Created
October 29, 2018 18:35
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Simple backup class
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| #!/usr/bin/env python3 | |
| import os | |
| import shutil | |
| class Backer: | |
| """Implements a backup strategy for a file. You might | |
| use this when preparing to overwrite an important configuration | |
| or log file that's not under version control.""" | |
| def __init__(self, filename): | |
| """Create a new instance for a given file | |
| :param filename the full path to the file to be backed up. | |
| Backups will be created in the same directory.""" | |
| self.base = os.path.basename(filename) | |
| self.orig = filename | |
| self.rpr = re.compile(f"{re.escape(self.base)}\\.?(\\d+)?") | |
| def backup(self, retain=5): | |
| """Backs up the file and rotates previous backups, | |
| retaining a specified number of previous backups. | |
| Copies the existing file to `filename.1`, and copies | |
| existing backups to the next higher backup number, | |
| retaining up to `retain` backup files, including the | |
| original. | |
| :param retain the number of backups (filename.N) to keep. | |
| """ | |
| dirname = os.path.dirname(self.orig) | |
| keepers = [os.path.join(dirname, self.orig)] | |
| for i in range(1, retain + 1): | |
| keepers.append(os.path.join(dirname, f"{self.base}.{i}")) | |
| for i in range(len(keepers) - 2, -1, -1): | |
| if os.path.exists(keepers[i]): | |
| print(f"Copying {keepers[i]} to {keepers[i+1]}", file=sys.stderr) | |
| shutil.copyfile(keepers[i], keepers[i + 1]) | |
| return keepers |
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