可替换系统（alternatives system）的应用浅议

[root@BlueSkytv2. 0 ]#java
Usage:gij[OPTION]...CLASS[ARGS]...
toinvokeCLASS.main,or
gij - jar[OPTION]...JARFILE[ARGS]...
toexecuteajarfile
Try`gij -- help ' formoreinformation.

[root@BlueSkytv2. 0 ]#whichjava
/ usr / bin / java
[root@BlueSkysoftware]#ls / usr / bin / java - l
lrwxrwxrwx 1 rootroot 22 01 - 15 21 : 23 / usr / bin / java -> / etc / alternatives / java
[root@BlueSkysoftware]#ll / etc / alternatives / java
lrwxrwxrwx 1 rootroot 35 05 - 10 13 : 48 / etc / alternatives / java -> / usr / lib / jvm / jre - 1.4 . 2 - gcj / bin / java

[root@BlueSkysoftware]#alternatives -- help
替换选择(alternatives)的版本 1.3 . 30 - 版权(C) 1997 - 2000 RedHat,Inc.
在GNU公共许可的条款下，本软件可以被自由发行。

用法：alternatives -- install link > name > path > priority >
[ -- initscript service > ]
[ -- slave link > name > path > ] *
alternatives -- remove name > path >
alternatives -- auto name >
alternatives -- config name >
alternatives -- display name >
alternatives -- set name > path >

公用选项： -- verbose -- test -- help -- usage -- version
-- altdir directory > -- admindir directory >

[root@BlueSkysoftware]#rpm - ivhjre - 1_5_0_09 - linux - i586.rpm
Preparing...###########################################[ 100 % ]
1 :jre###########################################[ 100 % ]

[root@BlueSkysoftware]# / usr / java / jre1. 5 .0_09 / bin / java
Usage:java[ - options] class [args...]
(toexecutea class )
orjava[ - options] - jarjarfile[args...]
(toexecuteajarfile)

where optionsinclude:
- d32usea 32 - bitdatamodel if available

- d64usea 64 - bitdatamodel if available
- clienttoselectthe " client " VM
- servertoselectthe " server " VM
- hotspot is asynonym for the " client " VM[deprecated]
The default VM is client.

- cp class searchpathofdirectoriesandzip / jarfiles >
- classpath class searchpathofdirectoriesandzip / jarfiles >
A:separatedlistofdirectories,JARarchives,
andZIParchivestosearch for class files.
- D name >= value >
set asystemproperty
- verbose[: class | gc | jni]
enableverboseoutput
- versionprintproductversionandexit
- version: value >
requirethespecifiedversiontorun
- showversionprintproductversionand continue
- jre - restrict - search | - jre - no - restrict - search
include / excludeuser private JREs in theversionsearch
-? - helpprint this helpmessage
- Xprinthelponnon - standardoptions
- ea[: packagename > ... | : classname > ]
- enableassertions[: packagename > ... | : classname > ]
enableassertions
- da[: packagename > ... | : classname > ]
- disableassertions[: packagename > ... | : classname > ]
disableassertions
- esa | - enablesystemassertions
enablesystemassertions
- dsa | - disablesystemassertions
disablesystemassertions
- agentlib: libname > [ = options > ]
loadnativeagentlibrary libname > ,e.g. - agentlib:hprof
seealso, - agentlib:jdwp = helpand - agentlib:hprof = help
- agentpath: pathname > [ = options > ]
loadnativeagentlibrarybyfullpathname
- javaagent: jarpath > [ = options > ]
loadJavaprogramminglanguageagent,seejava.lang.instrument

[root@BlueSkysoftware]#alternatives -- install / usr / bin / javajava / usr / java / jre1. 5 .0_09 / bin / java 300

[root@BlueSkysoftware]#alternatives -- configjava

共有 2 个程序提供“java”。

选择命令
-----------------------------------------------
* 1 / usr / lib / jvm / jre - 1.4 . 2 - gcj / bin / java
2 / usr / java / jre1. 5 .0_09 / bin / java

按Enter来保存当前选择[ + ]，或键入选择号码： 2
[root@BlueSkysoftware]#java
Usage:java[ - options] class [args...]
(toexecutea class )
orjava[ - options] - jarjarfile[args...]
(toexecuteajarfile)

where optionsinclude:
- d32usea 32 - bitdatamodel if available

- d64usea 64 - bitdatamodel if available
- clienttoselectthe " client " VM
- servertoselectthe " server " VM
- hotspot is asynonym for the " client " VM[deprecated]
The default VM is client.

- cp class searchpathofdirectoriesandzip / jarfiles >
- classpath class searchpathofdirectoriesandzip / jarfiles >
A:separatedlistofdirectories,JARarchives,
andZIParchivestosearch for class files.
- D name >= value >
set asystemproperty
- verbose[: class | gc | jni]
enableverboseoutput
- versionprintproductversionandexit
- version: value >
requirethespecifiedversiontorun
- showversionprintproductversionand continue
- jre - restrict - search | - jre - no - restrict - search
include / excludeuser private JREs in theversionsearch
-? - helpprint this helpmessage
- Xprinthelponnon - standardoptions
- ea[: packagename > ... | : classname > ]
- enableassertions[: packagename > ... | : classname > ]
enableassertions
- da[: packagename > ... | : classname > ]
- disableassertions[: packagename > ... | : classname > ]
disableassertions
- esa | - enablesystemassertions
enablesystemassertions
- dsa | - disablesystemassertions
disablesystemassertions
- agentlib: libname > [ = options > ]
loadnativeagentlibrary libname > ,e.g. - agentlib:hprof
seealso, - agentlib:jdwp = helpand - agentlib:hprof = help
- agentpath: pathname > [ = options > ]
loadnativeagentlibrarybyfullpathname
- javaagent: jarpath > [ = options > ]
loadJavaprogramminglanguageagent,seejava.lang.instrument

[root@BlueSkysoftware]#alternatives -- displayjava
java - 状态是手工。
链接目前指向 / usr / java / jre1. 5 .0_09 / bin / java
/ usr / lib / jvm / jre - 1.4 . 2 - gcj / bin / java - 优先度 1420
从keytool： / usr / lib / jvm / jre - 1.4 . 2 - gcj / bin / keytool
从rmiregistry： / usr / lib / jvm / jre - 1.4 . 2 - gcj / bin / rmiregistry
从jre_exports： / usr / lib / jvm - exports / jre - 1.4 . 2 - gcj
从jre： / usr / lib / jvm / jre - 1.4 . 2 - gcj
/ usr / java / jre1. 5 .0_09 / bin / java - 优先度 300
从keytool：( null )
从rmiregistry：( null )
从jre_exports：( null )
从jre：( null )
当前“最佳”版本是 / usr / lib / jvm / jre - 1.4 . 2 - gcj / bin / java。