[edit] check also this answer to have a quick overview of how much is different between your two remotes.
If you have a local clone with the two repositories set as remote (using for example @jingx's answer), you can write a script to check what branches can be pushed to new :
(note : I will keep the names new and old as @jginx suggested to name the two remotes, you want to update branches in new with data from old ; in the scripts below, you may want to search&replace new with origin, and old with whatever name you chose for the remote that points to the decomissioned repo )
git for-each-ref allows you to list all the existing branch names :
# the following will list all the branch names coming from 'old', without
# the leading 'old/' prefix (e.g : 'old/master' will be listed as 'master') :
git for-each-ref refs/remotes/old --format="%(refname:lstrip=3)"
git rev-parse --verify [refname] allows you to check if a ref exists :
if git rev-parse -q --verify new/$branchname > /dev/null; then
echo "$branchname exists on new repo"
else
echo "$branchname needs to be created on new repo"
fi
git merge-base --is-ancestor [ref1] [ref2] allows you to check if ref1 is an ancestor of ref2 (and hence : if ref1 can be fast forwarde to ref2) :
if git merge-base --is-ancestor new/$branchname old/$branchname; then
echo "old/$branchname can be pushed to new repo as is"
else
echo "old/$branchname and new/$branchname need to be merged,"
echo " or old/$branchname needs to be force pushed"
echo " or ignored ..."
fi
[ $(git rev-parse [ref1]) != $(git rev-parse [ref2]) ] allows you to check if two refs point at different commits
Here is an example script which puts these pieces together :
# file check.sh :
#!/bin/bash
branchname=$1
# if new/branchname does not exist: list it as a branch to be created
if ! git rev-parse -q --verify new/$branchname > /dev/null; then
echo "git push new old/$branchname:refs/heads/$branchname # create"
# if new/$branchname exists : check if it can be fast forwarded to old/$branchname
elif git merge-base --is-ancestor new/$branchname old/$branchname; then
# check if the two branches are different :
if [ $(git rev-parse old/$branchname) != $(git rev-parse new/$branchname) ]; then
echo "git push new old/$branchname:refs/heads/$branchname # update"
fi
# otherwise : nothing to do
else
echo "# needs merging : new/$branchname and old/$branchname"
fi
sample usage :
git for-each-ref refs/remotes/old --format="%(refname:lstrip=3)" | while read branchname; do
bash check.sh $branchname
done > actions.sh
actions.sh is now a file, which contains a list of some actions to perform ; you can review it, and choose what should be applied and ignored.
If you edit it in place (e.g : delete or comment the lines you want to ignore), you can simply run it by calling bash actions.sh.
