Data compression archiver and format
dar (diskarchive) is acomputer program, a command-line archiving and backup tool[4] intended as a replacement or alternative totar inUnix-likeoperating systems.[citation needed]
The feature set of Dar is vast: it encompass the care taken to involve many if not all attributes and properties of files under backup, to the way this data is wrapped with selective compression, encryption, slicing associated to a very rich set of filtering mechanism (based on filename, pathname, Extended Attribute presence, filesystem location, and so forth) to select the data under the operation, where theoperation is one of the following: backup, restoration, content listing, archive testing, backup isolation (copying the table of content into a separated file for redundancy and easier differential backup), merging and repairing. Here follows a more detailed list of features:
- Support for slices, archives split over multiple files of a particular size
- Option of deleting files from the system which are removed in the archive
- Full backup
- Differential backup
- Incremental backup,
- Decremental backup (schema where the most recent is a full backup and the older are difference from a more recent one)
- Takes care of any type ofinode (directory, plain files,symlinks,special devices,named pipes,sockets,doors, ...)
- Takes care ofhard-linked inodes (hard-linked plain files,char devices,block devices, hard-linked symlinks)
- Takes care ofsparse files
- Takes care of Linux fileExtended Attributes,
- Takes care of Linux fileACL
- Takes care of Mac OS Xfile forks
- Takes care of some filesystem specific attributes like Birthdate ofHFS+ filesystem and immutable,data-journaling,secure-deletion,no-tail-merging, undeletable, noatime attributes of ext2/3/4 filesystem.
- Per-file compression withgzip,bzip2,lzo,xz,lzma,zstd orlz4 (as opposed to compressing the whole archive). The user can choose not to compress already compressed files based on their filename suffix (a default rich list of such suffix is provided with dar)
- Fast-extracting of files from anywhere in the archive
- Fast listing of archive contents through saving the catalogue of files in the archive
- OptionalBlowfish,Twofish,AES,Serpent,Camellia encryption, including a tunableKey Derivation Function (using
- argon2 by default) withsalt and an encryptedelastic buffer at the beginning and the end of the data to reduce the risk ofcodebook attack
- Optional public key encryption and signature (OpenPGP)
- Live filesystem backup: detects when a file has been modified while it was read for backup and can retry saving it up to a given maximum number of retries
- Hash file (MD5,SHA1,SHA-512 orwhirlpool) generated on-fly for each slice, the resulting file is compatible with
md5sum -c,sha1sum -c,sha512sum -c orwhirlpool-hash -c, to be able to quickly check each slice's integrity - Filesystem independent: it may be used to restore a system to a partition of a different size and/or to a partition with a different filesystem[5]
- Backup can be stored locally but also remotely and efficiently viaFTP orSFTP without local storage requirement and within a backup only the needed portions of data are requested over the network (decompression and deciphering is done after transfer when the data comes to dar).
There are GUI frontends for dar called:
- Kdar for Linux, specificallyKDE,
- DarGUI for Linux and Windows,
- gdar for Linux.
- Webdar web-based GUI with all dar features (including FTP and SFTP remote backups)
A text-mode browser/extractor: plugin for dar files in mc (Midnight Commander).
A scheduler / command-line frontend known as SaraB allows theTowers of Hanoi,Grandfather-Father-Son, or any custombackup rotation strategy, and modifications are available forPAR file support. Extended versions known as bzSaraB and baras are also available.