Merging upstream version 1.25.
Signed-off-by: Daniel Baumann <daniel@debian.org>
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40 changed files with 207 additions and 245 deletions
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@ -12,7 +12,7 @@ File: lziprecover.info, Node: Top, Next: Introduction, Up: (dir)
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Lziprecover Manual
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******************
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This manual is for Lziprecover (version 1.25-rc1, 18 November 2024).
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This manual is for Lziprecover (version 1.25, 8 January 2025).
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* Menu:
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@ -34,7 +34,7 @@ This manual is for Lziprecover (version 1.25-rc1, 18 November 2024).
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* Concept index:: Index of concepts
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Copyright (C) 2009-2024 Antonio Diaz Diaz.
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Copyright (C) 2009-2025 Antonio Diaz Diaz.
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This manual is free documentation: you have unlimited permission to copy,
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distribute, and modify it.
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@ -69,31 +69,12 @@ the lzip format is extraordinarily safe. The simple and safe design of the
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file format complements the embedded error detection provided by the LZMA
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data stream. Any distance larger than the dictionary size acts as a
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forbidden symbol, allowing the decompressor to detect the approximate
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position of errors, and leaving very little work for the check sequence
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(CRC and data sizes) in the detection of errors. Lzip is usually able to
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detect all possible bit flips in the compressed data without resorting to
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the check sequence. It would be difficult to write an automatic recovery
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tool like lziprecover for the gzip format. And, as far as I know, it has
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never been written.
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The lzip file format is designed for data sharing and long-term
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archiving, taking into account both data integrity and decoder availability:
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* The lzip format provides very safe integrity checking and some data
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recovery means. The program lziprecover can repair bit flip errors
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(one of the most common forms of data corruption) in lzip files, and
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provides data recovery capabilities, including error-checked merging
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of damaged copies of a file. *Note Data safety::.
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* The lzip format is as simple as possible (but not simpler). The lzip
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manual provides the source code of a simple decompressor along with a
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detailed explanation of how it works, so that with the only help of the
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lzip manual it would be possible for a digital archaeologist to extract
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the data from a lzip file long after quantum computers eventually
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render LZMA obsolete.
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* Additionally the lzip reference implementation is copylefted, which
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guarantees that it will remain free forever.
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position of errors, and leaving little work for the check sequence (CRC and
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data sizes) in the detection of errors. Lzip is usually able to detect all
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possible bit flips in the compressed data without resorting to the check
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sequence. It would be difficult to write an automatic recovery tool like
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lziprecover for the gzip format. And, as far as I know, it has never been
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written.
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A nice feature of the lzip format is that a corrupt byte is easier to
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repair the nearer it is from the beginning of the file. Therefore, with the
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@ -111,11 +92,12 @@ able to find and combine the good parts of several damaged copies.
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compressors in the lzip family: lzip, plzip, minilzip/lzlib, clzip, and
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pdlzip.
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If the cause of file corruption is a damaged medium, the combination
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GNU ddrescue + lziprecover is the recommended option for recovering data
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from damaged files. *Note ddrescue-example::, *note ddrescue-example2::, and
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*note ddrescue-example3::, for examples. *Note GNU ddrescue manual:
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(ddrescue)Top, for details about ddrescue.
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GNU ddrescue provides data recovery capabilities which nicely complement
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those of lziprecover. If the cause of file corruption is a damaged medium,
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the combination GNU ddrescue + lziprecover is the recommended option for
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recovering data from damaged files. *Note ddrescue-example::, *note
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ddrescue-example2::, and *note ddrescue-example3::, for examples. *Note GNU
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ddrescue manual: (ddrescue)Top, for details about ddrescue.
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If a file is too damaged for lziprecover to repair it, all the
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recoverable data in all members of the file can be extracted with the
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@ -397,15 +379,15 @@ lziprecover supports the following options: *Note Argument syntax::.
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When creating or reading fec files (but not when listing), for each
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directory operand, read and process all files in that directory,
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recursively. Follow symbolic links given in the command line, but skip
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symbolic links that are encountered recursively. Ignore files with
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extension '.fec', and files and directories named 'fec'.
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symbolic links that are encountered recursively. Ignore files and
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directories named 'fec' or '*[-._]fec'.
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'-R'
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'--dereference-recursive'
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When creating or reading fec files (but not when listing), for each
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directory operand, read and process all files in that directory,
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recursively, following all symbolic links. Ignore files with extension
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'.fec', and files and directories named 'fec'.
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recursively, following all symbolic links. Ignore files and
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directories named 'fec' or '*[-._]fec'.
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'-s'
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'--split'
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@ -691,9 +673,8 @@ POSIX recommends these conventions for command-line arguments.
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* Certain options require an argument.
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* An option and its argument may or may not appear as separate tokens.
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(In other words, the whitespace separating them is optional, unless the
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argument is the empty string). Thus, '-o foo' and '-ofoo' are
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equivalent.
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(In other words, the whitespace separating them is optional). Thus,
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'-o foo' and '-ofoo' are equivalent.
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* One or more options without arguments, followed by at most one option
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that takes an argument, may follow a hyphen in a single token. Thus,
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@ -836,8 +817,8 @@ total device failure is storing backup copies in separate media.
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The extraordinary safety of the lzip format allows lziprecover to use the
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redundance that occurs naturally when making compressed backups. Lziprecover
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can recover data that would not be recoverable from files compressed in
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other formats. Let's see two examples of how much better is lzip compared
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with gzip and bzip2 with respect to data safety:
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other formats. See these two examples of the data recovery capabilities
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offered by lziprecover:
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* Menu:
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@ -1225,7 +1206,7 @@ payload_crc 36 + 4N 4
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'fbs (coded fec_block_size)'
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Number of FEC bytes per block. It is a multiple of 512 bytes between
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512 bytes and 128 TiB.
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512 bytes and 128 TiB. *Note fbs::.
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'prodata_size'
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Size of the protected file. 1 byte to 4 EiB.
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@ -1271,10 +1252,12 @@ payload_crc 12 + fbs 4
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(0xB3, 0x46, 0x45, 0x43).
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'fbn (fec_block_number)'
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Number of this FEC block. Required to compute the decode matrix.
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Number of this FEC block (0 to 32767). Required to compute the decode
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matrix.
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'fbs (coded fec_block_size)'
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*Note fbs::.
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Number of FEC bytes per block. It is a multiple of 512 bytes between
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512 bytes and 128 TiB. *Note fbs::.
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'header_crc'
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CRC32 of the previous fields, including magic.
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@ -2033,43 +2016,43 @@ Concept index
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Tag Table:
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Node: Top226
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Node: Introduction1535
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Node: Invoking lziprecover6387
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Ref: --trailing-error7308
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Ref: --byte-repair8402
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Ref: range-format10483
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Ref: --reproduce10728
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Ref: --unzcrash28455
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Node: Argument syntax33048
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Node: File format35005
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Node: Data safety37759
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Node: Merging with a backup40005
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Node: Reproducing a mailbox41268
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Node: Fec files43722
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Node: How Reed-Solomon works45988
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Node: Implementation details48159
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Node: Creating fec files50224
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Node: Testing with fec files51068
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Node: Repairing with fec files52023
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Ref: ddrescue-example52841
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Node: Fec file format53351
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Ref: fbs56222
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Node: Repairing one byte58011
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Node: Merging files60103
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Ref: performance-of-merge61282
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Ref: ddrescue-example262890
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Node: Reproducing one sector64106
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Ref: performance-of-reproduce68043
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Ref: ddrescue-example370716
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Node: Tarlz73135
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Node: File names76808
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Node: Trailing data77541
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Node: Examples80854
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Ref: concat-example81426
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Node: Unzcrash82825
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Ref: --set-byte87437
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Node: Problems89295
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Node: Concept index89847
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Node: Introduction1529
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Node: Invoking lziprecover5451
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Ref: --trailing-error6372
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Ref: --byte-repair7466
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Ref: range-format9547
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Ref: --reproduce9792
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Ref: --unzcrash27483
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Node: Argument syntax32076
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Node: File format33987
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Node: Data safety36741
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Node: Merging with a backup38960
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Node: Reproducing a mailbox40223
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Node: Fec files42677
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Node: How Reed-Solomon works44943
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Node: Implementation details47114
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Node: Creating fec files49179
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Node: Testing with fec files50023
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Node: Repairing with fec files50978
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Ref: ddrescue-example51796
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Node: Fec file format52306
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Ref: fbs53073
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Node: Repairing one byte57094
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Node: Merging files59186
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Ref: performance-of-merge60365
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Ref: ddrescue-example261973
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Node: Reproducing one sector63189
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Ref: performance-of-reproduce67126
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Ref: ddrescue-example369799
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Node: Tarlz72218
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Node: File names75891
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Node: Trailing data76624
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Node: Examples79937
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Ref: concat-example80509
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Node: Unzcrash81908
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Ref: --set-byte86520
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Node: Problems88378
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Node: Concept index88930
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End Tag Table
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