Continue looping over submodules with the "git submodule foreach" command after a non-zero exit

Question

Just make your command always return a 0 code like so:

git submodule foreach 'npm install || :'

This is taken from the manual: git help submodule:

   foreach
       Evaluates an arbitrary shell command in each checked out submodule.
       The command has access to the variables $name, $path, $sha1 and
       $toplevel: $name is the name of the relevant submodule section in
       .gitmodules, $path is the name of the submodule directory relative
       to the superproject, $sha1 is the commit as recorded in the
       superproject, and $toplevel is the absolute path to the top-level
       of the superproject. Any submodules defined in the superproject but
       not checked out are ignored by this command. Unless given --quiet,
       foreach prints the name of each submodule before evaluating the
       command. If --recursive is given, submodules are traversed
       recursively (i.e. the given shell command is evaluated in nested
       submodules as well). A non-zero return from the command in any
       submodule causes the processing to terminate. This can be
       overridden by adding || : to the end of the command.

       As an example, git submodule foreach 'echo $path `git rev-parse
       HEAD`' will show the path and currently checked out commit for each
       submodule.

The command : from help : in bash:

:: :
    Null command.

    No effect; the command does nothing.

    Exit Status:
    Always succeeds.

Always succeeds :)

You could see this topic.

I don't use GIT, but if you can locate the .gitmodules files, it may be easy to loop for each submodules :

<command to find all of your submodules>|while read; do
    # ... (default use $REPLY as an item)
done

Or :

while read; do
    # ...
done <<< "$(command to find all of your submodules)"

See this reminder on how to read a command output with a loop in Bash.