使用yum安装cmake

一、搜索yum源中的CMake，查看源中最新的版本是什么，使用命令[root@localhost ~]# yum search cmake ，如果搜索出的结果过多可以配合grep命令来控制搜索结果。

[root@localhost ~]# yum search cmake
Loaded plugins: fastestmirror, refresh-packagekit, security
Loading mirror speeds from cached hostfile
 * base: mirrors.yun-idc.com
 * extras: ftp.sjtu.edu.cn
 * updates: ftp.sjtu.edu.cn
============================================== N/S Matched: cmake ================================================

 cmake-gui.i686 : Qt GUI for cmake cmake.i686 : Cross-platform make system Name and summary matches only, use "search all" for everything.
[root@localhost ~]#

二、查看yum源中的cmake版本

[root@localhost ~]# yum list cmake | grep cmake
cmake.i686              2.8.12.2-.el6               @base
[root@localhost ~]#

三、查看yum源中的cmake安装包的cmake二进制文件（即：cmake命令）安装到系统中的真实目录，安装后可以通过which或whereis命令查看。

[root@localhost ~]# yum provides */cmake
Loaded plugins: fastestmirror, refresh-packagekit, security
Loading mirror speeds from cached hostfile
 * base: mirrors..com
 * extras: mirrors..com
 * updates: mirrors..com
:kdelibs-devel-4.3.-.el6.i686 : Header files for compiling KDE  applications
Repo        : base
Matched from:
Filename    : /usr/share/kde4/apps/cmake

......

soprano-2.3.-1.2.el6.i686 : Qt wrapper API to different RDF storage solutions
Repo        : base
Matched from:
Filename    : /usr/share/soprano/cmake

cmake-2.8.12.2-.el6.i686 : Cross-platform make system
Repo        : base
Matched from:
Filename    : /usr/share/cmake/completions/cmake
Filename    : /usr/share/cmake
Filename    : /usr/bin/cmake

[root@localhost ~]#

从上面的记录可知yum源中的cmake包中的cmake命令会安装在/usr/bin目录，在yum安装jdk时javac和java等命令其实不是在/usr/bin 目录下。

执行命令 yum provides */javac 或 yum provides */java 结果如下：

[root@localhost ~]# yum provides */javac
Loaded plugins: fastestmirror, refresh-packagekit, security
Loading mirror speeds from cached hostfile
 * base: mirrors..com
 * extras: mirrors..com
 * updates: mirrors..com
:java-1.7.-openjdk-javadoc-1.7.0.99-2.6.5.1.el6.noarch : OpenJDK API Documentation
Repo        : base
Matched from:
Filename    : /usr/share/javadoc/java-1.7.-openjdk/jdk/api/javac

......

:java-1.8.-openjdk-devel-1.8.0.121-.b13.el6_8.i686 : OpenJDK Development Environment
Repo        : installed
Matched from:
Filename    : /usr/lib/jvm/java-1.8.-openjdk-1.8.0.121-.b13.el6_8.i386/bin/javac

[root@localhost ~]#

发现其实是安装到/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.121-0.b13.el6_8.i386/bin 目录下

1:java-1.8.0-openjdk-devel-1.8.0.121-0.b13.el6_8.i686 : OpenJDK Development Environment
Repo        : installed
Matched from:
Filename    : /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.121-0.b13.el6_8.i386/bin/javac

但是使用which和whereis命令查看发现是 /usr/bin目录，为啥？原因是通过alternatives映射，第五步中会有详细解释。

[root@localhost ~]# which javac
/usr/bin/javac
[root@localhost ~]# whereis javac
javac: /usr/bin/javac /usr/share/man/man1/javac.1.gz
[root@localhost ~]#

四、执行yum -y install cmake 命令安装 cmake-2.8.12.2-4

[root@localhost ~]# yum -y install cmake
Loaded plugins: fastestmirror, refresh-packagekit, security
Loading mirror speeds from cached hostfile
 * base: mirrors.yun-idc.com
 * extras: ftp.sjtu.edu.cn
 * updates: ftp.sjtu.edu.cn
Setting up Install Process
Resolving Dependencies
--> Running transaction check
---> Package cmake.i686 :2.8.12.2-.el6 will be installed
--> Finished Dependency Resolution

Dependencies Resolved

===================================================================================================================
 Package                                  Arch            Version                    Repository             Size
===================================================================================================================
Installing:
 cmake                                    i686            2.8.12.2-.el6             base                   8.0 M
Transaction Summary
===================================================================================================================

Install        Package(s)

Total download size: 8.0 M
Installed size:  M
Downloading Packages:
cmake-2.8.12.2-.el6.i686.rpm                                                                   | 8.0 MB     :
Running rpm_check_debug
Running Transaction Test
Transaction Test Succeeded
Running Transaction
  Installing : cmake-2.8.12.2-.el6.i686                                                        /
  Verifying  : cmake-2.8.12.2-.el6.i686                                                        / 

Installed:
  cmake.i686 :2.8.12.2-.el6

Complete!
[root@localhost ~]#

查看是否安装成功使用命令yum命令或rpm命令都是可以的如下：

使用yum 命令查看

[root@localhost ~]# yum list installed | grep cmake
cmake.i686                2.8.12.2-.el6  @base
[root@localhost ~]# 

已经安装成功了。

使用rpm命令查看

[root@localhost ~]# rpm -qa | grep cmake
cmake-2.8.12.2-.el6.i686
[root@localhost ~]# 

也是可以的。

五、配置环境变量，通过上面的第三步的yum provides */cmak 命令可以看到cmke命令确实是安装在 /usr/bin 目录下所以不需要独配置环境变量直接执行cmake -version 查看cmake版本，源码安装的cmake如果指定了--prefix=xxx 时是需要配置环境变量的。

[root@localhost ~]# cmake -version
cmake version 2.8.12.2
[root@localhost ~]#

也不是所有采用yum安装的程序都会可执行二进制文件都会默认安装到 /usr/bin 下，例如yum安装jdk时可执行的二进制文件或命令都放在/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.121-0.b13.el6_8.i386/bin 下，执行java -version 也是可以的，为什么？因为在alternatives中注册，在/etc/alternatives目录下会产生一些链接到/usr/lib/jvm/中刚安装好的jdk版本。

===================================================================================================================

注：因为采用yum安装jdk，系统考虑到多版本的问题，会用alternatives进行版本控制。开始，相应版本的jdk安装在/usr/lib/jvm/之后，会在alternatives中注册，在/etc/alternatives目录下会产生一些链接到/usr/lib/jvm/中刚安装好的jdk版本。链接如下：

/usr/bin/java -> /etc/alternatives/java

/etc/alternatives/java -> /usr/lib/jvm/jre-1.8.0-openjdk.i386/bin/java

为什么？

因为在/usr/bin下面会有链接到/etc/alternatives的相应的文件。通过ls -l 命令查看映射关系。使用ls命令查看文件如果查看指定文件名并且不止一个文件时ls -l [file1 file2 file3 ...]

[root@localhost bin]# ls -l  /usr/bin/java /usr/bin/javac
lrwxrwxrwx.  root root  Feb  : /usr/bin/java -> /etc/alternatives/java
lrwxrwxrwx.  root root  Feb  : /usr/bin/javac -> /etc/alternatives/javac
[root@localhost bin]# ls -l  /etc/alternatives/java /etc/alternatives/javac
lrwxrwxrwx.  root root  Feb  : /etc/alternatives/java -> /usr/lib/jvm/jre-1.8.-openjdk.i386/bin/java
lrwxrwxrwx.  root root  Feb  : /etc/alternatives/javac -> /usr/lib/jvm/java-1.8.-openjdk.i386/bin/javac
[root@localhost bin]#

根据上面的信息追踪发现/usr/bin/java 下的java二进制命令是通过alternatives映射到了/usr/lib/jvm/jre-1.8.0-openjdk.i386/bin下的java二进制文件。

这样，java命令不用设置环境变量，就可以正常运行了。但如果对于tomcat或其他软件来说还是要设置环境变量。
同样，如果安装新的版本jdk，就会重新链接到最新安装的jdk版本。当然，也可以使用alternatives修改所要使用的版本。