git-fixup

#!/bin/sh
#
# script to simplify jumping back during interactive rebase (or to start an interactive rebase)
#
# see also:
# https://stackoverflow.com/questions/69673695/git-jump-back-again-during-interactive-rebase
#

set -e

if [ "$GIT_SEQUENCE_EDITOR" == "$(readlink -f $0)" ]; then
    # mark the first rev as a patch to edit (the one that's passed to the fixup script)
    # see also below
    sed -i -e '1 s#^p #e #' "$1"
    sed -i -e '1 s#^pick #edit #' "$1"
    exit
fi

fixup_rev="$1"
shift 1

fixup_rev_pretty=$(git rev-parse "$fixup_rev")

rebase_merge_path="$(git rev-parse --show-toplevel)/.git/rebase-merge"
rebase_todo="$rebase_merge_path/git-rebase-todo"
rebase_done="$rebase_merge_path/done"

if [ ! -f "$rebase_todo" ]; then
    # set us ourselves as sequence editor to mark the passed patch for edito automatically
    # see also above
    GIT_SEQUENCE_EDITOR="$(readlink -f $0)" git rebase --interactive "$fixup_rev"
    exit
fi

if ! grep -q "$fixup_rev_pretty" "$rebase_done"; then
    echo "rev $fixup_rev aka $fixup_rev_pretty not listed in $rebase_done"
    echo "Cannot fixup outside of current interactive rebase range."
    echo "You'll have to finish the ongoing rebase first and restart with a range that includes $rev afterwards"
    exit
fi

scratch="$rebase_todo.tmp"
git log --format=format:"%H %s" "$fixup_rev"..HEAD | awk '{print "pick " $0}' > "$scratch"
echo "break" >> "$scratch"
cat "$rebase_todo" >> "$scratch"

cp "$rebase_todo" "$rebase_todo.backup"
mv "$scratch" "$rebase_todo"

git checkout "$fixup_rev"

echo "You can amend the commit now, with"
echo
echo "  git commit --amend"
echo
echo "Once you are satisfied with your changes, run"
echo
echo "  git rebase --continue"