set_timestamp_from_commit.sh

#!/bin/sh
OS=${OS:-`uname`}
 
if   [ "$OS" = 'Linux' ]
then
    update_file_timestamp() {
        file_time=`git log --no-merges --format=%ai "$1" | head -n 1`
        echo "change timestamp file $file_time $1"
        touch -d "$file_time" "$1"
    }
elif [ "$OS" = 'FreeBSD' ] || [ "$OS" = 'Darwin' ];
then
    update_file_timestamp() {
        file_time=`date -r "$(git log --no-merges --format=%at "$1" | head -n 1)" '+%Y%m%d%H%M.%S'`
        echo "change timestamp file $file_time $1"
        touch -h -t "$file_time" "$1"
    }
else
    echo "timestamp changing not implemented" >&2
    exit 1
fi

#List all the files of the git repository
for file in `git ls-tree -r --name-only HEAD`
do
    if [ -f "$file" ]; then
        #For each file update the file timestamp with the timestamp of the last commit on this file
        update_file_timestamp "$file"
    fi
done