How to reduce the depth of an existing git clone?

Question

I have a clone. I want to reduce the history on it, without cloning from scratch with a reduced depth. Worked example:

$ git clone git@github.com:apache/spa         


        

Answer 1

OK here's an attempt to bash it, that ignores non-default branches, and also assumed the remote is called 'origin':

#!/bin/sh

set -e

mkdir .git_slimmer

cd $1

changed_lines=$(git status --porcelain | wc -l)
ahead_of_remote=$(git status | grep "Your branch is ahead" | wc -l)
remote_url=$(git remote show origin  | grep Fetch | cut -d' ' -f5)
latest_sha=$(git log | head -n 1 | cut -d' ' -f2)

cd ..

if [ "$changed_lines" -gt "0" ]
then
  echo "Untracked Changes - won't make the clone slimmer in that situation"
  exit 1
fi

if [ "$ahead_of_remote" -gt "0" ]
then
  echo "Local commits not in the remote - won't make the clone slimmer in that situation"
  exit 1
fi

cd .git_slimmer
git clone $remote_url --no-checkout --depth 1 foo
cd foo
latest_sha_for_new=$(git log | head -n 1 | cut -d' ' -f2)
cd ../..

if [ "$latest_sha" == "$latest_sha_for_new" ]
then
  mv "$1/.git" "$1/.gitOLD"
  mv ".git_slimmer/foo/.git" "$1/"
  rm -rf "$1/.gitOLD"
  cd "$1"
  git add .
  cd ..
else
  echo "SHA from head of existing get clone does not match the latest one from the remote: do a git pull first"
  exit 1
fi

rm -rf .git_slimmer

Use: 'git-slimmer.sh '