1. Process management tool
In this section we introduce process management tools;
Using the process management tool, we can query the current running status of the program, or terminate a process;
Any process is associated with a file; we will use the lsof tool (list opened files) to list the files that have been opened in the system. In the Linux environment, everything is a file, devices are files, directories are files, and even sockets are files. Using the lsof command well is very helpful for daily Linux management.
1.1. Query process
Query running process information
$ps -ef
eg: Query processes belonging to user colin115
$ps -ef | grep colin115
$ps -lu colin115
Query process ID (suitable for only remembering some process fields)
$pgrep 查找进程
eg:查询进程名中含有re的进程
[/home/weber#]pgrep -l re
2 kthreadd
28 ecryptfs-kthrea
29515 redis-server
Show all processes in full format
$ps -ajx
Display process information and update in real time
$top
View the process status occupied by the port:
lsof -i:3306
View the files opened by the process of user username
$lsof -u username
Query the files currently opened by the init process
$lsof -c init
Query the files opened by the specified process ID (23295):
$lsof -p 23295
Query the files opened by the process in the specified directory (use +D to recurse the directory):
$lsof +d mydir1/
1.2. Terminate the process
Kill the process with the specified PID (PID is Process ID)
$kill PID
kill related process
kill -9 3434
Kill the job (job is the job number)
$kill %job
1.3. Process monitoring
View the processes that use the most CPU and memory in the system;
$top
(->)P
Enter the top command to enter the interactive interface; then enter the character command to display the corresponding process status:
For processes, what we usually want to know most is which processes occupy the most CPU and occupy the most memory. The following two commands will suffice:
P：根据CPU使用百分比大小进行排序。
M：根据驻留内存大小进行排序。
i：使top不显示任何闲置或者僵死进程。
Here are the most used options. For more detailed usage, see the task manager under top linux
1.4. Analyzing the thread stack
Use the command pmap to output the status of the process memory, which can be used to analyze the thread stack;
$pmap PID
eg:
[/home/weber#]ps -fe| grep redis
weber 13508 13070 0 08:14 pts/0 00:00:00 grep --color=auto redis
weber 29515 1 0 2013 ? 02:55:59 ./redis-server redis.conf
[/home/weber#]pmap 29515
29515: ./redis-server redis.conf
08048000 768K r-x-- /home/weber/soft/redis-2.6.16/src/redis-server
08108000 4K r---- /home/weber/soft/redis-2.6.16/src/redis-server
08109000 12K rw--- /home/weber/soft/redis-2.6.16/src/redis-server
1.5. Comprehensive application
Terminate all processes whose process names start with av_ under user colin115:
ps -u colin115 | awk '/av_/ {print "kill -9 " $1}' | sh
Terminate all processes whose process name contains HOST under user colin115:
ps -fe| grep colin115|grep HOST |awk '{print $2}' | xargs kill -9;
2. Performance monitoring
In the process of using the operating system, we often need to check the current performance, and need to know the usage of CPU, memory and hard disk; the tools introduced in this section can meet the daily work requirements;
2.1. Monitor CPU
View CPU usage
$sar -u
eg:
$sar -u 1 2
[/home/weber#]sar -u 1 2
Linux 2.6.35-22-generic-pae (MyVPS) 06/28/2014 _i686_ (1 CPU)
09:03:59 AM CPU %user %nice %system %iowait %steal %idle
09:04:00 AM all 0.00 0.00 0.50 0.00 0.00 99.50
09:04:01 AM all 0.00 0.00 0.00 0.00 0.00 100.00
The latter two parameters indicate the frequency of monitoring, such as 1 and 2 in the example, which means sampling once per second, and a total of 2 samples;
View CPU load average
$sar -q 1 2
After sar specifies -q, you can view the number of processes in the running queue, process size on the system, average load, etc.;
2.2. Query memory
Check the memory usage status After specifying -r in sar, you can check the memory usage status;
$sar -r 1 2
09:08:48 AM kbmemfree kbmemused %memused kbbuffers kbcached kbcommit %commit kbactive kbinact
09:08:49 AM 17888 359784 95.26 37796 73272 507004 65.42 137400 150764
09:08:50 AM 17888 359784 95.26 37796 73272 507004 65.42 137400 150764
Average: 17888 359784 95.26 37796 73272 507004 65.42 137400 150764
View memory usage
$free -m
2.3. Query page exchange
Check the status of page swapping. When the page is swapping, the throughput of the server will drop significantly. When the server is in poor condition, if you suspect that page swapping occurs due to insufficient memory, you can use the sar -W command to confirm whether a large amount of traffic has occurred. exchange;
$sar -W 1 3
2.4. Query hard disk usage
View disk space usage
$df -h
Query the space usage in the current directory
du -sh -h是人性化显示 s是递归整个目录的大小
View the sorted sizes of all folders in this directory
for i in `ls`; do du -sh $i; done | sort
或者
du -sh `ls`
2.5. Comprehensive application
When sar is not available in the system, the following tools can be used instead: vmstat under linux, prstat under Unix system
eg: View cpu, memory, and usage: vmstat nm (n is the monitoring frequency, m is the number of monitoring times)
[/home/weber#]vmstat 1 3
procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu----
r b swpd free buff cache si so bi bo in cs us sy id wa
0 0 86560 42300 9752 63556 0 1 1 1 0 0 0 0 99 0
1 0 86560 39936 9764 63544 0 0 0 52 66 95 5 0 95 0
0 0 86560 42168 9772 63556 0 0 0 20 127 231 13 2 84 0
Use the watch tool to monitor changes When it is necessary to continuously monitor a certain data change of the application, the watch tool can meet the requirements; after executing the watch command, it will enter an interface and output the currently monitored data. Once the data changes, it will be highlighted display changes;
eg: When operating redis, monitor memory changes:
$watch -d -n 1 './redis-cli info | grep memory'
(以下为watch工具中的界面内容，一旦内存变化，即实时高亮显示变化）
Every 1.0s: ./redis-cli info | grep memory
used_memory:45157376
used_memory_human:43.07M
used_memory_rss:47628288
used_memory_peak:49686080
used_memory_peak_human:47.38M