Step 1, install curl, git, and make (or run linux)
Step 2. Use this makefile:
NAME := $(shell whoami)
TARGET := users
PAGE := 1
MAX := 1000
all: $(TARGET)
users: CTNX=users
users: clone wikis
orgs: CTNX=orgs
orgs: clone wikis
$(NAME):
@mkdir $@
clone: $(NAME)
-$(shell cd $(NAME); curl -sSLk "https://api.github.com/$(CTNX)/$(NAME)/repos?page=$(PAGE)&per_page=$(MAX)" | grep -e 'git_url*' | cut -d\" -f4 | xargs -L1 -P3 git clone -q)
wikis: $(NAME)
-$(shell cd $(NAME); curl -sSLk "https://api.github.com/$(CTNX)/$(NAME)/repos?page=$(PAGE)&per_page=$(MAX)" | grep -e 'git_url*' | sed 's/\.git/.wiki.git/'| cut -d\" -f4 | xargs -L1 -P3 git clone -q)
Step 3. Execute make NAME=<your github username || orgname > TARGET=<users || orgs>
Step 4. Store all the code somewhere’s safe. Archive.org is a nice choice.