freedup is a

program Program, programme, programmer, or programming may refer to: Business and management * Program management, the process of managing several related projects * Time management * Program, a part of planning Arts and entertainment Audio * Progra ...

to scan

directories Directory may refer to: * Directory (computing), or folder, a file system structure in which to store computer files * Directory (OpenVMS command) * Directory service, a software application for organizing information about a computer network's u ...

or file lists for duplicate files. The file lists may be provided to an input pipe or internally generated using

find Find, FIND or Finding may refer to: Computing * find (Unix), a command on UNIX platforms * find (Windows), a command on DOS/Windows platforms Books * ''The Find'' (2010), by Kathy Page * ''The Find'' (2014), by William Hope Hodgson Film and t ...

with provided options. There are more options to specify the search conditions more detailed. Other options influence the performed actions, i.e. whether to display only or to specify what kind of link under which circumstances. freedup first compares file sizes, then on equal sizes the MD5 signatures, and before taking actions a byte-by-byte check for verification is performed. An interactive mode allows to decide individually which files to link soft or

hard Hard may refer to: * Hardness, resistance of physical materials to deformation or fracture * Hard water, water with high mineral content Arts and entertainment * ''Hard'' (TV series), a French TV series * Hard (band), a Hungarian hard rock supe ...

or to delete. The comparison by ignoring

metadata Metadata is "data that provides information about other data", but not the content of the data, such as the text of a message or the image itself. There are many distinct types of metadata, including: * Descriptive metadata – the descriptive ...

tags and comments is a unique feature of ''freedup''. Filesize, start and end of unique content is kept for later processing. Comparing

sound file An audio file format is a file format for storing digital audio data on a computer system. The bit layout of the audio data (excluding metadata) is called the audio coding format and can be uncompressed, or audio compression (data), compressed to r ...

s you may ignore the tags, e.g. whether one is tagged with an ID3v1-tag while another sound file with identical music is tagged with

ID3v2 ID3 is a metadata container most often used in conjunction with the MP3 audio file format. It allows information such as the title, artist, album, track number, and other information about the file to be stored in the file itself. There are two ...

. It also works, if you copied and retagged the copy to fit into another album. This works for

JPEG JPEG ( ) is a commonly used method of lossy compression for digital images, particularly for those images produced by digital photography. The degree of compression can be adjusted, allowing a selectable tradeoff between storage size and imag ...

files (

Exif Exchangeable image file format (officially Exif, according to JEIDA/JEITA/CIPA specifications) is a standard that specifies formats for images, sound, and ancillary tags used by digital cameras (including smartphones), scanners and other system ...

) and mp4-Movies as well. An auto-Mode is supported to instruct ''freedup'' to ignore all tags that are recognized. The author will extend this function on demand, if there is sufficient documentation how to strip the tags. freedup is written in

POSIX The Portable Operating System Interface (POSIX) is a family of standards specified by the IEEE Computer Society for maintaining compatibility between operating systems. POSIX defines both the system- and user-level application programming interf ...

compliant C and is released under the

GNU General Public License The GNU General Public License (GNU GPL or simply GPL) is a series of widely used free software licenses that guarantee end users the Four Freedoms (Free software), four freedoms to run, study, share, and modify the software. The license was th ...

. Its complexity is O(n log n) for full file comparison. This is done for equally long files after sorting according to filesize using

qsort qsort is a C standard library function that implements a polymorphic sorting algorithm for arrays of arbitrary objects according to a user-provided comparison function. It is named after the "quicker sort" algorithm (a quicksort variant due to R ...

().

References

External links

Official freedup homepage
freedup freedup freedup freedup freedup freedup freedup freedup freedup freedup freedup freedup {{unix-stub

See also

References

External links