Take a username and back up all of their git repos. Works for organizations as well.

github_backup.sh

#!/bin/bash
set -e

if [ -z $2 ]
then
	TYPE=users
else
	TYPE=orgs
fi

if [ -z $1 ]
then
	echo "Need to specify Github Username to back up."
	echo "Usage:
	github_backup <username>
	github_backup <organization name> org"
	exit 1
else
	echo "Backing up $1's git repos"
	if [ ! -d $1 ]
	then
		mkdir $1
	fi
	cd $1
fi
REPOLIST=`python -c "import requests
for repo in requests.get('https://api.github.com/$TYPE/$1/repos').json:
	print repo['git_url']"`

for R in $REPOLIST
do
	if [ -d `echo $R | sed -e 's/.*\/\([^/]\)/\1/'` ]
	then
		echo "Already have $R saved"
	else
		git clone --mirror $R
		echo "Backed up $R"
	fi
done

for N in `ls`
do
	cd $N
	git fetch -q
	cd ..
	echo "Updated $N"
done