View the number of concurrent connections in linux.

View the number of concurrent connections in linux.
1. view the number of concurrent requests and TCP connection status of the Web server (Nginx Apache:

Netstat-n | awk '/^ tcp/{++ S [$ NF]} END {for (a in S) print a, S [a]}'

Netstat-n | grep ^ tcp | awk '{print $ NF}' | sort-nr | uniq-c

Or:
Netstat-n | awk '/^ tcp/{++ state [$ NF]} END {for (key in state) print key, "t", state [key]}'
The returned results are generally as follows:

LAST_ACK 5 (number of requests awaiting processing)
SYN_RECV 30
ESTABLISHED 1597 (NORMAL Data Transmission status)
FIN_WAIT1 51
FIN_WAIT2 504
TIME_WAIT 1057 (processed, number of requests waiting for timeout)

Other parameters:

CLOSED: No connection is active or in progress
LISTEN: the server is waiting for incoming call
SYN_RECV: a connection request has arrived, waiting for confirmation
SYN_SENT: The application has started. Open a connection.
ESTABLISHED: normal data transmission status
FIN_WAIT1: The application says it has been completed
FIN_WAIT2: the other side has agreed to release
ITMED_WAIT: wait until all groups die
CLOSING: both sides attempt to close at the same time
TIME_WAIT: the other side has initialized a release.
LAST_ACK: waiting for all groups to die

2. view the number of processes running Nginx
Ps-ef | grep nginx | wc-l
The returned number is the number of processes running nginx.
Ps-ef | grep httpd | wc-l

3. view the number of Web server process connections:
Netstat-antp | grep 80 | grep ESTABLISHED-c