Change git identity

gistfile1.txt

In your config add sections for user-$IDENTITY. Below I use -work and -home
Also add an alias to run a script when you want to change .. I chose "user" ... "become" might be fun...

$ cat ~/.gitconfig
<---------snip---------->
[user]
        name = David Greaves
        email = david.greaves@jolla.com
[user-home]
        name = David Greaves
        email = david@dgreaves.com
[user-work]
        name = David Greaves
        email = david.greaves@jolla.com
[alias]
        user = !/home/david/.gitconfig.d/change_user.sh
<---------snip---------->

Then add this script (and make it executable):

mkdir -p ~/.gitconfig.d
cat <<EOF > ~/.gitconfig.d/change_user.sh
#!/bin/bash
src=$1
if [[ $src == "" ]]; then
    # Who am I?
    git config --global --get user.name
    git config --global --get user.email
else
    # Alter ego...
    git config --global user.name "$(git config --global user-${src}.name)"
    git config --global user.email "$(git config --global user-${src}.email)"
fi
EOF
chmod +x ~/.gitconfig.d/change_user.sh