1 , by ps two forms of the Options command to view process information
[root@localhost ~]# ps aux
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
root 1 0.0 0.3 128296 6836 ? Ss 09:21 0:02 /usr/lib/sys
root 2 0.0 0.0 0 0 ? S 09:21 0:00 [kthreadd]
[root@localhost ~]# ps elf
F UID PID PPID PRI NI VSZ RSS WCHAN STAT TTY TIME COMMAND
4 0 3707 3695 20 0 116620 3216 do_wai Ss pts/1 0:00 -bash U
4 0 3755 3707 20 0 153232 1780 - R + pts / 1 0:00 \ _ ps
4 0 3639 3627 20 0 116740 3284 n_tty_ Ss+ pts/0 0:00 bash US
4 0 1450 1310 20 0 309184 38588 ep_pol Ssl+ tty1 0:01 /usr/b
2 , the top viewing process command
3 , by pgrep view the command sshd service of process ID
4 , view the system process tree
5 , so dd if = / dev / zero of = / root / file bs = 1M count = 8190 command operations in the foreground
6 , the first 5 issues the command operations transferred to the background and pauses
7 , so dd IF = / dev / ZERO of = / the root / file2 COUNT = 102 BS = 1M *. 4 command operations run in the background
8 , see the background of the task list
9 , recovery dd if = / dev / zero of = / root / file bs = 1M count = 8190 allowed to continue in the background
10, query dd if = / dev / zero of = / root / file bs = 1M count = 8190 processes the command and through the kill kill
11 , plans to set up a one-time task in 18 : 00 shut down the system, and view task information
12 , in order to root set periodic scheduled tasks status
a) 每天晚上的24点时打包压缩 /etc/passwd /etc/shadow /etc/group /etc/gshadow 为 file.tar.gz
b) 每周一的每隔五分钟列出磁盘使用状况
c) 每天的8:30与互联网时间同步服务器pool.ntp.org同步时间
13、通过crontab命令查看root的计划任务，通过文件查看类工具列出/var/spool/cron下对应的文件内容
