If there are several commands in the system that are very similar in function but cannot be deleted at will, you can use alternatives to specify a global setting.
# alternatives
usage: alternatives --install <link> <name> <path> <priority>
[--initscript <service>]
[--family <family>]
[--slave <link> <name> <path>]*
alternatives --remove <name> <path>
alternatives --auto <name>
alternatives --config <name>
alternatives --display <name>
alternatives --set <name> <path>
alternatives --list
common options: --verbose --test --help --usage --version --keep-missing
--altdir <directory> --admindir <directory>
我在目录/tools/jdk安装了java version "1.7.2_19"
# alternatives --install /usr/bin/java java /tools/jdk/bin/java 3
# alternatives --config java (设置需要版本)
