unixorn/git-extra-commands

#!/bin/sh -e
# git neck [-r] [COMMIT] - show commits until first branching point
#
# Source: https://leahneukirchen.org/blog/archive/2013/01/a-grab-bag-of-git-tricks.html

[ "$1" = -r ] && shift && R=-r
COMMIT=$(git rev-parse --no-flags --default HEAD "$@")

# skip first elements of trail
TORSO=$(git trail "$R" "$COMMIT" | cut -d' ' -f2 | uniq | sed -n 2p)

# fall back to initial commit on empty trail
# shellcheck disable=SC2046,SC2086
: ${TORSO:=$(git rev-list --max-parents=0 HEAD)}

# shellcheck disable=SC2046,SC2086
exec git log --oneline $(git rev-parse --no-revs "$@") $COMMIT...$TORSO