linux - How to check if ssh-agent is already running in bash?

Question

I have a sample sh script on my Linux environment, which basically run's the ssh-agent for the current shell, adds a key to it and runs two git commands:

#!/bin/bash
eval "$(ssh-agent -s)"
ssh-add /home/duvdevan/.ssh/id_rsa

git -C /var/www/duvdevan/ reset --hard origin/master
git -C /var/www/duvdevan/ pull origin master

Script actually works fine, but every time I run it I get a new process so I think it might become a performance issue and I might end up having useless processes out there.

An example of the output:

Agent pid 12109
Identity added: /home/duvdevan/.ssh/custom_rsa (rsa w/o comment)

Also, along with all this, is it possible to find an existing ssh-agent process and add my keys into it?

Answer 1

No, really, how to check if ssh-agent is already running in bash?

Answers so far don't appear to answer the original question...

Here's what works for me:

if ps -p $SSH_AGENT_PID > /dev/null
then
   echo "ssh-agent is already running"
   # Do something knowing the pid exists, i.e. the process with $PID is running
else
eval `ssh-agent -s`
fi

This was taken from here