Server monitoring

1. watch -n 2 -d free -m

2. free -m

3. netstat -n | grep tcp | awk '{print $5}'|grep -v '127.0.0.1' | wc -l

4. top

one. TOP Top Five Lines of Statistics The top five lines of the

statistics area are the overall system statistics.

1. The first line is the task queue information, which is

the same as the execution result of the uptime command:

[root@localhost ~]# uptime

13:22:30 up 8 min, 4 users, load average: 0.14, 0.38, 0.25

The content is as follows:

12: 38:33


current time

up 50days


system running time, the format is hour: minute

1 user


number of currently logged in users

load average: 0.06, 0.60, 0.48


system load, that is, the average length of the task queue. The three values ​​are the average values ​​from 1 minute, 5 minutes, and 15 minutes ago to the present.

2. The second and third lines are information about the process and CPU.

When there are multiple CPUs, these contents may exceed two lines. The content is as follows:

Tasks: 29 total total number of


processes

1 running number of running


processes

28 The number of sleeping processes


0

stopped The number of stopped


processes

0 zombies The number of zombie


processes Process occupied CPU percentage 98.7% id idle CPU percentage 0.0% wa CPU time percentage waiting for input and output 0.0% hi 0.0% si 3. The fourth and fifth rows are memory information. The content is as follows: Mem: 191272k total total physical memory 173656k used total physical memory used 17616k free memory total 22052k buffers used as kernel cache memory Swap: 192772k total total swap area 0k used total used swap area 192772k free total free swap area







































































123988k cached


buffered total swap area. The contents of the memory are swapped out to the swap area, and then swapped into the memory, but the used swap area has not been overwritten, and this value is the size of the swap area where these contents already exist in the memory. When the corresponding memory is swapped out again, there is no need to write to the swap area.

2. Process information

Column name


Meaning

PID


process id

PPID


parent process id

RUSER


Real user name

UID


process owner user id

USER


process owner user name

GROUP


process owner group name

TTY


Terminal name of the start process. Processes not started from the terminal are displayed as ?

PR


priority

NI


nice value. Negative values ​​indicate high priority, positive values ​​indicate the last CPU used by low priority

P


, which is only meaningful in a multi-CPU environment

%CPU


The percentage of CPU time used by the last update to the present

TIME


The total CPU time used by the process, in seconds

TIME+


The total CPU time used by the process, in units of 1/100 seconds

%MEM


The percentage of physical memory used by the process




The total amount of virtual memory used by the VIRT process, in kb. VIRT=SWAP+RES The size of the virtual memory used by the

SWAP


process to be swapped out, in kb. The size of the physical memory used by the

RES process but not swapped out, in kb.


RES=CODE+DATA The physical memory size occupied by the

CODE


executable code, in kb The physical memory size occupied by the part (data segment + stack) other than the

DATA executable code, in kb SHR shared memory size, in kb nFLT Page fault times nDRT The number of pages modified since the last write. S process state.             D=Uninterruptible sleep state             R=Run             S=Sleep             T=Track/Stop             Z=Zombie process COMMAND command name/command line WCHAN If the process is sleeping, it will display the sleeping system function name Flags task flag, refer to sched. h