could not open a connection to your authentication agent. ssh-add ubuntu code example

Example 1: ssh-add could not open a connection to your authentication agent centos

##1
$ cd ~/.ssh
##2
#ubuntu
$ eval $(ssh-agent)
#CentOS
$ exec ssh-agent bash
##3
$ ssh-add my_id_rsa

Example 2: ssh-add could not open a connection to your authentication agent

eval `ssh-agent -s`
ssh-add

Example 3: ssh-add could not open a connection to your authentication agent

# wsl2 solution with vscode to connect to Github repository (not sure why it works with the agent but not otherwise keys are in Ubuntu ie. could be with it being in a VM)
eval $(ssh-agent)
ssh-add