in reply to Flat File Comment

The usual way to control access to files is to set the ownership and permissions on the files and the directories that contain them so that only authorized users are able to access them.

There are database systems with well designed and well tested security and access control capabilities, indexes and constraints - all you need to solve the problems you have described. If security were a concern, I would use proven systems rather than design and build my own.

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Re^2: Flat File Comment
by PilotinControl (Pilgrim) on Dec 10, 2013 at 13:07 UTC

    Hello IG,
    It's not so much a security issue as it is the following: A master file contains all the records, once an item from that master file has been selected it is "copied" to a new "temp" file for use in the program. Once the temp file has out lived its use the items in the master file are able to be selected again. The issue is how do I make the items selected from the master file remain un-selectable until the temp file has been removed? Also the files in use are only a few KB each. Thanks for the ideas and suggestions.

      In that case, rather than editing the master files, I would probably scan the temp file and index its contents, then scan the master file and exclude anything found in the index. If the temp file doesn't exist, then the index will be empty and nothing will be excluded.