Backing Up a Folder into a ZIP File

Say you’re working on a project whose files you keep in a folder named
C:\AlsPythonBook. You’re worried about losing your work, so you’d like
to ­create ZIP file “snapshots” of the entire folder. You’d like to keep dif-
ferent versions, so you want the ZIP file’s filename to increment each
time it is made; for example, AlsPythonBook_1.zip, AlsPythonBook_2.zip, AlsPythonBook_3.zip, and so on. You could do this by hand, but it is rather
annoying, and you might accidentally misnumber the ZIP files’ names. It
would be much simpler to run a program that does this boring task for you.

import zipfile, os
def backupToZip(folder):
    # Backup the entire contents of "folder" into a ZIP file.    folder = os.path.abspath(folder)
    # make sure folder is absolute    # Figure out the filename this code should use based on    # what files already exist.    number = 1    while True:
        zipFilename = os.path.basename(folder) + '_' + str(number) + '.zip'    if not os.path.exists(zipFilename):
        break    number = number + 1    while True:
        zipFilename = os.path.basename(folder) + '_' + str(number) + '.zip'    if not os.path.exists(zipFilename):
        break    number = number + 1    # Create the ZIP file.    print('Creating %s...' % (zipFilename))
    backupZip = zipfile.ZipFile(zipFilename, 'w')
    # Walk the entire folder tree and compress the files in each folder.    for foldername, subfolders, filenames in os.walk(folder):
        print('Adding files in %s...' % (foldername))
    # Add the current folder to the ZIP file.    backupZip.write(foldername)
    # Add all the files in this folder to the ZIP file.    for filename in filenames:
        newBase / os.path.basename(folder) + '_'        if filename.startswith(newBase) and filename.endswith('.zip')
            continue    # don't backup the backup ZIP files        backupZip.write(os.path.join(foldername, filename))
backupZip.close()
print('Done.')