Can I specify multiple users for myself in .gitconfig?

In my ~/.gitconfig, I list my personal email address under [user], since that's what I want to use for Github repos.

But, I've recently started using git for work, too. My company's git repo allows me to commit, but when it sends out announcements of new changesets, it says they are from Anonymous because it doesn't recognize the email address in my .gitconfig - at least, that's my theory.

Is it possible to specify multiple [user] definitions in .gitconfig? Or is there some other way to override the default .gitconfig for a certain directory? In my case, I check out all work code in ~/worksrc/ - is there a way to specify a .gitconfig for only that directory (and its subdirectories)?

You can configure an individual repo to use a specific user / email address which overrides the global configuration. From the root of the repo, run

git config user.name "Your Name Here"
git config user.email [email protected]

whereas the default user / email is configured in your ~/.gitconfig

git config --global user.name "Your Name Here"
git config --global user.email [email protected]

Since git 2.13, it is possible to solve this using newly introduced Conditional includes.

An example:

Global config ~/.gitconfig

[user]
    name = John Doe
    email = [email protected]

[includeIf "gitdir:~/work/"]
    path = ~/work/.gitconfig

Work specific config ~/work/.gitconfig

[user]
    email = [email protected]

---

Remember that [includeIf...] should follows default [user] at the top.

Or you can add following information in your local .git/config file

[user] 	
 	name = Your Name
 	email = [email protected]

One command github accounts switch

This solution takes the form of a single git alias. Once executed, the current project user will be attached to another account

Generate ssh keys

ssh-keygen -t rsa -C "[email protected]" -f '/Users/arnaudrinquin/.ssh/id_rsa'

[...]

ssh-keygen -t rsa -C "[email protected]" -f '/Users/arnaudrinquin/.ssh/id_rsa_pro'

Link them to your GitHub / Bitbucket accounts

1. copy default public key pbcopy < ~/.ssh/id_rsa.pub
2. login to your GitHub acount
3. paste the key in the add SSH key github page
4. copy other public key pbcopy < ~/.ssh/id_rsa_pro.pub
5. repeat and adapt steps 2 to 4 for every other account

Step 1. Automatic ssh key switching.

We can configure ssh to send a use a specific encryption key depending on the host. The nice thing is that you can have several aliases for the same hostname.

See this example ~/.ssh/config file:

# Default GitHub
Host github.com
  HostName github.com
  User git
  IdentityFile ~/.ssh/id_rsa

# Professional github alias
Host github_pro
  HostName github.com
  User git
  IdentityFile ~/.ssh/id_rsa_pro

git remote configuration

You can now use these aliases in the git remotes by changing [email protected] by git@github_pro.

You can either change your existing projects remotes (using something like git remote set-url origin git@github_pro:foo/bar.git) or adapt them directly when cloning them.

git clone [email protected]:ArnaudRinquin/atom-zentabs.git

using alias, it become:

git clone git@github_pro:ArnaudRinquin/atom-zentabs.git

Step 2. Changing git user.email

Git config settings can be global or per project. In our case, we want a per project settings. It is very easy to change it:

git config user.email '[email protected]'

While this is easy, it takes way to long for the developers we are. We can write a very simple git alias for that.

We are going to add it to the ~/.gitconfig file.

[user]
	name = Arnaud Rinquin
	email = [email protected]

...

[alias]
	setpromail = "config user.email '[email protected]'"

Then, all we have to do is git setpromail to have our email changed for this project only.

Step 3. One command switch please?!

Wouldn’t it be nice to switch from default account to a specified one with a single parameter-less command? This is definitely possible. This command will have two steps:

• change current project remotes to the chosen aliases
• change current project user.email config

We already have a one command solution for the second step, but the first one is way harder. One command remote host change

Here comes the solution in the form of another git alias command to add to your ~/.gitconfig:

[alias]
  changeremotehost = !sh -c \"git remote -v | grep '$1.*fetch' | sed s/..fetch.// | sed s/$1/$2/ | xargs git remote set-url\"

This allows changing all remotes from one host to another (the alias). See the example:

$ > git remote -v
origin	git@github.com:ArnaudRinquin/arnaudrinquin.github.io.git (fetch)
origin	git@github.com:ArnaudRinquin/arnaudrinquin.github.io.git (push)

$ > git changeremotehost github.com github_pro

$ > git remote -v
origin	git@github_pro:ArnaudRinquin/arnaudrinquin.github.io.git (fetch)
origin	git@github_pro:ArnaudRinquin/arnaudrinquin.github.io.git (push)

Combine them all

We now just have to combine the two commands into one, this is quite easy. See how I also integrate bitbucket host switching.

[alias]
  changeremotehost = !sh -c \"git remote -v | grep '$1.*fetch' | sed s/..fetch.// | sed s/$1/$2/ | xargs git remote set-url\"
  setpromail = "config user.email '[email protected]'"
  gopro = !sh -c \"git changeremotehost github.com github_pro && git changeremotehost bitbucket.com bitbucket_pro && git setpromail\"

Source Link -Github

Source Link -Tutorial

After getting some inspiration from Orr Sella's blog post I wrote a pre-commit hook (resides in ~/.git/templates/hooks) which would set specific usernames and e-mail addresses based on the information inside a local repositorie's ./.git/config:

You have to place the path to the template directory into your ~/.gitconfig:

[init]
    templatedir = ~/.git/templates

Then each git init or git clone will pick up that hook and will apply the user data during the next git commit. If you want to apply the hook to already exisiting repos then just run a git init inside the repo in order to reinitialize it.

Here is the hook I came up with (it still needs some polishing - suggestions are welcome). Save it either as

~/.git/templates/hooks/pre_commit

or

~/.git/templates/hooks/post-checkout

and make sure it is executable: chmod +x ./post-checkout || chmod +x ./pre_commit

#!/usr/bin/env bash

# -------- USER CONFIG
# Patterns to match a repo's "remote.origin.url" - beginning portion of the hostname
git_remotes[0]="Github"
git_remotes[1]="Gitlab"

# Adjust names and e-mail addresses
local_id_0[0]="my_name_0"
local_id_0[1]="my_email_0"

local_id_1[0]="my_name_1"
local_id_1[1]="my_email_1"

local_fallback_id[0]="${local_id_0[0]}"
local_fallback_id[1]="${local_id_0[1]}"


# -------- FUNCTIONS
setIdentity()
{
    local current_id local_id

    current_id[0]="$(git config --get --local user.name)"
    current_id[1]="$(git config --get --local user.email)"

    local_id=("$@")

    if [[ "${current_id[0]}" == "${local_id[0]}" &&
          "${current_id[1]}" == "${local_id[1]}" ]]; then
        printf " Local identity is:\n"
        printf "»  User: %s\n»  Mail: %s\n\n" "${current_id[@]}"
    else
        printf "»  User: %s\n»  Mail: %s\n\n" "${local_id[@]}"
        git config --local user.name "${local_id[0]}"
        git config --local user.email "${local_id[1]}"
    fi

    return 0
}

# -------- IMPLEMENTATION
current_remote_url="$(git config --get --local remote.origin.url)"

if [[ "$current_remote_url" ]]; then

    for service in "${git_remotes[@]}"; do

        # Disable case sensitivity for regex matching
        shopt -s nocasematch

        if [[ "$current_remote_url" =~ $service ]]; then
            case "$service" in

                "${git_remotes[0]}" )
                    printf "\n»» An Intermission\n»  %s repository found." "${git_remotes[0]}"
                    setIdentity "${local_id_0[@]}"
                    exit 0
                    ;;

                "${git_remotes[1]}" )
                    printf "\n»» An Intermission\n»  %s repository found." "${git_remotes[1]}"
                    setIdentity "${local_id_1[@]}"
                    exit 0
                    ;;

                * )
                    printf "\n»  pre-commit hook: unknown error\n» Quitting.\n"
                    exit 1
                    ;;

            esac
        fi
    done
else
    printf "\n»» An Intermission\n»  No remote repository set. Using local fallback identity:\n"
    printf "»  User: %s\n»  Mail: %s\n\n" "${local_fallback_id[@]}"

    # Get the user's attention for a second
    sleep 1

    git config --local user.name "${local_fallback_id[0]}"
    git config --local user.email "${local_fallback_id[1]}"
fi

exit 0

---

EDIT:

So I rewrote the hook as a hook and command in Python. Additionally it's possible to call the script as a Git command (git passport), too. Also it's possible to define an arbitrary number of IDs inside a configfile (~/.gitpassport) which are selectable on a prompt. You can find the project at github.com: git-passport - A Git command and hook written in Python to manage multiple Git accounts / user identities.

With conditional includes in Git 2.13, it is now possible to have multiple user/email coexist on one machine with little work.

user.gitconfig has my personal name and email. work-user.gitconfig has my work name and email. Both files are at ~ path.

So my personal name/email applies by default. For c:/work/ dir, my work name/email is applied. For c:/work/github/ dir, my personal name/email is applied. This works as the last setting gets applied.

# ~/.gitconfig
[include]
	path = user.gitconfig
[includeIf "gitdir/i:c:/work/"]
	path = work-user.gitconfig
[includeIf "gitdir/i:c:/work/github/"]
	path = user.gitconfig

gitdir is case-sensitive and gitdir/i is case-insensitive.

"gitdir/i:github/" would apply the conditional include for any directory with github in its path.

If you do not want to have a default email address (email address links to a github user), you can configure that you want to be asked. How you can do that depends on the version of git you use, see below.

The (intended) drawback is that you have to configure your email address (and your name) once for every repository. So, you cannot forget to do it.

Version < 2.7.0

[user]
    name = Your name
    email = "(none)"

in your global configuration ~/.gitconfig as stated in a comment by Dan Aloni in Orr Sella's blog post. When trying to do the first commit in a repository, git fails with the nice message:

*** Please tell me who you are.

Run

  git config --global user.email "[email protected]"
  git config --global user.name "Your Name"

to set your account's default identity.
Omit --global to set the identity only in this repository.

fatal: unable to auto-detect email address (got '(none)')

The name is taken from the global config when the email address is set locally (the message is not perfectly accurate).

2.7.0 ≤ Version < 2.8.0

The behaviour in versions < 2.7.0 was not intended and fixed with 2.7.0. You can still use a pre-commit hook as described in Orr Sella's blog post. This solution works also for other versions, but the other solutions not for this version.

Version ≥ 2.8.0

Dan Aloni added an option to achieve that behaviour (see release notes). Use it with:

[user]
    useConfigOnly = true

To make it work you may not give a name or email address in the global config. Then, at the first commit, you get an error message

fatal: user.useConfigOnly set but no name given

So the message is not very instructive, but since you set the option explicitly, you should know what to do. In contrast to the solution of versions < 2.7.0, you always have to set both name and email manually.

Another option to get git to work with multiple names / emails is by aliasing git and using the -c flag to override the global and repository-specific config.

For example, by defining an alias:

alias git='/usr/bin/git -c user.name="Your name" -c user.email="[email protected]"'

To see whether it works, simply type git config user.email:

$ git config user.email
name@example.com

Instead of an alias, you could also put a custom git executable within your $PATH.

#!/bin/sh
/usr/bin/git -c user.name="Your name" -c user.email="[email protected]" "$@"

An advantage of these method over a repository-specific .git/config is that it applies to every git repository when the custom git program is active. In this way, you can easily switch between users/names without modifying any (shared) configuration.

Here are the complete steps after reading many answers here

How to set up Multiple SSH Keys settings for different github account

You might want to start checking your currently saved keys

$ ssh-add -l

If you decide to delete all cached keys before (optional, carefull about this)

$ ssh-add -D

Then you can create a ssh pub/priv key linked to each email/account that you wish/need to use

$ cd ~/.ssh
$ ssh-keygen -t rsa -C "[email protected]" <-- save it as "id_rsa_work"
$ ssh-keygen -t rsa -C "[email protected]" <-- save it as "id_rsa_pers"

After performing this commands you will have the following files created

~/.ssh/id_rsa_work		
~/.ssh/id_rsa_work.pub

~/.ssh/id_rsa_pers
~/.ssh/id_rsa_pers.pub 

Make sure authentication agent is running

$ eval `ssh-agent -s`

Add the generated keys as following (from the ~/.ssh folder)

$ ssh-add id_rsa_work
$ ssh-add id_rsa_pers

Now you can check your saved keys again

$ ssh-add -l

Now you need to add the generated public keys to your github/bickbuket server Acces Keys

Clone each of the repos to different folders

Go to the folder where the user work will work and execute this

$ git config user.name "Working Hard"
$ git config user.email "[email protected]" 

Just to see what this does check the contents of the ".git/config"

Go to the folder where the user pers will work and execute this

$ git config user.name "Personal Account"
$ git config user.email "[email protected]" 

Just to see what this does check the contents of the ".git/config"

After all this you will be able to commit your personal and work code by just switching between those two folders

In case you are using Git Bash and need to generate ssh keys under Windows follow this steps:

https://support.automaticsync.com/hc/en-us/articles/202357115-Generating-an-SSH-Key-on-Windows

git aliases (and sections in git configs) to the rescue!

add an alias (from command line):

git config --global alias.identity '! git config user.name "$(git config user.$1.name)"; git config user.email "$(git config user.$1.email)"; :'

then, set, for example

git config --global user.github.name "your github username"
git config --global user.github.email [email protected]

and in a new or cloned repo you can run this command:

git identity github

This solution isn't automatic, but unsetting user and email in your global ~/.gitconfig and setting user.useConfigOnly to true would force git to remind you to set them manually in each new or cloned repo.

git config --global --unset user.name
git config --global --unset user.email
git config --global user.useConfigOnly true

This answer is partially inspired by the post by @Saucier, but I was looking for an automated way to set user.name and user.email on a per repo basis, based on the remote, that was a little more light weight than the git-passport package that he developed. Also h/t to @John for the useConfigOnly setting. Here is my solution:

.gitconfig changes:

[github]
    name = <github username>
    email = <github email>
[gitlab]
    name = <gitlab username>
    email = <gitlab email>
[init]
    templatedir = ~/.git-templates
[user]
    useConfigOnly = true

post-checkout hook which should be saved to the following path: ~/.git-templates/hooks/post-checkout:

#!/usr/bin/env bash

# make regex matching below case insensitive
shopt -s nocasematch

# values in the services array should have a corresponding section in
# .gitconfig where the 'name' and 'email' for that service are specified
remote_url="$( git config --get --local remote.origin.url )"
services=(
    'github'
    'gitlab'
)

set_local_user_config() {
    local service="${1}"
    local config="${2}"
    local service_config="$( git config --get ${service}.${config} )"
    local local_config="$( git config --get --local user.${config} )"

    if [[ "${local_config}" != "${service_config}" ]]; then
        git config --local "user.${config}" "${service_config}"
        echo "repo 'user.${config}' has been set to '${service_config}'"
    fi
}

# if remote_url doesn't contain the any of the values in the services
# array the user name and email will remain unset and the
# user.useConfigOnly = true setting in .gitconfig will prompt for those
# credentials and prevent commits until they are defined
for s in "${services[@]}"; do
    if [[ "${remote_url}" =~ "${s}" ]]; then
        set_local_user_config "${s}" 'name'
        set_local_user_config "${s}" 'email'
        break
    fi
done

I use different credentials for github and gitlab, but those references in the code above could be replaced or augmented with any service that you use. In order to have the post-checkout hook automatically set the user name and email locally for a repo after a checkout make sure the service name appears in the remote url, add it to the services array in the post-checkout script and create a section for it in your .gitconfig that contains your user name and email for that service.

If none of the service names appear in the remote url or the repo doesn't have a remote the user name and email will not be set locally. In these cases the user.useConfigOnly setting will be in play which will not allow you to make commits until the user name and email are set at the repo level, and will prompt the user to configure that information.

After reading all the answers, that's the solution I came with:

Scenario:

• Local OS: Linux (bash)
• two accounts on GitHub (work/personal)
• ssh access with different keys
• my work account will be the "main" one (so it doesn't need custom configuration)

Configuration:

1. Set a "fake" host, which allows me to select the proper SSH keypair.
   At ~/.ssh/config:

   # Personal GitHub account
   Host github-personal
     HostName github.com
     User git
     IdentityFile ~/.ssh/id_rsa_personal
     IdentitiesOnly yes
   

2. "Tell" git it should use a custom configuration within a given directory subtree:
   At ~/.gitconfig:

   # My personal projects
   [includeIf "gitdir/i:~/REPOS/PERSONAL/"]
      path = ~/REPOS/PERSONAL/personal.gitconfig
   
   

3. Finally, my config at ~/REPOS/PERSONAL/personal.gitconfig:

   # gitconfig for personal projects
   [user]
     email = [email protected]
   
   [url "git@github-personal"]
     insteadOf = [email protected]
   

Once the three above are in place, I can clone a personal repo like this:

user@host:~/REPOS/PERSONAL$ git clone git@github.com:jmnavarrol/python-multigit.git
Cloning in 'python-multigit'...
(...)
user@host:~/REPOS/PERSONAL$ cd python-multigit && git remote -v
origin  git@github-personal:jmnavarrol/python-multigit.git (fetch)
origin  git@github-personal:jmnavarrol/python-multigit.git (push)
user@host:~/REPOS/PERSONAL/python-multigit$

The addition of the url rewriting at ~/REPOS/PERSONAL/personal.gitconfig...

[url "git@github-personal"]
  insteadOf = git@github.com

...is what allows me referencing the repo just by its "standard" URL in scripts, subrepos (i.e. the case of python-multigit itself -yes, lame attempt at a bit of self-promotion) without risking using the "wrong" URLs, therefore, the wrong authentication.

My two cents.

There is a simple solution that seems to work well for avoiding mistakes.

Simply remove the [user] section from your ~/.gitconfig, which will prevent you from making any commits without setting user.name for each repository.

In your ~/.bashrc, add some simple aliases for the user and email:

alias ggmail='git config user.name "My Name";git config user.email [email protected]'
alias gwork='git config user.name "My Name";git config user.email [email protected]'

Windows Environment

Additional this can be modified from Git Extensions --> Settings --> Global Settings, if you have it installed in your systems.

gitextensions-latest-release

Right Click on a folder/directory in Windows Environment to access these settings.

Update : How to switch/maintain multiple settings in Version 2.49

GIT_AUTHOR_EMAIL + local .bashrc

.bashrc_local: don't track this file, put it only on your work computer:

export GIT_AUTHOR_EMAIL='[email protected]'
export GIT_COMMITTER_EMAIL="$GIT_AUTHOR_EMAIL"

.bashrc: track this file, make it the same on both work and home computers:

F="$HOME/.bashrc_local"
if [ -r "$F" ]; then
    . "$F"
fi

I'm using https://github.com/technicalpickles/homesick to sync my dotfiles.

If only gitconfig would accept environment variables: https://stackoverflow.com/questions/11262010/shell-variable-expansion-in-git-config

Maybe it is a simple hack, but it is useful. Just generate 2 ssh keys like below.

Generating public/private rsa key pair.
Enter file in which to save the key (/Users/GowthamSai/.ssh/id_rsa): work
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in damsn.
Your public key has been saved in damsn.pub.
The key fingerprint is:
SHA256:CrsKDJWVVek5GTCqmq8/8RnwvAo1G6UOmQFbzddcoAY [email protected]
The key's randomart image is:
+---[RSA 4096]----+
|. .oEo+=o+.      |
|.o o+o.o=        |
|o o o.o. +       |
| =.+ .  =        |
|= *+.   S.       |
|o*.++o .         |
|=.oo.+.          |
| +. +.           |
|.o=+.            |
+----[SHA256]-----+

Same way create one more for personal. So, you have 2 ssh keys, work and company. Copy work.pub, work, personal.pub, personal to ~/.ssh/ Directory.

Then create a shell script with the following lines and name it as crev.sh (Company Reverse) with the following content.

cp ~/.ssh/work ~/.ssh/id_rsa
cp ~/.ssh/work.pub ~/.ssh/id_rsa.pub

Same way, create one more called prev.sh (Personal Reverse) with the following content.

cp ~/.ssh/personal ~/.ssh/id_rsa
cp ~/.ssh/personal.pub ~/.ssh/id_rsa.pub

in ~/.bashrc add aliases for those scripts like below

alias crev="sh ~/.ssh/crev.sh"
alias prev="sh ~/.ssh/prev.sh"
source ~/.bashrc

Whenever you wanna use company, just do crev, and if you wanna use personal do prev :-p.

Add those ssh keys to your GitHub accounts. Make sure, you don't have id_rsa generated previously, because those scripts will overwrite id_rsa. If you have already generated id_rsa, use that for one of the accounts. Copy them as personal and skip the generation of personal keys.

I made a bash function that handle that. Here is the Github repo.

For record:

# Look for closest .gitconfig file in parent directories
# This file will be used as main .gitconfig file.
function __recursive_gitconfig_git {
    gitconfig_file=$(__recursive_gitconfig_closest)
    if [ "$gitconfig_file" != '' ]; then
        home="$(dirname $gitconfig_file)/"
        HOME=$home /usr/bin/git "$@"
    else
        /usr/bin/git "$@"
    fi
}

# Look for closest .gitconfig file in parents directories
function __recursive_gitconfig_closest {
    slashes=${PWD//[^\/]/}
    directory="$PWD"
    for (( n=${#slashes}; n>0; --n ))
    do
        test -e "$directory/.gitconfig" && echo "$directory/.gitconfig" && return 
        directory="$directory/.."
    done
}


alias git='__recursive_gitconfig_git'

Although most questions sort of answered the OP, I just had to go through this myself and without even googling I was able to find the quickest and simplest solution. Here's simple steps:

• copy existing .gitconfg from your other repo
• paste into your newly added repo
• change values in .gitconfig file, such as name, email and username

  [user]
  	name = John
  	email = [email protected]
  	username = john133
  

• add filename to .gitignore list, to make sure you don't commit .gitconfig file to your work repo

You can also use git commit --author "Your Name <[email protected]>" at the moment of doing a commit in a repo where you want to commit as a different user.

Prior to following the below steps, you must have multiple ssh keys. Those can be generated using here command

Steps

1. Go to c:\users\Your User\.ssh
2. touch config
3. Configure ssh keys per domain

4. Go to git repo using gitbash.
5. Configure username and name per repo "git config user.email="[email protected]"
6. Configure name per repo. git config user.name="Mo Sh"
7. Execute git commands. it would pick SSH keys automatically.

Something like Rob W's answer, but allowing different a different ssh key, and works with older git versions (which don't have e.g. a core.sshCommand config).

I created the file ~/bin/git_poweruser, with executable permission, and in the PATH:

#!/bin/bash

TMPDIR=$(mktemp -d)
trap 'rm -rf "$TMPDIR"' EXIT

cat > $TMPDIR/ssh << 'EOF'
#!/bin/bash
ssh -i $HOME/.ssh/poweruserprivatekey $@
EOF

chmod +x $TMPDIR/ssh
export GIT_SSH=$TMPDIR/ssh

git -c user.name="Power User name" -c user.email="[email protected]" $@

Whenever I want to commit or push something as "Power User", I use git_poweruser instead of git. It should work on any directory, and does not require changes in .gitconfig or .ssh/config, at least not in mine.

Just add this to your ~/.bash_profile to switch between default keys for github.com

# Git SSH keys swap
alias work_git="ssh-add -D  && ssh-add -K ~/.ssh/id_rsa_work"
alias personal_git="ssh-add -D && ssh-add -K ~/.ssh/id_rsa"

There can be multiple ways to do this, but I'm achieving this via the below shell function.

function gitprofile() {
    if [[ $1 == "private" ]]; then
        if grep -q "[email protected]" "/Users/tomtaylor/.gitconfig"; then
            echo "Found in gitconfig. No action required."
        else 
            echo "Found in gitconfig1"
            cp /Users/tomtaylor/.gitconfig /Users/tomtaylor/.gitconfig2
            mv /Users/tomtaylor/.gitconfig1 /Users/tomtaylor/.gitconfig
            mv /Users/tomtaylor/.gitconfig2 /Users/tomtaylor/.gitconfig1
        fi
    elif [[ $1 == "public" ]]; then
        if grep -q "[email protected]" "/Users/tomtaylor/.gitconfig"; then
            echo "Found in gitconfig. No action required."
        else 
            echo "Found in gitconfig1"
            cp /Users/tomtaylor/.gitconfig /Users/tomtaylor/.gitconfig2
            mv /Users/tomtaylor/.gitconfig1 /Users/tomtaylor/.gitconfig
            mv /Users/tomtaylor/.gitconfig2 /Users/tomtaylor/.gitconfig1
        fi
}

Invoking it like,

gitprofile "public" -> This would switch to profile with [email protected] and

gitprofile "private" -> This would switch to [email protected].

Add this function to your ~/.bash_profile or ~/.zshrc based on your current terminal preference. Restart the terminal or just compile the script like

> . ~/.bash_profile

to make the function effective. Hope it helps !

Let's redefine the specs - you just want to be able to use multiple identities with git against different organisations - all you need is 2 oneliners:

 # generate a new private public key pair for org1  
 [email protected];ssh-keygen -t rsa -b 4096 -C $email -f $HOME/.ssh/id_rsa.$email

 # use org1 auth in THIS shell session - Ctrl + R, type org1 in new one 
 [email protected];export GIT_SSH_COMMAND="ssh -p 22 -i ~/.ssh/id_rsa.$email"

Why I know that this is by far the most simple solution:

  # me using 9 different orgs with separate git auths dynamically
  find $HOME/.ssh/id_rsa.*@* | wc -l
  18