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//$Header$ |
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//{211fc600-db2e-4703-bf40-968a2f063b13} |
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//------------------------------------------------------------------------------------------------- |
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//Copyright (c) 2018, David T. Ashley |
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// |
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//This file is part of "ets_dedup", a program for eliminating duplicate files in a subdirectory |
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//tree. |
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// |
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//This source code and any program in which it is compiled/used is licensed under the MIT License, |
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//reproduced below. |
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// |
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//Permission is hereby granted, free of charge, to any person obtaining a copy of |
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//this software and associated documentation files(the "Software"), to deal in the |
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//Software without restriction, including without limitation the rights to use, |
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//copy, modify, merge, publish, distribute, sublicense, and / or sell copies of the |
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//Software, and to permit persons to whom the Software is furnished to do so, |
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//subject to the following conditions : |
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// |
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//The above copyright notice and this permission notice shall be included in all |
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//copies or substantial portions of the Software. |
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// |
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//THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
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//IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
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//FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
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//AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
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//LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
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//OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE |
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//SOFTWARE. |
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//------------------------------------------------------------------------------------------------- |
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#include <stdio.h> |
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|
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const char *ets_dedup_description[] = |
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{ |
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"ets_dedup (mnemonic: DE-DUPlicate) is a program for identifying and", |
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"eliminating duplicate files (by any name) at any depth in a subdirectory and" |
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"its children. The most common application for the program would be the", |
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"reduction of personal clutter, i.e. duplicate photos and downloads.", |
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}; |
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|
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const char *ets_dedup_instructions[] = |
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{ |
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"Usage", |
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"-----" |
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"ets_dedup [-option_1 [ ... [-option_n]]] [--] [pref_dir_1 [ ... [pref_dir_n]]]" |
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" If no options are provided, emits full documentation to stdout. If options", |
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" are provided, analyzes and optionally deletes duplicate files in the", |
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" current working directory and all its children. With large sets of files", |
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" This program can take a long time to run (hours), because it calculates", |
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" the SHA512 digest of every file." |
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"", |
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" ets_dedup is a dangerous program in that it can destroy information (which", |
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" file is in which directory is information, and it is possible to destroy", |
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" information without deleting the last of a set of duplicate files).", |
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" However, ets_dedup is safe in the sense that it will never delete the last", |
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" of a set of identical files (this cannot be done using this program,", |
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" automatically or manually)." |
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"", |
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"Options", |
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"-------", |
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"-report", |
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" Analyzes the current working directory and all its children for duplicates,", |
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" and writes a full report to the console. The report includes which files", |
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" are duplicates, and approximately how much storage space would be saved by", |
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" eliminating all duplicates and by eliminating duplicates of individual", |
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" files and of subdirectories. The report is voluminous and is typically", |
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" redirected to a file.", |
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"-dedup_full_auto", |
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" Deletes all duplicate files, leaving only one copy (by any name or", |
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" extension) of any file. If duplicates are in the same directory, the", |
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" first one in alphabetical order is retained. If duplicates are in different", |
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" directories, a non-deterministic algorithm is used that tends to leave", |
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" larger directories intact while consuming smaller directories.", |
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"-dedup_auto_dir_pri", |
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" Deletes all duplicate files, leaving only one copy (by any name or", |
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" extension). However, in the selection of which duplicates to delete, the", |
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" copy in pref_dir_1 is given preference to remain over the copy in", |
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" pref_dir_2, ..., over the copy in pref_dir_n, and finally over files in", |
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" subdirectories not covered by any of the specified directories. If", |
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" multiple copies of a file exist in the highest-priority preferred directory", |
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" specified, they are all retained. If there are duplicates that exist only", |
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" outside the set of specified preferred directories, none are deleted." |
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"-dedup_auto_dir_equal", |
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" The specified directories are given priority over all directories not", |
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" specified (this creates two equivalence classes--the directories specified", |
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" and the directories not specified). Duplicates that exist both in at least", |
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" one of the specified directories and outside the set of specified", |
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" directories have the outside copies deleted. No files within the set of", |
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" specified directories are deleted. If a file has copies only outside, no", |
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" copies are deleted.", |
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"-dedup_manual_interactive", |
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" Performs a full analysis, then allows interactive manual operations. The", |
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" operations involve descending into and ascending out of directories, and", |
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" setting a given directory or file as authoritative (meaning all external", |
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" copies will be deleted) or non-authoritative (meaning that duplicates", |
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" within the non-authoritative object are not retained).", |
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"-dry_run", |
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" Provides all information about what would have been deleted, but deletes no", |
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" files. This option can be useful for ensuring that the behavior of the", |
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" program will be acceptable.", |
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"", |
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"Limitations", |
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"-----------", |
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" ( 1) Unicode in path names supplied on the command line and in file and", |
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" directory names is not supported.", |
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" ( 2) Unicode in file and directory names may or may not be supported.", |
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" This depends on technical details of Linux/Unix and Windows that", |
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" are tool voluminous to include here.", |
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" ( 3) The program rebuilds its internal data structures each time it is", |
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" run (which involves calculating the SHA512 digest of every file in", |
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" the current working directory and its children). This is a very", |
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" time-consuming operation. The program does not save any information", |
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" between invocations." |
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" ( 4) The program builds all data structures in memory, and so is limited" |
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" by the amount of usable memory in the computer system. A reasonable", |
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" estimate of memory consumption might be 250 bytes per file to be", |
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" analyzed (100 bytes for the path name, 128 bytes for the SHA512", |
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" digest, and 22 bytes for other overhead). Assuming 1GB of usable", |
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" memory, this gives an upper limit of around 4 million files.", |
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" This suggests that the program would be usable for most de-duplication", |
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" tasks.", |
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" ( 5) The program does not provide information about near duplicates.", |
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" The program processes files only in terms of same or different.", |
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"", |
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"Technical Notes", |
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"---------------", |
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" ( 1) Although the probability of two files with different contents having", |
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" the same SHA512 digest is astronomically small (a hash collision with", |
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" SHA512 has never been found), the program handles this case by", |
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" comparing each file to be deleted with another file with the same", |
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" SHA512 hash before deletion. If the file contents are identical (the", |
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" expected case) the deletion will occur. However, if the file contents", |
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" are not identical (a case which will probably never occur), the", |
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" deletion is not performed. This prevents the program from EVER", |
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" removing a unique file.", |
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}; |
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|
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|
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int c_main(int argc, char **argv) |
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{ |
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printf("Execution begins.\n"); |
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printf("Execution ends.\n"); |
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return 0; |
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} |
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