linux环境下的cat命令部分功能的简单实现，可以实现输入命令的前台运行和后台运行两种方式。-linux environment, some functions of the cat command a simple implementation, the input commands can be running in the foreground and background to run in two ways.
SHOW FULL COLUMNS FROM `jrk_downrecords` [ RunTime:0.000967s ]
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:0.068178s ]
SHOW FULL COLUMNS FROM `jrk_tagrecords` [ RunTime:0.001037s ]
SELECT * FROM `jrk_tagrecords` WHERE `status` = 1 ORDER BY `num` DESC LIMIT 20 [ RunTime:0.001239s ]
SHOW FULL COLUMNS FROM `jrk_member` [ RunTime:0.001204s ]
SELECT `id`,`username`,`userhead`,`usertime` FROM `jrk_member` WHERE `status` = 1 ORDER BY `usertime` DESC LIMIT 10 [ RunTime:0.003232s ]
SHOW FULL COLUMNS FROM `jrk_searchrecords` [ RunTime:0.001077s ]
SELECT * FROM `jrk_searchrecords` WHERE `status` = 1 ORDER BY `num` DESC LIMIT 5 [ RunTime:0.004028s ]
SELECT aid,title,count(aid) as c FROM `jrk_downrecords` GROUP BY `aid` ORDER BY `c` DESC LIMIT 10 [ RunTime:0.015154s ]
SHOW FULL COLUMNS FROM `jrk_articles` [ RunTime:0.001333s ]
UPDATE `jrk_articles` SET `hits` = 2 WHERE `id` = 293090 [ RunTime:0.018021s ]
