1、 了解系统调用pipe()的功能和实际原理
2、 编写一段程序，使用管道实现父子进程之间的通信
a) 使用系统调用fork()创建一个子进程
b) 子进程调用函数write()向父进程发送自己的进程ID和字符串” s sending a message to parent.
”。
c) 父进程调用函数read()通过管道读出子进程发来的消息，将消息输出屏幕，然后终止
SHOW FULL COLUMNS FROM `jrk_downrecords` [ RunTime:0.001014s ]
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:0.090765s ]
SHOW FULL COLUMNS FROM `jrk_tagrecords` [ RunTime:0.000968s ]
SELECT * FROM `jrk_tagrecords` WHERE `status` = 1 ORDER BY `num` DESC LIMIT 20 [ RunTime:0.001184s ]
SHOW FULL COLUMNS FROM `jrk_member` [ RunTime:0.000983s ]
SELECT `id`,`username`,`userhead`,`usertime` FROM `jrk_member` WHERE `status` = 1 ORDER BY `usertime` DESC LIMIT 10 [ RunTime:0.003323s ]
SHOW FULL COLUMNS FROM `jrk_searchrecords` [ RunTime:0.000969s ]
SELECT * FROM `jrk_searchrecords` WHERE `status` = 1 ORDER BY `num` DESC LIMIT 5 [ RunTime:0.003871s ]
SELECT aid,title,count(aid) as c FROM `jrk_downrecords` GROUP BY `aid` ORDER BY `c` DESC LIMIT 10 [ RunTime:0.017797s ]
SHOW FULL COLUMNS FROM `jrk_articles` [ RunTime:0.001277s ]
UPDATE `jrk_articles` SET `hits` = 1 WHERE `id` = 576350 [ RunTime:0.058715s ]
