ChecksumDB

ChecksumDB is a cross-platform (UNIX and Windows) utility for the generation, storage, and comparison of file hashes to guard against corruption. ChecksumDB also uses SQLite for its database, making manual queries easy. Download.

Features

• Files are stored as relative paths, making it easy to scan backup media where files are no longer in their original locations.
• Intelligently detects when files are corrupted and when the user has changed them.
• Flexible database-driven design permits manual querying with SQLite.

Installation

ChecksumDB can be built using GCC with the command line: gcc checksumdb.c -lsqlite3 -lgcrypt -ochecksumdb

On Windows, Cygwin is required as well as Cygwin packages libgcrypt-devel, libgcrypt (libgcrypt11), and libsqlite3-devel. DLL files required are: cygwin1.dll, cygsqlite3-0.dll, cyggcc_s-1.dll, cyggcrypt-11.dll, cyggpg-error-0.dll, cygintl-8.dll, and cygiconv-2.dll.

For Linux and Windows, libraries required for execution are libgcrypt and libsqlite3.

Initial usage

checksumdb -u /home/user/stuff

This will recursively scan all files in /home/user/stuff, compute the SHA256 hash of each file, and store them in /home/user/stuff/checksum.db. /home/user/stuff (the target directory) is a required argument for all operations below.

Scan files & update database

checksumdb -u /home/user/stuff

This will recursively scan all files in /home/user/stuff (working disk to database), compute hashes, and create a new scan record in /home/user/stuff/checksum.db. Additionally, each file will be compared to its existing database records. ChecksumDB follows the following algorithm:

• The file's contents have changed, but the last modified timestamp is after the last ChecksumDB scan: File is recorded as being modified by user.
• The file's contents have changed, and the last modified timestamp is before the last ChecksumDB scan: The file has been corrupted or otherwise not user-modified. Note if you copy over a file with another old file, you may also satisfy this criteria.
• The file cannot be found in the database, but another filename with the same contents was previously recorded: The file is presumed to be a renamed copy of the previous file.
• The file cannot be found in the database, and no files with the same contents have been previously recorded: The file is added as a new file.

In the second case, a warning is always printed to inform the user about the potentially corrupted file. -v or -vv modes (verbosity and extra verbosity, respectively) will print informational messages about the other cases as well.

Scan without updating

checksumdb -s /home/user/stuff

In scan mode, the database is opened in read-only mode. This is designed for checking the integrity of backups or other files not in active use. This method works from the database to the disk, checking that every file in the database exists on the disk with a matching hash.

Typical Usage

Typical usage is -u when files are in use on a computer, and then -s on backups. The intent is to periodically (e.g. monthly) run -u on a production system, with -s being used to verify backup mediums as needed.

View past scan records

checksumdb -e /home/user/stuff

Lists past scans: scan number, scan date and time, and the directory scanned.

View file history

checksumdb -h /home/user/stuff/file1.txt /home/user/stuff

Lists the file history for /home/user/stuff/file1.txt: The scans in which it was found, its size, the status of each scan, scan dates, and the history of last modified dates. For events, the following statuses are possible:

• NEW - The file was found for the first time and added to the database.
• USER MOD - The file changed since the last scan, but so did the last modified date, and the user is presumed to have changed it.
• CHANGED - The file changed since the last scan and the last modified date is older than the last scan, so the file may have changed without user intervention.
• RENAMED - The file was found in a previous scan with the same contents, but under a different name. It is presumed that the previous file was renamed to this file.
• OK - No change in the file since the last scan.

Optional arguments

checksumdb -f /home/user/stuffdatabase.db -u /home/user/stuff

-f specifies a filename for the database. By default, the database is a file named checksum.db in the top level of the target directory specified. With -f, you can place the database elsewhere, including outside of the target directory entirely.

checksumdb -k 5 -u /home/stuff

-k nn prevents the database from growing too large after repeated scans by only retaining the last nn scans (including the current one). Must be used with -u.

checksumdb -# 34 -s /home/stuff

-# nn uses scan number nn when comparing the database against the files. The default is to use the most recent scan. A list of past scans can be obtained with -e (see above) and -# used to compare against an older scan.

checksumdb -v -u /home/stuff

-v (and -vv) are verbosity options to show additional information. -v will show output for all files, and -vv will show greater output, including actual hash values. If you are paranoid about file integrity, -v is a nice switch.