pull_all_git_branches.sh

#!/bin/bash

###############################################################################
# File:   pull_all_git_branches.sh
# Author: Alex Hogen (@ahogen on Github)
#
# Iterate through all cloned git repositories in this directory and update
# (pull) all their branches to sync with their remote counterparts.
#
# In diagram below, if this script is executed from <this dir>, then all repositories
# in the subdirectories will be updated.
#
# <this dir>
#  |
#   --- git_repo_1
#  |
#   --- git_repo_2
#  |
#   --- git_repo_3
###############################################################################

# https://stackoverflow.com/questions/4000613/bash-for-each-directory
for D in *; do
    if [ -d "${D}" ]; then
        echo "${D}"   # your processing here
        cd "${D}"
        # https://stackoverflow.com/questions/10312521/how-to-fetch-all-git-branches
        git branch -r | grep -v '\->' | while read remote; do git branch --track "${remote#origin/}" "$remote"; done
        git fetch --all
        git pull --all
        cd -
    fi
done