You might have tried adding a key with:

ssh-add .ssh/id_rsa

only to get this error:

ssh-add .ssh/id_rsa
Could not open a connection to your authentication agent.[/code]
If this happens, it is because your ssh agent is not running in the terminal.

Run this:
exec ssh-agent bash
which will cause it to resource your .bashrc files and start the agent.
Now try readding the key again:
ssh-add .ssh/id_rsa
Identity added: .ssh/id_rsa (.ssh/id_rsa)
 
Joel G Mathew
Joel G Mathew, known in tech circles by the pseudonym Droidzone, is an opensource and programming enthusiast.
He is a full stack developer, whose favorite languages are currently Python and Vue.js. He is also fluent in Javascript, Flutter/Dart, Perl, PHP, SQL, C and bash shell scripting. He loves Linux, and can often be found tinkering with linux kernel code, and source code for GNU applications. He used to be an active developer on XDA forums, and his tinkered ROMS used to be very popular in the early 2000s.
His favorite pastime is grappling with GNU compilers, discovering newer Linux secrets, writing scripts, hacking roms, and programs (nothing illegal), reading, blogging. and testing out the latest gadgets.
When away from the tech world, Dr Joel G. Mathew is a practising ENT Surgeon, busy with surgeries and clinical practise.