Linux 的最重要的特徵之一是它的为许多不同的文件系统的支持。这使其非常灵活从而与许多另外的操作系统可以很好的共存。linux采用的是树型结构。最上层是根目录，其他的所有目录都是从根目录出发而生成的。微软的DOS和windows也是采用树型结构，但是在DOS和windows中这样的树型结构的根是磁盘分区的盘符，有几个分区就有几个树型结构，他们之间的关系是并列的。但是在linux中，无论操作系统管理几个磁盘分区，这样的目录树只有一个。
SHOW FULL COLUMNS FROM `jrk_downrecords` [ RunTime:0.000958s ]
SELECT `a`.`aid`,`a`.`title`,`a`.`create_time`,`m`.`username` FROM `jrk_downrecords` `a` INNER JOIN `jrk_member` `m` ON `a`.`uid`=`m`.`id` WHERE `a`.`status` = 1 GROUP BY `a`.`aid` ORDER BY `a`.`create_time` DESC LIMIT 10 [ RunTime:0.060209s ]
SHOW FULL COLUMNS FROM `jrk_tagrecords` [ RunTime:0.001068s ]
SELECT * FROM `jrk_tagrecords` WHERE `status` = 1 ORDER BY `num` DESC LIMIT 20 [ RunTime:0.001309s ]
SHOW FULL COLUMNS FROM `jrk_member` [ RunTime:0.000960s ]
SELECT `id`,`username`,`userhead`,`usertime` FROM `jrk_member` WHERE `status` = 1 ORDER BY `usertime` DESC LIMIT 10 [ RunTime:0.003296s ]
SHOW FULL COLUMNS FROM `jrk_searchrecords` [ RunTime:0.000767s ]
SELECT * FROM `jrk_searchrecords` WHERE `status` = 1 ORDER BY `num` DESC LIMIT 5 [ RunTime:0.003680s ]
SELECT aid,title,count(aid) as c FROM `jrk_downrecords` GROUP BY `aid` ORDER BY `c` DESC LIMIT 10 [ RunTime:0.023355s ]
SHOW FULL COLUMNS FROM `jrk_articles` [ RunTime:0.008850s ]
UPDATE `jrk_articles` SET `hits` = 1 WHERE `id` = 580197 [ RunTime:0.020969s ]
