Linux commands--monitoring related

1.netstat

Used to display various network related information, such as network connection, routing table, interface status (Interface Statistics), masquerade connection, multicast member (multicast memberships) and so on.

Common parameters:

• -A (All) displays all options and does not show listen related by default
• -T (TCP) displays only TCP-related options
• -U (UDP) displays only UDP-related options
• -N refuses to display aliases, showing all numbers converted to numbers.
• -l list only service status in Listen (listening)
• -P Displays the program name that establishes the associated link
• -R display routing information, routing table
• -e display extended information, such as UID, etc.
• -S statistics according to each protocol
• -C executes the netstat command every other fixed time.

2.tcpdump

Packet analysis tools that intercept packets on the network based on the user's definition. Tcpdump can intercept the "head" of the packets that are transmitted in the network to provide analysis. It supports filtering on the network layer, protocol, host, network, or port, and provides logical statements such as and, or, not, to help you get rid of useless information.

3.ipcs

Write some information about the communication facilities between the active processes to the standard output.

Common parameters:

• -A is the default output information that prints out all the inter-process communication methods in the current system
• -m prints information about interprocess communication using shared memory
• -Q prints information about interprocess communication using Message Queuing
• -S print out information for interprocess communication using signals

4.ipcrm

Delete message queues, signal sets, or shared memory identities. This permission is available only to the Super administrator, or to the creator of the IPC object.

Common parameters:

• -M Shmkey removing shared memory segments created with Shmkey
• -M Shmid removing shared memory segments identified with Shmid
• -Q msgkey Remove Message Queuing created with Msqkey
• -Q msqid Remove Message Queuing identified with Msqid
• -s Semkey removal of signals created with Semkey
• -s semid removal of signals identified with Semid

5.uptime

The following information is displayed in turn: The current time, how long the system has been running, how many users are currently logged in, the average load of the system in the past 1 minutes, 5 minutes, and 15 minutes.

6.free

View the size of the memory space in the system.

7.top

The system performance can be viewed dynamically, and the CPU, memory usage resources and related process information are analyzed.

8.ps

The PS command is used to list those processes that are currently running on the system. The PS command lists the current snapshots of those processes, which are those that are executing the PS command at the moment, and if you want to display process information dynamically, you can use the top command.

Linux commands--monitoring related