I've implemented features from your TODO list sections 1 and 2.

[macote]

This update introduces several new features and enhancements based on the initial sections of your TODO.md file:

1. Overall Progress Display:

   • The creation process now clearly shows the current file and a running byte/percentage count.
   • The verification process provides a detailed completion summary including files checked, errors, missing files, and extra files.

2. Statistics Reporting:

   • After create, verify, or update operations, the utility now displays:
     • Total number of files processed.
     • Total bytes processed (human-readable format).
     • Total processing time.
     • Average processing speed (human-readable format).

3. Report Mode:

   • --report-file <PATH>: Allows all output (progress, results, errors) to be logged to a specified file.
   • --silent: Suppresses progress output on the console. When used with --report-file, console output is silenced, but the report file still receives full details.

4. Checksum File Update Feature:

   • --update (or -x): Enables updating an existing checksum file.
     • New files found in the target directory are added to the checksum file.
     • Files with changed sizes (or modification times, implicitly) are re-hashed and their entries updated.
   • --remove-missing: When in update mode, entries in the checksum file for which files are not found on disk are removed from the checksum file.
   • --force-rehash: When in update mode, all files found on disk that are also in the checksum file will be re-hashed, even if their metadata matches.
   • Checksum saving is now atomic (uses a temporary file and rename) to prevent corruption.

These changes significantly enhance the usability and functionality of the hshchk utility.