Apply messages from provided input file to git commits with empty messages

git-unvoid-messages

#!/bin/sh
# Apply messages from provided input file to commits with empty messages
# The messages are applied in inverse order (first line in the file applied to older commit with void message)
# and only up to the number of commits with empty messages.
#
# This action is destructive to your repo's history. It's best to do this on a clone,
# just in case. Also beware that this should not be performed on a repo that has been
# shared with others without forcing them to reset their history.
#
# Use at your own risk.
#
# Put the script in your path and invoke it this way:
# git unvoid-messages <inputfile>

if [[ ! -n $1 ]]; then
  echo "usage: git unvoid-messages <inputfile>\n"
  exit 1
fi


echo "Unvoiding messages with contens from $1..."

cp $1 $1.tmp
export input_file=$PWD/$1.tmp

git filter-branch -f --msg-filter '

read msg
if [ -z "$msg" ]; then
  msg=`head -n 1 $input_file`
  sed -i "" -e "1d" $input_file
fi
echo "$msg"
'

rm $1.tmp
unset input_file

[[ $? -eq 0 ]] && echo Done!
[[ $? -ne 0 ]] && echo Error!