程序目的：若在5.5秒前按下回车则输出主目录下的所有文件，若没有任何动作，则输出CPU运行状况，并且能够kill掉最占CPU的进程
程序分析：参考书本《linux软件工程师实用教程》P196页程序可以实现程序时间上的控制，输出目录则可以调用scandir函数，shell命令top用来监察CPU使用状况，按下<k>+pid则可以kill掉进程
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
#include <stdio.h>
#include <dirent.h>
#include <stdlib.h>
#include <time.h>
#define STDIN 0
int main()
{
struct timeval tv;
fd_set readfds;
DIR * dir;
struct dirent **namelist;
int i;
time_t t;
tv.tv_sec=5;
tv.tv_usec=500000;
t=time(0);
printf("%s",asctime(localtime(&t)));
FD_CLR(STDIN,&readfds);
FD_ZERO(&readfds);
FD_SET(STDIN, &readfds);
select(STDIN+1,&readfds,NULL,NULL,&tv);
if (FD_ISSET(STDIN,&readfds))
{
t=time(0);
printf("%s ",asctime(localtime(&t)));
i=scandir("/home/king",&namelist,0,alphasort);
while(i--)
{
printf("%s ",namelist[i]->d_name);
}
free(namelist);
}
else
{
t=time(0);
printf("%s ",asctime(localtime(&t)));
system("top");
}
}
运行结果：
king@ubuntu:~$ ./4
Sat Sep 11 17:15:45 2010
Sat Sep 11 17:15:48 2010
通讯录1.1.xlsx 求否工作流程.pdf user.log toolset tickets terminallock temp project.txt main mail.log ipv6 hello gedit.log fifo2 fifo1 examples.desktop example.log example.c example edit checktime.c checktime Videos Ubuntu One Templates Public Pictures Music GNUstep Downloads Documents Desktop 6-4.c 6-4 402.c 402 401.c 401 4.c 4-9file 4-9.c 4-9 4-8file 4-8.c 4-8 4-7test 4-7.c 4-7 4-6file 4-6.c 4-6 4-5.c 4-5 4-4.c 4-4 4-3.c 4-3 4-2.c 4-2 4-10.c 4-1.c 4-1 4-01.c 4-01 4 3.c 3-9.c 3-9 3-8.c 3-8-1.c 3-8-1 3-8 3-7.c 3-7 3-6.c 3-6 3-4.c 3-4 3-3.c 3-3-1.c 3-3-1 3-3 3-13.c 3-12.c 3-12 3-11.c 3-11 3-10.c 3-10 3 2.c 2-0.c 2 1.c 1 .xsession-errors.old .xsession-errors .xinput.d .xine .wine .viminfo .update-notifier .thumbnails .themes .tencent .sudoku .sudo_as_admin_successful .stardict .recently-used.xbel .pulse-cookie .pulse .profile .openoffice.org .nautilus .mozilla .mission-control .macromedia .local .kk.c.swp .kde .icons .gvfs .gtk-bookmarks .gstreamer-0.10 .google .gnome2_private .gnome2 .gksu.lock .gimp-2.6 .gegl-0.0 .gconfd .gconf .fonts.conf .fontconfig .face .evolution .esd_auth .emacs.d .emacs .easytag .dmrc .dbus .config .compiz .cache .bashrc .bash_logout .bash_history .adobe .ICEauthority .Fontmatrix .3.c.swp .. . king@ubuntu:~$
king@ubuntu:~$ ./4
Sat Sep 11 17:17:13 2010
Sat Sep 11 17:17:19 2010
top - 17:17:19 up 7:51, 3 users, load average: 0.44, 0.38, 0.39
Tasks: 212 total, 2 running, 199 sleeping, 11 stopped, 0 zombie
Cpu(s): 9.5%us, 2.3%sy, 0.1%ni, 87.1%id, 0.7%wa, 0.1%hi, 0.2%si, 0.0%st
Mem: 2058932k total, 1994332k used, 64600k free, 466260k buffers
Swap: 261112k total, 4284k used, 256828k free, 486084k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
7198 king 20 0 2544 1140 812 R 4 0.1 0:00.02 top
1016 root 20 0 184m 126m 24m S 2 6.3 19:50.37 Xorg
1787 king 20 0 407m 97m 20m S 2 4.9 53:29.51 firefox-bin
1897 king 20 0 31820 16m 2664 S 2 0.8 0:42.93 ubuntuone-syncd
1 root 20 0 2800 1380 1012 S 0 0.1 0:00.43 init
2 root 20 0 0 0 0 S 0 0.0 0:00.00 kthreadd
3 root RT 0 0 0 0 S 0 0.0 0:00.00 migration/0
4 root 20 0 0 0 0 S 0 0.0 0:00.53 ksoftirqd/0
5 root RT 0 0 0 0 S 0 0.0 0:00.00 watchdog/0
6 root RT 0 0 0 0 S 0 0.0 0:00.00 migration/1
7 root 20 0 0 0 0 S 0 0.0 0:00.87 ksoftirqd/1
8 root RT 0 0 0 0 S 0 0.0 0:00.00 watchdog/1
9 root 20 0 0 0 0 S 0 0.0 0:01.10 events/0
10 root 20 0 0 0 0 S 0 0.0 0:00.37 events/1
11 root 20 0 0 0 0 S 0 0.0 0:00.00 cpuset
12 root 20 0 0 0 0 S 0 0.0 0:00.00 khelper
13 root 20 0 0 0 0 S 0 0.0 0:00.00 netns