Reuse existing ssh-agent or start a new one

reuse_agent.sh

#!/usr/bin/env bash
# This is a fork created to be used with Git Bash that comes with the installation
# of Git for Windows (https://gitforwindows.org/), and it was tested only on that
# environment.
# Append this to your .bashrc to reuse an existing ssh-agent, or if you don't have
# a .bashrc file (normally located in Windows under 'C:\Users\username'), then
# make this your .bashrc file.

LOGNAME=username
GOT_AGENT=0

# List all the files that follow the SSH agent socket pattern, with the newest
# one at the top of the list. The top one is probably the one we want to use
for FILE in $(ls -t /tmp/ssh-*/agent.[0-9]* 2>/dev/null)
do
    # As the values in FILE are socket file names, the `ls` command adds a `=`
    # at the end of the string. Here we are removing that last character.
    SOCK_FILE=${FILE%?}

    # Now check if there are intances of the SSH agent running
    PIDLIST=($(ps -fu $LOGNAME | awk '/ssh-agent/ {print $2;}'))
    
    COUNT=${#PIDLIST[@]}
    if [ $COUNT -gt "1" ]
    then
        echo "Multiple ($COUNT) ssh-agents are running. The first available will be selected"
    fi

    for PID in "${PIDLIST[@]}"
    do
        # If PID was not set, get out of here to start a new ssh-agent
        if [ -z $PID ]
        then
            echo "No ssh-agent is running. Will start new agent..."
            break
        else
            SSH_AUTH_SOCK=${SOCK_FILE}; export SSH_AUTH_SOCK;
            SSH_AGENT_PID=${PID}; export SSH_AGENT_PID;

            ssh-add -l > /dev/null
            if [ $? != 2 ]
            then
                GOT_AGENT=1
                echo "Agent pid $PID"
                break
            fi
        fi
    done

    if [ $GOT_AGENT = 1 ]
    then
        break
    fi
    echo "Skipping file $FILE"
done

# If no ssh-agent was found, then start one and add a key. If your key is not in
# the default location, or if it doesn't use the default name ("~/.ssh/id_rsa" or
# in Windows "C:\Users\username\.ssh\id_rsa"), then add the correct path and key
# name to the `ssh-add` command. Like `ssh-add /c/your/key/path/my_id_rsa_key`
if [ $GOT_AGENT = 0 ]
then
    eval `ssh-agent`
    ssh-add
fi

setSSHforVS2017.sh

#!/usr/bin/env bash
# Set the already running ssh-agent so that the Windows environment recognises it, 
# i.e. Visual Studio 2017 recognises the ssh-agent.
# This will need to be run after an ssh-agent was already started and set, and before running
# Visual Studio 2017.
# I have set up my Git-Bash so that just starting it will start a new ssh-agent, or set one if
# one is already running.
# So first run Git-Bash, which will set the variables used below.
# Then run this script, and close Git-Bash.
# Finally start VS 2017.
# Source of this code:
# https://stackoverflow.com/questions/48885315/get-visual-studio-2017-to-work-with-ssh-agent-ssh-add-for-git/49071597

if [[ `uname` == MINGW* ]]
then
    setx SSH_AUTH_SOCK $SSH_AUTH_SOCK > /dev/null
    setx SSH_AGENT_PID $SSH_AGENT_PID > /dev/null
    echo "Done. Close Git-Bash for the change to take effect, and restart Visual Studio."
fi