gistfile1.sh

#!/bin/bash

REMOTE=${GERRIT:-gerrit}
GERRIT_NUMBER=$1
REV_A=$2
REV_B=$3

if ! [[ "$GERRIT_NUMBER" =~ "[0-9]+" ]] || \
   ! [[ "$REV_A" =~ "[0-9]+" ]] || \
   ! [[ "$REV_B" =~ "[0-9]+" ]] ; then
  echo "usage: $0 <gerrit number> <rev 1> <rev 2>"
  echo
  echo eg: $0 12345 1 3
  echo    will show the diff between revision 1 and 3 of gerrit #12345
fi

last_two_digits=$(echo $GERRIT_NUMBER | tail --bytes=3)

set -e
git fetch $REMOTE refs/changes/$last_two_digits/$GERRIT_NUMBER/$REV_A
git format-patch -1 --stdout FETCH_HEAD > /tmp/$GERRIT_NUMBER.$REV_A.patch
git fetch $REMOTE refs/changes/$last_two_digits/$GERRIT_NUMBER/$REV_B
git format-patch -1 --stdout FETCH_HEAD > /tmp/$GERRIT_NUMBER.$REV_B.patch

diff /tmp/$GERRIT_NUMBER.{$REV_A,$REV_B}.patch