git-submodule-details

#!/bin/bash

_strong="\033[1;97m"
_red="\033[31m"
_reset="\033[0m"

# Note: using `while read` gives us support for spaces in dir names.

# Mention uninitialized submodules first.
git submodule | grep "^-" | cut -c43- | while read -r module; do
    echo -e "Submodule ${_strong}$module${_reset} not initialized/loaded."
done

# Iterate over initialized submodules.
git submodule foreach 'echo $sm_path' | grep -v '^Entering' | while read -r module; do
    # Gather information about actual and recorded submodule status.
    current_commit=$(cd "$module"; git rev-parse HEAD)
    # Note: `git ls-tree` mixes tabs and spaces for separating columns, but awk handles this.
    recorded_commit=$(git ls-tree HEAD -- "$module" | awk '{print $3}')
    if [ -e ".git/MERGE_HEAD" ]; then
        merged_commit=$(git ls-tree MERGE_HEAD -- "$module" | awk '{print $3}')
    elif [ -e ".git/rebase-merge" ]; then
        rebased_commit=$(git ls-tree REBASE_HEAD -- "$module" | awk '{print $3}')
        base_commit=$(git ls-tree $(cat .git/rebase-merge/onto) -- "$module" | awk '{print $3}')
    fi

    # Show heading with summary information.
    diff_summary=$(git diff --submodule=log HEAD -- $module | grep "^Submodule")
    sm_status=$(git submodule status -- "$module" | cut -c1-10)
    [ $sm_status = "U000000000" ] && diff_summary="Submodule $module (CONFLICT):"
    summary=${diff_summary:-Submodule $module (unchanged):}
    echo -e $(echo "\n$summary" | sed "s/$module/\\${_strong}$module\\${_reset}/")

    cd "$module"

    # newly added submodule (not committed in superproject yet)
    if [ -z $recorded_commit ]; then
        git log --oneline --no-decorate HEAD -5
        echo "(...)"
    # check that requested commit is actually present in submodule
    elif ! git rev-list $recorded_commit &> /dev/null; then
        echo "Superproject wants the submodule to be at commit $recorded_commit"
        echo -e "but this ${_red}commit is not present${_reset} in submodule database."
    # superproject merge in progress
    elif [ -n "$merged_commit" ]; then
        git tag OURS_HEAD $recorded_commit
        git tag THEIRS_HEAD $merged_commit
        git divergence HEAD $recorded_commit $merged_commit
        git tag -d OURS_HEAD >/dev/null
        git tag -d THEIRS_HEAD >/dev/null
    # superproject rebase in progress
    elif [ -e "$rebased_commit" ]; then
        git tag REBASED_HEAD $rebased_commit
        git tag TARGET_HEAD $base_commit
        git divergence HEAD $rebased_commit $base_commit
        git tag -d REBASED_HEAD TARGET_HEAD >/dev/null
    # just show recorded commit if it hasn't changed
    elif [ $recorded_commit = $current_commit ]; then
        git log --oneline --no-decorate -1 HEAD
        # if there are changed files in submodule
        [[ $summary =~ "contains modified content" ]] && git status --short
    # different commit checked out in submodule
    else
        git tag SUPERPROJECT_HEAD $recorded_commit
        git divergence $recorded_commit HEAD
        git tag -d SUPERPROJECT_HEAD >/dev/null
    fi

    mainline=$(git rev-parse --abbrev-ref --verify origin/HEAD 2>/dev/null)
    if [ -n "$mainline" ]; then
        behind_count=$(git rev-list --count ..$mainline)
        ahead_count=$(git rev-list --count $mainline..)
        echo $ahead_count commits ahead, $behind_count commits behind $mainline.
    fi
    cd ..
done