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In computer programming, create, read, update, and delete (CRUD) are the four basic operations (actions) of persistent storage. [1] CRUD is also sometimes used to describe user interface conventions that facilitate viewing, searching, and changing information using computer-based forms and reports .
update: Update the files in a working copy with the latest version from a repository; lock: Lock files in a repository from being changed by other users; add: Mark specified files to be added to repository at next commit; remove: Mark specified files to be removed at next commit (note: keeps cohesive revision history of before and at the remove.)
Another precautionary measure is to mark important files as read-only. Many operating systems will warn the user trying to delete such files. Where file-system permissions exist, users who lack the necessary permissions are only able to delete their own files, preventing the erasure of other people's work or critical system files.
File system mazes force the victim to read a directory entry that is not in the OS cache, and the OS puts the victim to sleep while it is reading the directory from disk. Algorithmic complexity attacks force the victim to spend its entire scheduling quantum inside a single system call traversing the kernel's hash table of cached file names.
A lock file is often the best approach if the resource to be controlled is not a regular file at all, so using methods for locking files does not apply. For example, a lock file might govern access to a set of related resources, such as several different files, directories, a group of disk partitions, or selected access to higher level ...
Data remanence is the residual representation of digital data that remains even after attempts have been made to remove or erase the data. This residue may result from data being left intact by a nominal file deletion operation, by reformatting of storage media that does not remove data previously written to the media, or through physical properties of the storage media that allow previously ...
When files with same hashes are found then the file copy is removed and the new file points to the old file. Unlike hard links however, duplicated files are considered to be separate entities and if one of the duplicated files is later modified, then using a system called copy-on-write a copy of that changed file or block is created.
Computers that allow for multiple users implement file permissions to control who may or may not modify, delete, or create files and folders. For example, a given user may be granted only permission to read a file or folder, but not to modify or delete it; or a user may be given permission to read and modify files or folders, but not to execute ...