Figured an easy way to update a lot of checked out Git repositories in a given subtree (or whatever default you set in line 3).

gitupdate.sh

# This assumes I am using zsh, and git config --global pull.rebase true

function gitupdate () {
# https://unix.stackexchange.com/questions/333862/how-to-find-all-git-repositories-within-given-folders-fast
        find ${1:-.} -type d -path '*/.git' -printf '%h\n' -prune | xargs -t -I{} zsh -c "pushd {} && git fetch -p && git rev-parse --abbrev-ref --symbolic-full-name @{u} &&
git pull ; popd"
        git fetch -p && git pull
}

function gclone () {
        pushd ~/src
        git clone https://mylogin@git.server.example.com/gitrepos/${1}.git
        popd
}

cdpath+=(~/src)
alias gitcd='cd $(git rev-parse --show-toplevel)'