➜  nuttx-forgejo git:(main) ✗ $ docker exec \
  -it \
  forgejo \
  /bin/bash -c \
  "tar cvf /tmp/data.tar /data"

tar: removing leading '/' from member names
data/
data/git/
data/git/repositories/
data/git/repositories/nuttx/
data/git/repositories/nuttx/nuttx-mirror.git/
data/git/repositories/nuttx/nuttx-mirror.git/logs/
data/git/repositories/nuttx/nuttx-mirror.git/logs/HEAD
data/git/repositories/nuttx/nuttx-mirror.git/HEAD
data/git/repositories/nuttx/nuttx-mirror.git/hooks/
data/git/repositories/nuttx/nuttx-mirror.git/hooks/sendemail-validate.sample
data/git/repositories/nuttx/nuttx-mirror.git/hooks/prepare-commit-msg.sample
data/git/repositories/nuttx/nuttx-mirror.git/hooks/applypatch-msg.sample
data/git/repositories/nuttx/nuttx-mirror.git/hooks/pre-receive.sample
data/git/repositories/nuttx/nuttx-mirror.git/hooks/pre-push.sample
data/git/repositories/nuttx/nuttx-mirror.git/hooks/pre-applypatch.sample
data/git/repositories/nuttx/nuttx-mirror.git/hooks/pre-commit.sample
data/git/repositories/nuttx/nuttx-mirror.git/hooks/post-update.sample
data/git/repositories/nuttx/nuttx-mirror.git/hooks/push-to-checkout.sample
data/git/repositories/nuttx/nuttx-mirror.git/hooks/update.sample
data/git/repositories/nuttx/nuttx-mirror.git/hooks/pre-rebase.sample
data/git/repositories/nuttx/nuttx-mirror.git/hooks/commit-msg.sample
data/git/repositories/nuttx/nuttx-mirror.git/hooks/pre-merge-commit.sample
data/git/repositories/nuttx/nuttx-mirror.git/info/
data/git/repositories/nuttx/nuttx-mirror.git/info/refs
data/git/repositories/nuttx/nuttx-mirror.git/info/exclude
data/git/repositories/nuttx/nuttx-mirror.git/description
data/git/repositories/nuttx/nuttx-mirror.git/refs/
data/git/repositories/nuttx/nuttx-mirror.git/refs/heads/
data/git/repositories/nuttx/nuttx-mirror.git/refs/tags/
data/git/repositories/nuttx/nuttx-mirror.git/refs/remotes/
data/git/repositories/nuttx/nuttx-mirror.git/git-daemon-export-ok
data/git/repositories/nuttx/nuttx-mirror.git/packed-refs
data/git/repositories/nuttx/nuttx-mirror.git/branches/
data/git/repositories/nuttx/nuttx-mirror.git/config
data/git/repositories/nuttx/nuttx-mirror.git/objects/
data/git/repositories/nuttx/nuttx-mirror.git/objects/pack/
data/git/repositories/nuttx/nuttx-mirror.git/objects/pack/pack-cd5d5fecd284e8b37ff82a3fe9143f13372e0e97.rev
data/git/repositories/nuttx/nuttx-mirror.git/objects/pack/pack-cd5d5fecd284e8b37ff82a3fe9143f13372e0e97.pack
data/git/repositories/nuttx/nuttx-mirror.git/objects/pack/pack-cd5d5fecd284e8b37ff82a3fe9143f13372e0e97.idx
data/git/repositories/nuttx/nuttx-mirror.git/objects/info/
data/git/repositories/nuttx/nuttx-mirror.git/objects/info/packs
data/git/repositories/nuttx/nuttx-mirror.git/objects/info/commit-graph
data/git/repositories/nuttx/nuttx-update.git/
data/git/repositories/nuttx/nuttx-update.git/logs/
data/git/repositories/nuttx/nuttx-update.git/logs/HEAD
data/git/repositories/nuttx/nuttx-update.git/HEAD
data/git/repositories/nuttx/nuttx-update.git/hooks/
data/git/repositories/nuttx/nuttx-update.git/hooks/sendemail-validate.sample
data/git/repositories/nuttx/nuttx-update.git/hooks/prepare-commit-msg.sample
data/git/repositories/nuttx/nuttx-update.git/hooks/proc-receive.d/
data/git/repositories/nuttx/nuttx-update.git/hooks/proc-receive.d/gitea
data/git/repositories/nuttx/nuttx-update.git/hooks/pre-receive.d/
data/git/repositories/nuttx/nuttx-update.git/hooks/pre-receive.d/gitea
data/git/repositories/nuttx/nuttx-update.git/hooks/post-receive
data/git/repositories/nuttx/nuttx-update.git/hooks/applypatch-msg.sample
data/git/repositories/nuttx/nuttx-update.git/hooks/pre-receive.sample
data/git/repositories/nuttx/nuttx-update.git/hooks/pre-push.sample
data/git/repositories/nuttx/nuttx-update.git/hooks/pre-applypatch.sample
data/git/repositories/nuttx/nuttx-update.git/hooks/update.d/
data/git/repositories/nuttx/nuttx-update.git/hooks/update.d/gitea
data/git/repositories/nuttx/nuttx-update.git/hooks/pre-commit.sample
data/git/repositories/nuttx/nuttx-update.git/hooks/pre-receive
data/git/repositories/nuttx/nuttx-update.git/hooks/post-update.sample
data/git/repositories/nuttx/nuttx-update.git/hooks/proc-receive
data/git/repositories/nuttx/nuttx-update.git/hooks/push-to-checkout.sample
data/git/repositories/nuttx/nuttx-update.git/hooks/update.sample
data/git/repositories/nuttx/nuttx-update.git/hooks/update
data/git/repositories/nuttx/nuttx-update.git/hooks/pre-rebase.sample
data/git/repositories/nuttx/nuttx-update.git/hooks/commit-msg.sample
data/git/repositories/nuttx/nuttx-update.git/hooks/pre-merge-commit.sample
data/git/repositories/nuttx/nuttx-update.git/hooks/post-receive.d/
data/git/repositories/nuttx/nuttx-update.git/hooks/post-receive.d/gitea
data/git/repositories/nuttx/nuttx-update.git/info/
data/git/repositories/nuttx/nuttx-update.git/info/refs
data/git/repositories/nuttx/nuttx-update.git/info/exclude
data/git/repositories/nuttx/nuttx-update.git/description
data/git/repositories/nuttx/nuttx-update.git/refs/
data/git/repositories/nuttx/nuttx-update.git/refs/heads/
data/git/repositories/nuttx/nuttx-update.git/refs/tags/
data/git/repositories/nuttx/nuttx-update.git/refs/remotes/
data/git/repositories/nuttx/nuttx-update.git/git-daemon-export-ok
data/git/repositories/nuttx/nuttx-update.git/packed-refs
data/git/repositories/nuttx/nuttx-update.git/branches/
data/git/repositories/nuttx/nuttx-update.git/config
data/git/repositories/nuttx/nuttx-update.git/objects/
data/git/repositories/nuttx/nuttx-update.git/objects/pack/
data/git/repositories/nuttx/nuttx-update.git/objects/pack/pack-11d743301777246ce111d9108ffcc710b1a5cc2b.rev
data/git/repositories/nuttx/nuttx-update.git/objects/pack/pack-11d743301777246ce111d9108ffcc710b1a5cc2b.idx
data/git/repositories/nuttx/nuttx-update.git/objects/pack/pack-11d743301777246ce111d9108ffcc710b1a5cc2b.pack
data/git/repositories/nuttx/nuttx-update.git/objects/info/
data/git/repositories/nuttx/nuttx-update.git/objects/info/packs
data/git/repositories/nuttx/nuttx-update.git/objects/info/commit-graph
data/git/lfs/
data/git/.ssh/
data/git/.ssh/environment
data/git/.ssh/authorized_keys
data/gitea/
data/gitea/home/
data/gitea/home/.gitconfig
data/gitea/actions_log/
data/gitea/repo-archive/
data/gitea/log/
data/gitea/tmp/
data/gitea/tmp/package-upload/
data/gitea/repo-avatars/
data/gitea/avatars/
data/gitea/avatars/tmp/
data/gitea/avatars/3fc75f3ae192197fc2e782883843f319
data/gitea/gitea.db
data/gitea/packages/
data/gitea/queues/
data/gitea/queues/common/
data/gitea/queues/common/LOCK
data/gitea/queues/common/MANIFEST-000000
data/gitea/queues/common/000001.log
data/gitea/queues/common/LOG
data/gitea/queues/common/CURRENT
data/gitea/attachments/
data/gitea/indexers/
data/gitea/indexers/issues.bleve/
data/gitea/indexers/issues.bleve/index_meta.json
data/gitea/indexers/issues.bleve/store/
data/gitea/indexers/issues.bleve/store/root.bolt
data/gitea/indexers/issues.bleve/rupture_meta.json
data/gitea/conf/
data/gitea/conf/app.ini
data/gitea/actions_artifacts/
data/gitea/jwt/
data/gitea/jwt/private.pem
data/gitea/sessions/
data/gitea/sessions/0/
data/gitea/sessions/0/b/
data/gitea/sessions/3/
data/gitea/sessions/3/c/
data/gitea/sessions/3/c/3cbe353d1cd1a022
data/gitea/sessions/5/
data/gitea/sessions/5/8/
data/ssh/
data/ssh/ssh_host_ecdsa_key.pub
data/ssh/ssh_host_rsa_key
data/ssh/ssh_host_ecdsa_key
data/ssh/ssh_host_rsa_key.pub
data/ssh/ssh_host_ed25519_key
data/ssh/ssh_host_ed25519_key.pub

➜  nuttx-forgejo git:(main) ✗ $ docker cp \   
  forgejo:/tmp/data.tar \
  .
Successfully copied 843MB to /Users/luppy/nuttx-forgejo/.