Merge pull request #454 from thecodefactory/centos7

Update README to include CentOS 7 installation instructions.

Author: evoskuil

README.md

@@ -45,6 +45,7 @@ $ sudo ldconfig     # optional
 
 Detailed instructions are provided below.
 * [Debian/Ubuntu](#debianubuntu)
+* [CentOS7](#centos-7)
 * [Macintosh](#macintosh)
 * [Windows](#windows)
 
@@ -106,6 +107,43 @@ $ sudo ./install.sh
 ```
 Libbitcoin Server is now installed in `/usr/local/bin` and can be invoked as `$ bs`.
 
+### CentOS 7
+
+Libbitcoin requires a C++11 compiler, currently minimum [GCC 4.8.0](https://gcc.gnu.org/projects/cxx0x.html) or Clang based on [LLVM 3.5](http://llvm.org/releases/3.5.0/docs/ReleaseNotes.html).
+
+Note that CentOS 7 provides an option to install Boost 1.53.0, which is older than the required version.  For this configuration, boost will be compiled by the installer.
+
+Similarly, the default installation of CentOS 7 does not provide an option to install zeromq, so it will also be compiled by the installer.
+
+To see your GCC version:
+```sh
+$ g++ --version
+```
+```
+g++ (GCC) 4.8.5 20150623 (Red Hat 4.8.5-28)
+Copyright (C) 2015 Free Software Foundation, Inc.
+This is free software; see the source for copying conditions.  There is NO
+warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+```
+If necessary, upgrade your compiler as follows:
+```sh
+$ sudo yum install gcc-c++
+```
+Next install the [build system](http://wikipedia.org/wiki/GNU_build_system) and wget, bzip2 and git:
+```sh
+$ sudo yum install autoconf automake libtool pkgconfig wget bzip2 git
+```
+Next download the [install script](https://github.com/libbitcoin/libbitcoin-server/blob/version3/install.sh) and enable execution:
+```sh
+$ wget https://raw.githubusercontent.com/libbitcoin/libbitcoin-server/version3/install.sh
+$ chmod +x install.sh
+```
+Finally install Libbitcoin Server with the following [build options](#build-notes-for-linux--macos):
+```sh
+$ sudo ./install.sh --build-zmq --build-boost
+```
+Libbitcoin Server is now installed in `/usr/local/bin` and can be invoked as `$ bs`.
+
 ### Macintosh
 
 The macOS installation differs from Linux in the installation of the compiler and packaged dependencies. Libbitcoin Server supports both [Homebrew](http://brew.sh) and [MacPorts](https://www.macports.org) package managers. Both require Apple's [Xcode](https://developer.apple.com/xcode) command line tools. Neither requires Xcode as the tools may be installed independently.

install.sh

@@ -261,8 +261,8 @@ fi
 # Set the prefix-based package config directory.
 PREFIX_PKG_CONFIG_DIR="$PREFIX/lib/pkgconfig"
 
-# Augment PKG_CONFIG_PATH search path with our prefix.
-export PKG_CONFIG_PATH="$PKG_CONFIG_PATH:$PREFIX_PKG_CONFIG_DIR"
+# Prioritize prefix package config in PKG_CONFIG_PATH search path.
+export PKG_CONFIG_PATH="$PREFIX_PKG_CONFIG_DIR:$PKG_CONFIG_PATH"
 
 # Set a package config save path that can be passed via our builds.
 with_pkgconfigdir="--with-pkgconfigdir=$PREFIX_PKG_CONFIG_DIR"