Backup file (.3kc)

Pro/3 automatically backs up the KB file  xxx.3kb to xxx.3kc each time the KB is opened if backup functionality is activated (ref. Processing Preferences window - the backup preferences is stored in the pro3.ini file). The .3kc backup file is copied back to the .3kb file if you regret the changes you eventually made to the database during a session. The backup file will also be copied back to the .3kb file if Pro/3, upon opening the KB, discovers that the .3kb file is unusable (corrupted or improperly closed). The KE will be prompted to confirm before .3kc is copied back to the .3kb file.

Notes:

• To avoid unnecessary copying, the copying from xxx.3kb to xxx.3kc will be done only if xxx.3kc is flagged as different from xxx.3kb. The xxx.3eq semaphore file (under) is used for this purpose such that the files are considered identical if the semaphore-file xxx.3eq is present. (Pro/3 administers the creation and deletion of this file).
• Separate backup-files will be maintained for each external database (if any).

Refer to Knowledge Source Backup/Restore.

Semaphore files

Pro/3 uses one or two metaphor (flag files) to track two states relating to a database. The presence of the file xxx.3eq signifies that the corresponding database's backup file (xxx.3kc) is up-to-date (identical to the database file). Absence of this semaphore file signifies that the database backup file is old or non-existing. The presence of the file xxx.3op signifies that the corresponding database is either open, or if not open, not properly closed. Pro/3 will in a subsequent database opening-attempt suggest that the KE uses the backup file (xxx.3kc), i.e. because the database apparantly was improperly closed. This will of course be attempted only if a database backup file actually exists.