Shell-script - Check the response of multiple server, Netcat - Test servers response time

Check the response of multiple server

Below is a simple script to test multiple servers responce. Here we are testing whether the port 22 is open or not.
for a in $(seq -f "mylin%04g" 411 1 414)
do
nc -zvw 2 $a 22
done
Output:
nc: connect to mylin0411 port 22 (tcp) timed out: Operation now in progress
nc: connect to mylin412 port 22 (tcp) timed out: Operation now in progress
nc: connect to mylin0413 port 22 (tcp) timed out: Operation now in progress
nc: connect to mylin0414 port 22 (tcp) timed out: Operation now in progress

Netcat command to test the port 22.
nc -zvw 2 mylin0411 22
Output:
nc: connect to el0411 port 22 (tcp) timed out: Operation now in progress

nc -zvw 2 mylin0411 22
Output:
nc: timeout cannot be negative

nc -zvw 2 ourlinux 22

OUTPUT:
Connection to ourlinux 22 port [tcp/ssh] succeeded!

where,

z - Specifies that nc should just scan for listening daemons, without sending any data to them. It is an error to use this option in conjunction with the -l option.

v - Have nc give more verbose output.

w : timeout - If a connection and stdin are idle for more than timeout seconds, then the connection is silently closed. The -w flag has no effect on the -l option, i.e. nc will listen forever for a connection, with or without the -w flag. The default is no timeout.

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