
yum install htop
========================================================
首先通过 uname -i 确认了我的系统是 i386 ；通过 wget 现在对应的 rpm 包后安装，此时会在 /etc/yum.repos.d 下多出 4 个 repo ：mirrors-rpmforge、mirrors-rpmforge-extras、mirrors-rpmforge-testing 和 rpmforge.repo 。
接下来为了验证上述 repo 中确实可以找到我想安装的正确的 Erlang 版本，执行了命令 yum list|grep erlang ，结果如下：
[root@slave2 ~]# yum list|grep erlang
http://binaries.erlang-solutions.com/rpm/centos/5/i386/repodata/repomd.xml: [Errno 14] HTTP Error 404: Not Found
Trying other mirror.
Error: Cannot retrieve repository metadata (repomd.xml) for repository: erlang-solutions. Please verify its path and try again
按照错误信息的意思，应该是路径不对了，故直接在浏览器中打开上面的 http 地址，发现在只有路径 http://binaries.erlang-solutions.com/rpm/centos/6/i386/ 是存在的，而没有对应 5 的路径，坑爹啊！！可是朕不死心，重新回到 https://www.erlang-solutions.com/downloads/download-erlang-otp 上检查所有可用的 Centos 上的 Erlang 版本，结果除了一个 R14B02 32bit 版本 Erlang 是用的 Centos 5.5 的，其余全是用于 6.0 的。尼玛，难道非要我装 Centos 6.0 才行？！思来想去，直接改 repo 信息欺骗网站说自己是 6.0 版本然后安装似乎不是啥好注意，日后恐怕会惹上不必要的麻烦；重新装个 6.0 的系统太烦，毕竟已有系统中有很多东西已经配置好了；直接认栽使用 R14B02 又不甘心。唉~~华山一条路，只能源码安装了~~~（此处省略N万字）
另外，将 erlang-solutions 的 repo 去掉之后，执行 yum list|grep erlang 得到如下结果：
[root@slave2 ~]# yum list|grep erlang
ftp://ftp.oss.eznetsols.org/linux/centos/5.8/updates/i386/repodata/repomd.xml: [Errno 4] IOError: <urlopen error >
Trying other mirror.
erlang.i386 R12B-5.12.el5.rf rpmforge
erlang-doc.i386 R12B-5.12.el5.rf rpmforgerepoforge 上的 Erlang 更老，朕是与时俱进的人，果断放弃！
=================== 2012-12-10 更新 =======================
鉴于有网友说使用 EPEL 比较好，所有自己也搞了下试试：
具体操作请参考网页：
- http://www.rabbitmq.com/install-rpm.html
- http://fedoraproject.org/wiki/EPEL
- http://fedoraproject.org/wiki/EPEL/FAQ#howtouse
最后说一下结论：
就 Erlang 的包安装而言，EPEL 确实要比 repoforge 新，目前提供的最新版本为 R14B-04。这一点无论是从 repo 文件中还是直接从 http://repos.fedorapeople.org/repos/peter/erlang/epel-5/i386/ 上都可以看出。
上面都弄好后，执行 yum 命令显示，可以找到 Erlang 安装包。
[root@slave2 yum.repos.d]# yum list|grep erlang
ftp://ftp.oss.eznetsols.org/linux/centos/5.8/updates/i386/repodata/repomd.xml: [Errno 4] IOError: <urlopen error >
Trying other mirror.
erlang.i386 R14B-04.1.el5 epel-erlang
erlang-appmon.i386 R14B-04.1.el5 epel-erlang
erlang-asn1.i386 R14B-04.1.el5 epel-erlang
erlang-common_test.i386 R14B-04.1.el5 epel-erlang
erlang-compiler.i386 R14B-04.1.el5 epel-erlang
erlang-cosEvent.i386 R14B-04.1.el5 epel-erlang
erlang-cosEventDomain.i386 R14B-04.1.el5 epel-erlang
erlang-cosFileTransfer.i386 R14B-04.1.el5 epel-erlang
erlang-cosNotification.i386 R14B-04.1.el5 epel-erlang
erlang-cosProperty.i386 R14B-04.1.el5 epel-erlang
erlang-cosTime.i386 R14B-04.1.el5 epel-erlang
erlang-cosTransactions.i386 R14B-04.1.el5 epel-erlang
erlang-crypto.i386 R14B-04.1.el5 epel-erlang
erlang-debugger.i386 R14B-04.1.el5 epel-erlang
erlang-debuginfo.i386 R14B-04.1.el5 epel-erlang
erlang-dialyzer.i386 R14B-04.1.el5 epel-erlang
erlang-diameter.i386 R14B-04.1.el5 epel-erlang
erlang-doc.i386 R14B-04.1.el5 epel-erlang
erlang-docbuilder.i386 R14B-04.1.el5 epel-erlang
erlang-edoc.i386 R14B-04.1.el5 epel-erlang
erlang-erl_docgen.i386 R14B-04.1.el5 epel-erlang
erlang-erl_interface.i386 R14B-04.1.el5 epel-erlang
erlang-erts.i386 R14B-04.1.el5 epel-erlang
erlang-et.i386 R14B-04.1.el5 epel-erlang
erlang-eunit.i386 R14B-04.1.el5 epel-erlang
erlang-examples.i386 R14B-04.1.el5 epel-erlang
erlang-gs.i386 R14B-04.1.el5 epel-erlang
erlang-hipe.i386 R14B-04.1.el5 epel-erlang
erlang-ic.i386 R14B-04.1.el5 epel-erlang
erlang-inets.i386 R14B-04.1.el5 epel-erlang
erlang-inviso.i386 R14B-04.1.el5 epel-erlang
erlang-jinterface.i386 R14B-04.1.el5 epel-erlang
erlang-kernel.i386 R14B-04.1.el5 epel-erlang
erlang-megaco.i386 R14B-04.1.el5 epel-erlang
erlang-mnesia.i386 R14B-04.1.el5 epel-erlang
erlang-observer.i386 R14B-04.1.el5 epel-erlang
erlang-odbc.i386 R14B-04.1.el5 epel-erlang
erlang-orber.i386 R14B-04.1.el5 epel-erlang
erlang-os_mon.i386 R14B-04.1.el5 epel-erlang
erlang-otp_mibs.i386 R14B-04.1.el5 epel-erlang
erlang-parsetools.i386 R14B-04.1.el5 epel-erlang
erlang-percept.i386 R14B-04.1.el5 epel-erlang
erlang-pman.i386 R14B-04.1.el5 epel-erlang
erlang-public_key.i386 R14B-04.1.el5 epel-erlang
erlang-reltool.i386 R14B-04.1.el5 epel-erlang
erlang-runtime_tools.i386 R14B-04.1.el5 epel-erlang
erlang-sasl.i386 R14B-04.1.el5 epel-erlang
erlang-snmp.i386 R14B-04.1.el5 epel-erlang
erlang-ssh.i386 R14B-04.1.el5 epel-erlang
erlang-ssl.i386 R14B-04.1.el5 epel-erlang
erlang-stdlib.i386 R14B-04.1.el5 epel-erlang
erlang-syntax_tools.i386 R14B-04.1.el5 epel-erlang
erlang-test_server.i386 R14B-04.1.el5 epel-erlang
erlang-toolbar.i386 R14B-04.1.el5 epel-erlang
erlang-tools.i386 R14B-04.1.el5 epel-erlang
erlang-tv.i386 R14B-04.1.el5 epel-erlang
erlang-typer.i386 R14B-04.1.el5 epel-erlang
erlang-webtool.i386 R14B-04.1.el5 epel-erlang
erlang-wx.i386 R14B-04.1.el5 epel-erlang
erlang-xmerl.i386 R14B-04.1.el5 epel-erlang
