Process is a program or command being executed, each entity is a process that runs, has its own address space, and take up some system resources.
ps to view the current status of system processes
ps: process status process status
1. The basic syntax
the AUX PS | grep xxx (functional description: View all processes)
-ef PS | grep xxx (Function Description : You can view the child parent relationship between processes)
2. Option Description
Table 1-35
| Options |
Features |
| -a |
Select all processes |
| -u |
Display all processes for all users |
| -x |
The process does not display terminal |
3. Function Description
( . 1 ) PS AUX displayed information
The USER : The process by which user generated
PID : Process ID number
CPU% : The process uses CPU percentage of resources, the higher the occupation, the more resource-intensive process;
MEM% : The percentage of physical memory occupied by the process, the higher the occupation, the more resource-intensive process;
VSZ : This process uses virtual memory size in KB ;
RSS : The process uses the size of the actual physical memory, the unit KB ;
TTY : The process which is running in the terminal. Which tty1-tty7 behalf of the local terminal console, tty1-tty6 is a local character interface terminal, tty7 is a graphics terminal. pts / 0-255 behalf of the virtual terminal.
STAT : process status. Common states are: R : run, S : sleeping, T : Stop state, S : contains sub-process, + : behind the scenes
The START : Start time of the process
The TIME : This process uses CPU computing time, the attention is not the system time
The COMMAND : command name for this process to produce
( 2 ) PS -ef display information described
UID : User ID
PID : Process ID
PPID : parent process ID
C : the CPU for calculating the execution priority factor. A higher value process is CPU intensive operations, will reduce the execution priority; Smaller values indicates that the process is I / O intensive operations, execution priority increases
STIME : process start time
TTY : Complete terminal name
The TIME : the CPU time
CMD : Command to start the process and parameters used
4. Experience Skills
If you want to see the process of CPU usage and memory usage , you can use the aux;
If you want to see the parent process ID can be used ef;
5. Case practical operation
[Root @ hadoop101 datas] # ps aux
FIG 1-161 shown
Figure 1-161 view the process of CPU usage and memory usage
[root@hadoop101 datas]# ps -ef
FIG 1-162 shown
Figure 1-162 parent process to see the process ID
kill terminate the process
1. The basic syntax
kill [options] process ID (Function Description: kill the process by process ID)
killall process name (Function Description: Kill processes by name , and also supports wildcards, which due to the load becomes too large to be useful when the system is very slow )
2. Option Description
Table 1-36
| Options |
Features |
| -9 |
Indicates force in the process stops immediately |
3. Case practical operation
( 1 ) kill the browser process
[root @ hadoop101 Desktop ] # kill -9 5102
( 2 ) by killing the process process name
[root @ hadoop101 Desktop ] # killall firefox
pstree view the process tree
1. The basic syntax
pstree [ Options ]
2. Option Description
Table 1-37
| Options |
Features |
| -p |
Display process PID |
| -u |
It belongs to a user display process |
3. Case practical operation
( 1 ) show the process pid
[root@hadoop101 datas]# pstree -p
( 2 ) show the process belongs to the user
[root@hadoop101 datas]# pstree -u
top view system health
1. Basic Commands
top [ options ]
2. Option Description
Table 1-38
| Options |
Features |
| -d number of seconds |
Specifies the top command updates every few seconds. The default is 3 seconds top command among interactive mode commands can be executed: |
| -i |
The top does not show any idle or zombie processes. |
| -p |
By specifying monitoring process ID to monitor only the status of a process. |
3. Instructions
Table 1-39
| operating |
Features |
| P |
To CPU usage sort, this is the default |
| M |
To sort of memory usage |
| N |
With PID sorting |
| q |
Exit top |
4. Interpretation of field results
The first line of information for the task queue information
Table 1-40
| content |
Explanation |
| 12:26:46 |
Current time |
| up 1 day, 13:32 |
Runtime system, the machine has been running . 1 days 13 is hours 32 minutes |
| 2 users |
Two users currently logged on |
| load average: 0.00, 0.00, 0.00 |
Before the system . 1 min . 5 minutes, 15 average load minutes. Less than generally believed . 1 , the load is small. If greater than 1 , the system load has been exceeded. |
The second line process information
Table 1-41
| Tasks: 95 total |
The total number of processes in the system |
| 1 running |
The number of running processes |
| 94 sleeping |
Sleep process |
| 0 stopped |
Stopping the process |
| 0 zombie |
Zombie process. If it is not 0 , you need to manually check the zombie process |
The third behavior CPU information
Table 1-42
| Cpu(s): 0.1%us |
User Mode occupied by the CPU percentage |
| 0.1% its |
System Mode occupied by the CPU percentage |
| 0.0% ni |
Changed the priority of the user processes CPU percentage |
| 99.7%id |
Idle CPU 's CPU percentage |
| 0.1% wa |
Waiting for input / occupation process output CPU percentage |
| 0.0%hi |
Hardware interrupt request service occupied CPU percentage |
| 0.1% and |
软中断请求服务占用的CPU百分比 |
| 0.0%st |
st（Steal time）虚拟时间百分比。就是当有虚拟机时，虚拟CPU等待实际CPU的时间百分比。 |
第四行为物理内存信息
表1-43
| Mem: 625344k total |
物理内存的总量，单位KB |
| 571504k used |
已经使用的物理内存数量 |
| 53840k free |
空闲的物理内存数量，我们使用的是虚拟机，总共只分配了628MB内存，所以只有53MB的空闲内存了 |
| 65800k buffers |
作为缓冲的内存数量 |
第五行为交换分区（swap）信息
表1-44
| Swap: 524280k total |
交换分区（虚拟内存）的总大小 |
| 0k used |
已经使用的交互分区的大小 |
| 524280k free |
空闲交换分区的大小 |
| 409280k cached |
作为缓存的交互分区的大小 |
5．案例实操
[root@hadoop101 atguigu]# top -d 1
[root@hadoop101 atguigu]# top -i
[root@hadoop101 atguigu]# top -p 2575
执行上述命令后，可以按P、M、N对查询出的进程结果进行排序。
netstat 显示网络统计信息和端口占用情况
1．基本语法
netstat -anp |grep 进程号 （功能描述：查看该进程网络信息）
netstat -nlp | grep 端口号 （功能描述：查看网络端口号占用情况）
2．选项说明
表1-45
| 选项 |
功能 |
| -n |
拒绝显示别名，能显示数字的全部转化成数字 |
| -l |
仅列出有在listen（监听）的服务状态 |
| -p |
表示显示哪个进程在调用 |
3．案例实操
（1）通过进程号查看该进程的网络信息
[root@hadoop101 hadoop-2.7.2]# netstat -anp | grep 火狐浏览器进程号
unix 2 [ ACC ] STREAM LISTENING 20670 3115/firefox /tmp/orbit-root/linc-c2b-0-5734667cbe29
unix 3 [ ] STREAM CONNECTED 20673 3115/firefox /tmp/orbit-root/linc-c2b-0-5734667cbe29
unix 3 [ ] STREAM CONNECTED 20668 3115/firefox
unix 3 [ ] STREAM CONNECTED 20666 3115/firefox
（2）查看某端口号是否被占用
[root@hadoop101 桌面]# netstat -nlp | grep 20670
unix 2 [ ACC ] STREAM LISTENING 20670 3115/firefox /tmp/orbit-root/linc-c2b-0-5734667cbe29