git-sync

#!/bin/bash

set -e

if ! git rev-parse --is-inside-work-tree &>/dev/null; then
  echo "Not a git repository."
  exit 1
fi

if [ "$1" = "-h" ]; then
    cat <<EOF
usage: git-sync [-n] [BRANCH [UPSTREAM [TARGET]]]

switch to BRANCH, fetch from UPSTREAM, merge it to UPSTREAM/BRANCH,
push it to TARGET, switch back to the current branch (unless -n is given).

BRANCH defaults to "master", UPSTREAM to "upstream", and TARGET to "origin".
EOF
    exit 0
fi

n=""
if [ "$1" = "-n" ]; then
    n=1
    shift
fi

b="${1:-master}"
r="${2:-upstream}"
p="${3:-origin}"

cb="$(git rev-parse --abbrev-ref HEAD)"

if [ "$cb" != "$b" ]; then
    git checkout "$b"
fi

git fetch "$r" && git merge "$r"/"$b" && git push "$p"

if [ -z "$n" -a "$cb" != "$b" ]; then
    git checkout "$cb"

    read -e -n 1 -p "Rebase or Merge? [r/m/N] "
    case "$REPLY" in
        r|R)
            git rebase "$b"
            ;;
        m|M)
            git merge "$b"
            ;;
    esac
fi