git submodule update vs git submodule sync
git documentation doesn’t make it at all clear what the difference is between a
git submodule update and a
git submodule sync is. I’m also not finding any help out on the web. Can someone help me out with what the difference is here?
update Update the registered submodules to match what the superproject expects by cloning missing submodules and updating the working tree of the submodules. The "updating" can be done in several ways depending on command line options and the value of submodule.<name>.update configuration variable.
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sync Synchronizes submodules' remote URL configuration setting to the value specified in .gitmodules. It will only affect those submodules which already have a URL entry in .git/config (that is the case when they are initialized or freshly added). This is useful when submodule URLs change upstream and you need to update your local repositories accordingly.
For reference, I’m using the git client version 2.11.0
2 Solutions collect form web for “git submodule update vs git submodule sync”
git submodule update updates the contents of the submodules. It is effectively running a “git fetch” and “git checkout” in each of your submodules.
git submodule sync updates the metadata about a submodule to reflect changes in the submodule URL. It re-synchronizes the information in
.git/config with the information in
update is basically doing
git pull in each submodule (except without a branch, since the main repo specifies a commit directly).
The tricky one is
sync. Imagine you clone a project with submodules, then later the upstream project changes one of the submodules to point to a different URL.
Your local copy of the submodule will still point to the old URL, since git never allows remote repositories to force a change to local configuration. You need to run
git submodule sync to apply the remote repo’s configuration to your local submodule repos.
Note also that, if you are making changes to the submodules, you might want the URLs to mismatch even if the upstream never changed them … but using multiple remote URLs is probably a better idea for that case.