一、SCL
1、SCL是什麼
SCL項目主頁：https://www.softwarecollections.org/
SCL(Software Collections)可以讓你在同一個操作系統上安裝和使用多個版本的軟件，而不會影響整個系統的安裝包。
SCL爲社區的以下需求而設計：
創建和使用軟件集合生產系統、概念驗證系統、開發測試平臺。SCL目前已經支持Fedora和RHEL(衍生版本如CentOS也包含在內)。
SCL的創建就是爲了給RHEL/CentOS用戶提供一種以方便、安全地安裝和使用應用程序和運行時環境的多個(而且可能是更新的)版本的方式，同時避免把系統搞亂。與之相對的是第三方源，它們可能會在已安裝的包之間引起衝突。
現有軟件選集：
現在有以下軟件選集可供CentOS 6.5或以上版本應用
Ruby 1.9.3 (ruby193)
Python 2.7 (python27)
Python 3.3 (python33)
PHP 5.4 (php54)
Perl 5.16.3 (perl516)
Node.js 0.10 (nodejs010)
MariaDB 5.5 (mariadb55)
MySQL 5.5 (mysql55)
PostgreSQL 9.2 (postgresql92)
更多的軟件集可參看這裏：https://www.softwarecollections.org/en/scls/
2、安裝SCL
在CentOS下使用 SCL，需要安裝CentOS Software Collections。它是CentOS Extras軟件庫的一部份，並可通過以下指命進行安裝
Centos 7：
[root@Node3 ~]# yum install centos-release-scl Dependencies Resolved =================================================================================================================================== Package Arch Version Repository Size =================================================================================================================================== Installing: centos-release-scl noarch 10:7-3.el6.centos extras 12 k Installing for dependencies: centos-release-scl-rh noarch 2-3.el6.centos extras 12 k Transaction Summary =================================================================================================================================== Install 2 Package(s) [root@Node3 yum.repos.d]# rpm -ql centos-release-scl /etc/pki/rpm-gpg /etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-SIG-SCLo /etc/yum.repos.d/CentOS-SCLo-scl.repo /usr/share/doc/centos-release-scl/GPL
Centos 6：
[root@Python ~]# yum install centos-release-SCL Dependencies Resolved ============================================================================================================================================================================================ Package Arch Version Repository Size ============================================================================================================================================================================================ Installing: centos-release-scl-rh noarch 2-3.el6.centos extras 12 k Transaction Summary ============================================================================================================================================================================================ Install 1 Package(s) [root@Python yum.repos.d]# rpm -ql centos-release-scl-rh /etc/pki/rpm-gpg /etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-SIG-SCLo /etc/yum.repos.d/CentOS-SCLo-scl-rh.repo /usr/share/doc/centos-release-scl-rh/GPL
注意：Centos6和Centos7的包名是區分大小寫的！
二、SCL的設置及啓用
1、要啓用和運行SCL中的應用，你還需要安裝下列包：
[root@Python ~]# yum install scl-utils scl-utils-build
2、SCL的設置及啓用
SCL設置步驟非常簡單
[root@Python ~]# scl --help usage: scl <action> [<collection>...] <command> or: scl -l|--list [<collection>...] or: scl register <path> or: scl deregister <collection> [--force] Options: -l, --list list installed Software Collections or packages that belong to them -h, --help display this help and exit Actions: enable calls enable script from Software Collection (enables a Software Collection) <SCL script name> calls arbitrary script from a Software Collection Use '-' as <command> to read the command from standard input.
啓用一個已經安裝的SCL包
需要在每個命令中使用scl命令顯式啓用它(即想在哪條命令中使用SCL中的包，就得通過scl命令執行該命令)
$ scl enable <scl-package-name> <command>
如果想在啓用的包時執行多條命令，你可以像下面那樣創建一個啓用SCL的bash會話
$ scl enable <scl-package-name> bash
三、SCL使用實例：CentOS下安裝高版本GCC
有時編譯需要用到4.8以上版本的GCC,由於CentOS源沒有提供高版本的GCC rpm包，這時就不能通過yum方式安裝。通常的解決方案就是通過編譯安裝高版本的GCC（需要很長時間）。
這裏介紹一個更好用、更簡單的方法來升級系統GCC。
查看舊版本的GCC相關包：
[root@Python ~]# rpm -qa|grep gcc libgcc-4.4.7-18.el6.x86_64 gcc-4.4.7-18.el6.x86_64 gcc-c++-4.4.7-18.el6.x86_64 gcc-gfortran-4.4.7-18.el6.x86_64
安裝GCC 5：
[root@Python ~]# yum list|grep devtoolset|grep gcc Repository epel is listed more than once in the configuration Repository epel-debuginfo is listed more than once in the configuration Repository epel-source is listed more than once in the configuration devtoolset-3-gcc.x86_64 4.9.2-6.2.el6 centos-sclo-rh devtoolset-3-gcc-c++.x86_64 4.9.2-6.2.el6 centos-sclo-rh devtoolset-3-gcc-gfortran.x86_64 4.9.2-6.2.el6 centos-sclo-rh devtoolset-3-gcc-plugin-devel.x86_64 4.9.2-6.2.el6 centos-sclo-rh devtoolset-4-gcc.x86_64 5.3.1-6.1.el6 centos-sclo-rh devtoolset-4-gcc-c++.x86_64 5.3.1-6.1.el6 centos-sclo-rh devtoolset-4-gcc-gdb-plugin.x86_64 5.3.1-6.1.el6 centos-sclo-rh devtoolset-4-gcc-gfortran.x86_64 5.3.1-6.1.el6 centos-sclo-rh devtoolset-4-gcc-plugin-devel.x86_64 5.3.1-6.1.el6 centos-sclo-rh devtoolset-4-libgccjit.x86_64 5.3.1-6.1.el6 centos-sclo-rh devtoolset-4-libgccjit-devel.x86_64 5.3.1-6.1.el6 centos-sclo-rh devtoolset-4-libgccjit-docs.x86_64 5.3.1-6.1.el6 centos-sclo-rh devtoolset-6-gcc.x86_64 6.2.1-3.1.el6 centos-sclo-rh devtoolset-6-gcc-c++.x86_64 6.2.1-3.1.el6 centos-sclo-rh devtoolset-6-gcc-gdb-plugin.x86_64 6.2.1-3.1.el6 centos-sclo-rh devtoolset-6-gcc-gfortran.x86_64 6.2.1-3.1.el6 centos-sclo-rh devtoolset-6-gcc-plugin-devel.x86_64 6.2.1-3.1.el6 centos-sclo-rh devtoolset-6-libgccjit.x86_64 6.2.1-3.1.el6 centos-sclo-rh devtoolset-6-libgccjit-devel.x86_64 6.2.1-3.1.el6 centos-sclo-rh devtoolset-6-libgccjit-docs.x86_64 6.2.1-3.1.el6 centos-sclo-rh
在centos6.5上安裝devtoolset-3會報錯，4和6的版本不會。
[root@Python ~]# yum install devtoolset-4-gcc devtoolset-4-gcc-c++ devtoolset-4-gcc-gfortran
安裝後：
[root@Python ~]# rpm -qa|grep gcc devtoolset-4-gcc-5.3.1-6.1.el6.x86_64 libgcc-4.4.7-18.el6.x86_64 gcc-4.4.7-18.el6.x86_64 gcc-c++-4.4.7-18.el6.x86_64 devtoolset-4-gcc-c++-5.3.1-6.1.el6.x86_64 gcc-gfortran-4.4.7-18.el6.x86_64 devtoolset-4-gcc-gfortran-5.3.1-6.1.el6.x86_64
啓用高版本的GCC：
[root@Python ~]# gcc --version gcc (GCC) 4.4.7 20120313 (Red Hat 4.4.7-18) Copyright (C) 2010 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. [root@Python ~]# scl -l devtoolset-4
啓用SCL的方法：
1） scl enable 軟件包名 bash
啓用一個新的shell
[root@Python ~]# scl enable devtoolset-4 bash # 進入一個新shell [root@Python ~]# gcc --version gcc (GCC) 5.3.1 20160406 (Red Hat 5.3.1-6) 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. [root@Python ~]# c++ --version c++ (GCC) 5.3.1 20160406 (Red Hat 5.3.1-6) 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. [root@Python ~]# g++ --version g++ (GCC) 5.3.1 20160406 (Red Hat 5.3.1-6) 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.
2 ）source /opt/rh/devtoolset-4/enable
在當前shell中生效
[root@Python ~]# source /opt/rh/devtoolset-4/enable [root@Python ~]# gcc --version gcc (GCC) 5.3.1 20160406 (Red Hat 5.3.1-6) 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. [root@Python ~]# c++ --version c++ (GCC) 5.3.1 20160406 (Red Hat 5.3.1-6) 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. [root@Python ~]# g++ --version g++ (GCC) 5.3.1 20160406 (Red Hat 5.3.1-6) 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.
如果我們需要開機設置GCC 5：
[root@Python ~]# echo "source /opt/rh/devtoolset-4/enable" > /etc/profile.d/RK.sh
注意：
通過devtoolset安裝的gcc因爲沒有libstdc++包，沒有生成libstdc++庫文件，編譯或運行程序時可能會遇到
類似 /usr/lib64/libstdc++.so.6: version `GLIBCXX_3.4.21' not found 的問題
[root@Python ~]# rpm -qa|grep libstdc++ # 沒有devtoolset-4-libstdc包 libstdc++-4.4.7-18.el6.x86_64 libstdc++-devel-4.4.7-18.el6.x86_64 devtoolset-4-libstdc++-devel-5.3.1-6.1.el6.x86_64 [root@Python ~]# rpm -ql devtoolset-4-libstdc++-devel|grep libstdc++.so [root@Python ~]# rpm -ql libstdc++-devel|grep libstdc++.so [root@Python ~]# rpm -ql libstdc++|grep libstdc++.so /usr/lib64/libstdc++.so.6 /usr/lib64/libstdc++.so.6.0.13 [root@Python ~]# ls -l `rpm -ql libstdc++|grep libstdc++.so` lrwxrwxrwx 1 root root 19 Jun 7 06:46 /usr/lib64/libstdc++.so.6 -> libstdc++.so.6.0.13 -rwxr-xr-x 1 root root 987096 Mar 21 12:04 /usr/lib64/libstdc++.so.6.0.13 [root@Python ~]# find / -name "libstdc++*" /root/libstdc++-5.3.1-6.fc22.x86_64.rpm /opt/rh/devtoolset-4/root/usr/lib/gcc/x86_64-redhat-linux/5.3.1/libstdc++_nonshared.a /opt/rh/devtoolset-4/root/usr/lib/gcc/x86_64-redhat-linux/5.3.1/libstdc++.so /opt/rh/devtoolset-4/root/usr/lib/gcc/x86_64-redhat-linux/5.3.1/32/libstdc++_nonshared.a /opt/rh/devtoolset-4/root/usr/lib/gcc/x86_64-redhat-linux/5.3.1/32/libstdc++.so /opt/rh/devtoolset-4/root/usr/lib/gcc/x86_64-redhat-linux/5.3.1/32/libstdc++fs.a /opt/rh/devtoolset-4/root/usr/lib/gcc/x86_64-redhat-linux/5.3.1/32/libstdc++.a /opt/rh/devtoolset-4/root/usr/lib/gcc/x86_64-redhat-linux/5.3.1/libstdc++fs.a /opt/rh/devtoolset-4/root/usr/lib/gcc/x86_64-redhat-linux/5.3.1/libstdc++.a /usr/lib64/libstdc++.so.6 /usr/lib64/libstdc++.so.6.0.13 /usr/share/gdb/auto-load/usr/lib64/libstdc++.so.6.0.13-gdb.py /usr/share/gdb/auto-load/usr/lib64/libstdc++.so.6.0.13-gdb.pyo /usr/share/gdb/auto-load/usr/lib64/libstdc++.so.6.0.13-gdb.pyc /usr/share/gdb/auto-load/usr/lib/libstdc++.so.6.0.13-gdb.py /usr/share/gdb/auto-load/usr/lib/libstdc++.so.6.0.13-gdb.pyo /usr/share/gdb/auto-load/usr/lib/libstdc++.so.6.0.13-gdb.pyc /usr/share/doc/libstdc++-devel-4.4.7 /usr/lib/gcc/x86_64-redhat-linux/4.4.4/libstdc++.so /usr/lib/gcc/x86_64-redhat-linux/4.4.4/32/libstdc++.so /usr/lib/gcc/x86_64-redhat-linux/4.4.4/32/libstdc++.a /usr/lib/gcc/x86_64-redhat-linux/4.4.4/libstdc++.a /usr/lib/vmware-tools/lib64/libstdc++.so.6 /usr/lib/vmware-tools/lib64/libstdc++.so.6/libstdc++.so.6 /usr/lib/vmware-tools/lib32/libstdc++.so.6 /usr/lib/vmware-tools/lib32/libstdc++.so.6/libstdc++.so.6 # devtoolset安裝的gcc還是調用老的libstdc++動態庫 [root@Python ~]# vim /opt/rh/devtoolset-4/root/usr/lib/gcc/x86_64-redhat-linux/5.3.1/libstdc++.so [root@Python ~]# vim /opt/rh/devtoolset-4/root/usr/lib/gcc/x86_64-redhat-linux/5.3.1/32/libstdc++.so [root@Python ~]# strings /opt/rh/devtoolset-4/root/usr/lib/gcc/x86_64-redhat-linux/5.3.1/32/libstdc++.so /* GNU ld script Use the shared library, but some functions are only in the static library, so try that secondarily. */ OUTPUT_FORMAT(elf32-i386) INPUT ( /usr/lib/libstdc++.so.6 -lstdc++_nonshared ) [root@Python ~]# strings /opt/rh/devtoolset-4/root/usr/lib/gcc/x86_64-redhat-linux/5.3.1/libstdc++.so /* GNU ld script Use the shared library, but some functions are only in the static library, so try that secondarily. */ OUTPUT_FORMAT(elf64-x86-64) INPUT ( /usr/lib64/libstdc++.so.6 -lstdc++_nonshared )
詳見：http://xiexiaojun.blog.51cto.com/2305291/1934746