请问下，文件系统里的BIN ETC USR等等这些文件夹有什么用？
一般下载好的东西，安装好的东西分别装在哪的？
如果有命令，请问命令是什么？

请通俗易懂的介绍下。。。我刚接触这个。。。
谢谢！！！

# dpkg -L firefox-3.0
/.
/usr
/usr/lib
/usr/lib/firefox-addons
/usr/lib/firefox-addons/extensions
/usr/lib/firefox-addons/plugins
/usr/lib/firefox-addons/searchplugins
/usr/lib/firefox-addons/searchplugins/amazondotcom.xml
/usr/lib/firefox-addons/searchplugins/answers.xml
/usr/lib/firefox-addons/searchplugins/creativecommons.xml
/usr/lib/firefox-addons/searchplugins/eBay.xml
/usr/lib/firefox-addons/searchplugins/google.xml
/usr/lib/firefox-addons/searchplugins/wikipedia.xml
/usr/lib/firefox-addons/searchplugins/yahoo.xml
/usr/lib/firefox-addons/searchplugins/debsearch.gif
/usr/lib/firefox-addons/searchplugins/debsearch.src
/usr/lib/firefox-3.0.1
/usr/lib/firefox-3.0.1/components
/usr/lib/firefox-3.0.1/components/aboutRobots.js
/usr/lib/firefox-3.0.1/components/FeedConverter.js
/usr/lib/firefox-3.0.1/components/FeedWriter.js
/usr/lib/firefox-3.0.1/components/fuelApplication.js
/usr/lib/firefox-3.0.1/components/nsBrowserContentHandler.js
/usr/lib/firefox-3.0.1/components/nsBrowserGlue.js
/usr/lib/firefox-3.0.1/components/nsMicrosummaryService.js
/usr/lib/firefox-3.0.1/components/nsPlacesTransactionsService.js
/usr/lib/firefox-3.0.1/components/nsSafebrowsingApplication.js
/usr/lib/firefox-3.0.1/components/nsSearchService.js
/usr/lib/firefox-3.0.1/components/nsSearchSuggestions.js
/usr/lib/firefox-3.0.1/components/nsSessionStartup.js
/usr/lib/firefox-3.0.1/components/nsSessionStore.js
/usr/lib/firefox-3.0.1/components/nsSetDefaultBrowser.js
/usr/lib/firefox-3.0.1/components/nsSidebar.js
/usr/lib/firefox-3.0.1/components/WebContentConverter.js
/usr/lib/firefox-3.0.1/components/browser.xpt
/usr/lib/firefox-3.0.1/components/libbrowsercomps.so
/usr/lib/firefox-3.0.1/components/libbrowserdirprovider.so
/usr/lib/firefox-3.0.1/modules
/usr/lib/firefox-3.0.1/modules/distribution.js
/usr/lib/firefox-3.0.1/firefox
/usr/lib/firefox-3.0.1/run-mozilla.sh
/usr/lib/firefox-3.0.1/defaults
/usr/lib/firefox-3.0.1/defaults/preferences
/usr/lib/firefox-3.0.1/defaults/preferences/firefox-l10n.js
/usr/lib/firefox-3.0.1/defaults/preferences/firefox.js
/usr/lib/firefox-3.0.1/defaults/preferences/firefox-branding.js
/usr/lib/firefox-3.0.1/defaults/preferences/channel-prefs.js
/usr/lib/firefox-3.0.1/defaults/preferences/ubuntu-useragent.js
/usr/lib/firefox-3.0.1/icons
/usr/lib/firefox-3.0.1/icons/mozicon16.xpm
/usr/lib/firefox-3.0.1/icons/mozicon50.xpm
/usr/lib/firefox-3.0.1/icons/document.png
/usr/lib/firefox-3.0.1/icons/mozicon128.png
/usr/lib/firefox-3.0.1/chrome
/usr/lib/firefox-3.0.1/chrome/en-US.jar
/usr/lib/firefox-3.0.1/chrome/en-US.manifest
/usr/lib/firefox-3.0.1/chrome/browser.jar
/usr/lib/firefox-3.0.1/chrome/browser.manifest
/usr/lib/firefox-3.0.1/chrome/classic.jar
/usr/lib/firefox-3.0.1/chrome/classic.manifest
/usr/lib/firefox-3.0.1/chrome/icons
/usr/lib/firefox-3.0.1/chrome/icons/default
/usr/lib/firefox-3.0.1/chrome/icons/default/default16.png
/usr/lib/firefox-3.0.1/chrome/icons/default/default32.png
/usr/lib/firefox-3.0.1/chrome/icons/default/default48.png
/usr/lib/firefox-3.0.1/browserconfig.properties
/usr/lib/firefox-3.0.1/blocklist.xml
/usr/lib/firefox-3.0.1/application.ini
/usr/lib/firefox-3.0.1/.autoreg
/usr/lib/firefox-3.0.1/firefox.sh
/usr/lib/firefox-3.0.1/firefox-3.0-restart-required.update-notifier
/usr/lib/firefox-3.0.1/ffox-3-beta-profile-migration-dialog
/usr/lib/xulrunner-addons
/usr/lib/xulrunner-addons/extensions
/usr/lib/xulrunner-addons/extensions/{972ce4c6-7e08-4474-a285-3208198ce6fd}
/usr/lib/xulrunner-addons/extensions/{972ce4c6-7e08-4474-a285-3208198ce6fd}/install.rdf
/usr/share
/usr/share/doc
/usr/share/doc/firefox-3.0
/usr/share/doc/firefox-3.0/copyright
/usr/share/doc/firefox-3.0/firefox.cfg
/usr/share/doc/firefox-3.0/MPL.gz
/usr/share/doc/firefox-3.0/changelog.Debian.gz
/usr/share/menu
/usr/share/menu/firefox-3.0
/usr/share/applications
/usr/share/applications/firefox.desktop
/usr/share/bug
/usr/share/bug/firefox-3.0
/usr/share/bug/firefox-3.0/presubj
/usr/share/apport
/usr/share/apport/package-hooks
/usr/share/apport/package-hooks/firefox-3.0.py
/usr/share/pixmaps
/usr/bin
/etc
/etc/firefox-3.0
/etc/firefox-3.0/profile
/etc/firefox-3.0/profile/bookmarks.html
/etc/firefox-3.0/profile/localstore.rdf
/etc/firefox-3.0/profile/prefs.js
/etc/firefox-3.0/profile/mimeTypes.rdf
/etc/firefox-3.0/profile/chrome
/etc/firefox-3.0/profile/chrome/userChrome-example.css
/etc/firefox-3.0/profile/chrome/userContent-example.css
/etc/firefox-3.0/pref
/etc/firefox-3.0/pref/firefox.js
/usr/lib/firefox-3.0.1/defaults/syspref
/usr/lib/firefox-3.0.1/defaults/profile
/usr/lib/firefox-3.0.1/extensions
/usr/lib/firefox-3.0.1/plugins
/usr/lib/firefox-3.0.1/searchplugins
/usr/lib/firefox-3.0.1/dictionaries
/usr/share/pixmaps/firefox-3.0.png
/usr/bin/firefox
/usr/bin/firefox-3.0

知道安装好的软件都放到哪里了没？

就是在USR下的吗？

usr是一般用户自己安装的软件的位置
bin为大部分管理软件和系统程序的位置
etc是放配置文件的
另外
opt目录也常用来安装用户自己的软件