I order to find and replace all string in text file use

sed -i 's/find_text/replace_text/' my_text_file.txt

When runned out of memory and redis fail
- try to stop everything with excessive usage of RAM
- fix redis db file with ./redis-check-aof --fix fdbfilename.aof

Get response time with curl:

Total time

curl -o /dev/null -s -w 'Total: %{time_total}s\n' https://www.google.com

Establish connection/time to first byte/total time

Controlling the Screen
The following shortcuts allow you to control what appears on the screen.

Check your IPv6 subnet with
subnetcalc ipv6_ip_address

Check indexes and its sizes

GET /_cat/indices

Check single index
GET /my_index_name/_stats

systemctl list-unit-files | grep enabled

For a dig with dns request flow response use

dig hostname.tld +trace

First part of ipsec site2site VPN

This setup is done on Mikrotik (or any similar router side)