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diff --git a/doc/lziprecover.info b/doc/lziprecover.info index 5f8ad08..1248e6f 100644 --- a/doc/lziprecover.info +++ b/doc/lziprecover.info @@ -1,5 +1,5 @@ -This is lziprecover.info, produced by makeinfo version 4.13 from -lziprecover.texinfo. +This is lziprecover.info, produced by makeinfo version 4.13+ from +lziprecover.texi. INFO-DIR-SECTION Data Compression START-INFO-DIR-ENTRY @@ -12,7 +12,7 @@ File: lziprecover.info, Node: Top, Next: Introduction, Up: (dir) Lziprecover Manual ****************** -This manual is for Lziprecover (version 1.15, 14 September 2013). +This manual is for Lziprecover (version 1.16-pre1, 5 April 2014). * Menu: @@ -27,7 +27,7 @@ This manual is for Lziprecover (version 1.15, 14 September 2013). * Concept index:: Index of concepts - Copyright (C) 2009, 2010, 2011, 2012, 2013 Antonio Diaz Diaz. + Copyright (C) 2009, 2010, 2011, 2012, 2013, 2014 Antonio Diaz Diaz. This manual is free documentation: you have unlimited permission to copy, distribute and modify it. @@ -43,18 +43,29 @@ lzip compressed data format (.lz), able to repair slightly damaged files, recover badly damaged files from two or more copies, extract data from damaged files, decompress files and test integrity of files. - The lzip file format is designed for long-term data archiving. It is -clean, provides very safe 4 factor integrity checking, and is backed by -the recovery capabilities of lziprecover. + The lzip file format is designed for long-term data archiving, taking +into account both data integrity and decoder availability: + + * The lzip format provides very safe integrity checking and some data + recovery means. The lziprecover program can repair bit-flip errors + (one of the most common forms of data corruption) in lzip files, + and provides data recovery capabilities, including error-checked + merging of damaged copies of a file. + + * The lzip format is as simple as possible (but not simpler). The + lzip manual provides the code of a simple decompressor along with + a detailed explanation of how it works, so that with the only help + of the lzip manual it would be possible for a digital + archaeologist to extract the data from a lzip file long after + quantum computers eventually render LZMA obsolete. + + * Additionally lzip is copylefted, which guarantees that it will + remain free forever. Lziprecover is able to recover or decompress files produced by any of the compressors in the lzip family; lzip, plzip, minilzip/lzlib, clzip and pdlzip. - Lziprecover makes lzip files resistant to bit-flip (one of the most -common forms of data corruption), and can safely merge multiple damaged -backup copies. - If the cause of file corruption is damaged media, the combination GNU ddrescue + lziprecover is the best option for recovering data from multiple damaged copies. *Note ddrescue-example::, for an example. @@ -96,113 +107,113 @@ The format for running lziprecover is: Lziprecover supports the following options: -`-h' -`--help' +'-h' +'--help' Print an informative help message describing the options and exit. -`-V' -`--version' +'-V' +'--version' Print the version number of lziprecover on the standard output and exit. -`-c' -`--stdout' +'-c' +'--stdout' Decompress to standard output. Needed when reading from a named pipe (fifo) or from a device. Use it to recover as much of the uncompressed data as possible when decompressing a corrupt file. -`-d' -`--decompress' +'-d' +'--decompress' Decompress. -`-D RANGE' -`--range-decompress=RANGE' +'-D RANGE' +'--range-decompress=RANGE' Decompress only a range of bytes starting at decompressed byte - position `BEGIN' and up to byte position `END - 1'. Three formats - of RANGE are recognized, `BEGIN', `BEGIN-END', and `BEGIN,SIZE'. + position 'BEGIN' and up to byte position 'END - 1'. Three formats + of RANGE are recognized, 'BEGIN', 'BEGIN-END', and 'BEGIN,SIZE'. If only BEGIN is specified, END is taken as the end of the file. The produced bytes are sent to standard output unless the - `--output' option is used. In order to guarantee the correctness + '--output' option is used. In order to guarantee the correctness of the data produced, all members containing any part of the desired data are decompressed and their integrity is verified. This operation is more efficient in multi-member files because it only decompresses the members containing the desired data. -`-f' -`--force' +'-f' +'--force' Force overwrite of output files. -`-i' -`--ignore-errors' - Make `--range-decompress' ignore data errors and continue +'-i' +'--ignore-errors' + Make '--range-decompress' ignore data errors and continue decompressing the remaining members in the file. For example, - `lziprecover -i -D0 file.lz > file' decompresses all the - recoverable data in all members of `file.lz' without having to + 'lziprecover -i -D0 file.lz > file' decompresses all the + recoverable data in all members of 'file.lz' without having to split it first. -`-k' -`--keep' +'-k' +'--keep' Keep (don't delete) input files during decompression. -`-l' -`--list' +'-l' +'--list' Print total file sizes and ratios. The values produced are correct - even for multi-member files. Use it together with `-v' to see + even for multi-member files. Use it together with '-v' to see information about the members in the file. -`-m' -`--merge' +'-m' +'--merge' Try to produce a correct file merging the good parts of two or more damaged copies. If successful, a repaired copy is written to the - file `FILE_fixed.lz'. The exit status is 0 if a correct file could - be produced, 2 otherwise. See the chapter `Merging files' (*note + file 'FILE_fixed.lz'. The exit status is 0 if a correct file could + be produced, 2 otherwise. See the chapter 'Merging files' (*note Merging files::) for a complete description of the merge mode. -`-o FILE' -`--output=FILE' - Place the output into `FILE' instead of into `FILE_fixed.lz'. If +'-o FILE' +'--output=FILE' + Place the output into 'FILE' instead of into 'FILE_fixed.lz'. If splitting, the names of the files produced are in the form - `rec01FILE', `rec02FILE', etc. If decompressing from standard - input and `--stdout' has not been specified, use `FILE' as the + 'rec01FILE', 'rec02FILE', etc. If decompressing from standard + input and '--stdout' has not been specified, use 'FILE' as the name of the decompressed file. -`-q' -`--quiet' +'-q' +'--quiet' Quiet operation. Suppress all messages. -`-R' -`--repair' +'-R' +'--repair' Try to repair a file with small errors (up to one byte error per member). If successful, a repaired copy is written to the file - `FILE_fixed.lz'. `FILE' is not modified at all. The exit status + 'FILE_fixed.lz'. 'FILE' is not modified at all. The exit status is 0 if the file could be repaired, 2 otherwise. See the chapter - `Repairing files' (*note Repairing files::) for a complete + 'Repairing files' (*note Repairing files::) for a complete description of the repair mode. -`-s' -`--split' - Search for members in `FILE' and write each member in its own - `.lz' file. You can then use `lziprecover -t' to test the +'-s' +'--split' + Search for members in 'FILE' and write each member in its own + '.lz' file. You can then use 'lziprecover -t' to test the integrity of the resulting files, decompress those which are undamaged, and try to repair or partially decompress those which are damaged. - The names of the files produced are in the form `rec01FILE.lz', - `rec02FILE.lz', etc, and are designed so that the use of wildcards + The names of the files produced are in the form 'rec01FILE.lz', + 'rec02FILE.lz', etc, and are designed so that the use of wildcards in subsequent processing, for example, - `lziprecover -cd rec*FILE.lz > recovered_data', processes the + 'lziprecover -cd rec*FILE.lz > recovered_data', processes the files in the correct order. The number of digits used in the names - varies depending on the number of members in `FILE'. + varies depending on the number of members in 'FILE'. -`-t' -`--test' +'-t' +'--test' Check integrity of the specified file(s), but don't decompress them. This really performs a trial decompression and throws away - the result. Use it together with `-v' to see information about + the result. Use it together with '-v' to see information about the file. -`-v' -`--verbose' +'-v' +'--verbose' Verbose mode. When decompressing or testing, further -v's (up to 4) increase the verbosity level, showing status, compression ratio, dictionary @@ -211,7 +222,7 @@ The format for running lziprecover is: Numbers given as arguments to options may be followed by a multiplier -and an optional `B' for "byte". +and an optional 'B' for "byte". Table of SI and binary prefixes (unit multipliers): @@ -239,7 +250,7 @@ File: lziprecover.info, Node: Repairing files, Next: Merging files, Prev: Inv Lziprecover is able to repair files with small errors (up to one byte error per member). The error may be located anywhere in the file except -in the header (first 6 bytes of each member) or in the `Member size' +in the header (first 6 bytes of each member) or in the 'Member size' field of the trailer (last 8 bytes of each member). This makes lzip files resistant to bit-flip, one of the most common forms of data corruption. @@ -323,15 +334,15 @@ additional information before, between, or after them. All multibyte values are stored in little endian order. -`ID string' +'ID string' A four byte string, identifying the lzip format, with the value "LZIP" (0x4C, 0x5A, 0x49, 0x50). -`VN (version number, 1 byte)' +'VN (version number, 1 byte)' Just in case something needs to be modified in the future. 1 for now. -`DS (coded dictionary size, 1 byte)' +'DS (coded dictionary size, 1 byte)' Lzip divides the distance between any two powers of 2 into 8 equally spaced intervals, named "wedges". The dictionary size is calculated by taking a power of 2 (the base size) and substracting @@ -343,18 +354,18 @@ additional information before, between, or after them. Example: 0xD3 = 2^19 - 6 * 2^15 = 512 KiB - 6 * 32 KiB = 320 KiB Valid values for dictionary size range from 4 KiB to 512 MiB. -`Lzma stream' +'Lzma stream' The lzma stream, finished by an end of stream marker. Uses default values for encoder properties. See the lzip manual for a full description. -`CRC32 (4 bytes)' +'CRC32 (4 bytes)' CRC of the uncompressed original data. -`Data size (8 bytes)' +'Data size (8 bytes)' Size of the uncompressed original data. -`Member size (8 bytes)' +'Member size (8 bytes)' Total size of the member, including header and trailer. This field acts as a distributed index, allows the verification of stream integrity, and facilitates safe recovery of undamaged members from @@ -368,30 +379,30 @@ File: lziprecover.info, Node: Examples, Next: Unzcrash, Prev: File format, U ******************************** Example 1: Restore a regular file from its compressed version -`file.lz'. If the operation is successful, `file.lz' is removed. +'file.lz'. If the operation is successful, 'file.lz' is removed. lziprecover -d file.lz -Example 2: Verify the integrity of the compressed file `file.lz' and +Example 2: Verify the integrity of the compressed file 'file.lz' and show status. lziprecover -tv file.lz -Example 3: Decompress `file.lz' partially until 10 KiB of decompressed +Example 3: Decompress 'file.lz' partially until 10 KiB of decompressed data are produced. lziprecover -D 0,10KiB file.lz -Example 4: Decompress `file.lz' partially from decompressed byte 10000 +Example 4: Decompress 'file.lz' partially from decompressed byte 10000 to decompressed byte 15000 (5000 bytes are produced). lziprecover -D 10000-15000 file.lz -Example 5: Repair small errors in the file `file.lz'. (Indented lines +Example 5: Repair small errors in the file 'file.lz'. (Indented lines are abridged diagnostic messages from lziprecover). lziprecover -v -R file.lz @@ -399,8 +410,8 @@ are abridged diagnostic messages from lziprecover). mv file_fixed.lz file.lz -Example 6: Split the multi-member file `file.lz' and write each member -in its own `recXXXfile.lz' file. Then use `lziprecover -t' to test the +Example 6: Split the multi-member file 'file.lz' and write each member +in its own 'recXXXfile.lz' file. Then use 'lziprecover -t' to test the integrity of the resulting files. lziprecover -s file.lz @@ -424,10 +435,10 @@ error-checked merging of copies (*Note GNU ddrescue manual: Example 8: Recover the first volume of those created with the command -`lzip -b 32MiB -S 650MB big_db' from two copies, `big_db1_00001.lz' and -`big_db2_00001.lz', with member 07 damaged in the first copy, member 18 +'lzip -b 32MiB -S 650MB big_db' from two copies, 'big_db1_00001.lz' and +'big_db2_00001.lz', with member 07 damaged in the first copy, member 18 damaged in the second copy, and member 12 damaged in both copies. The -correct file produced is saved in `big_db_00001.lz'. +correct file produced is saved in 'big_db_00001.lz'. lziprecover -m -v -o big_db_00001.lz big_db1_00001.lz big_db2_00001.lz Input files merged successfully @@ -440,7 +451,7 @@ File: lziprecover.info, Node: Unzcrash, Next: Problems, Prev: Examples, Up: The lziprecover package also includes unzcrash, a program written to test robustness to decompression of corrupted data, inspired by -unzcrash.c from Julian Seward's bzip2. Type `make unzcrash' in the +unzcrash.c from Julian Seward's bzip2. Type 'make unzcrash' in the lziprecover source directory to build it. Unzcrash reads the specified file and then repeatedly decompresses @@ -461,40 +472,40 @@ programs with a suitable command line syntax. Unzcrash supports the following options: -`-h' -`--help' +'-h' +'--help' Print an informative help message describing the options and exit. -`-V' -`--version' +'-V' +'--version' Print the version number of unzcrash on the standard output and exit. -`-b RANGE' -`--bits=RANGE' +'-b RANGE' +'--bits=RANGE' Test N-bit errors only, instead of testing all the 255 wrong - values for each byte. `N-bit error' means any value differing from + values for each byte. 'N-bit error' means any value differing from the original value in N bit positions, not a value differing from the original value in the bit position N. The number of N-bit errors per byte (N = 1 to 8) is: 8 28 56 70 56 28 8 1 Examples of RANGE: 1 1,2,3 1-4 1,3-5,8 1-3,5-8 -`-p BYTES' -`--position=BYTES' +'-p BYTES' +'--position=BYTES' First byte position to test in the file. Defaults to 0. -`-q' -`--quiet' +'-q' +'--quiet' Quiet operation. Suppress all messages. -`-s BYTES' -`--size=BYTES' +'-s BYTES' +'--size=BYTES' Number of byte positions to test. If not specified, the whole file is tested. -`-v' -`--verbose' +'-v' +'--verbose' Verbose mode. @@ -516,7 +527,7 @@ for all eternity, if not longer. If you find a bug in lziprecover, please send electronic mail to <lzip-bug@nongnu.org>. Include the version number, which you can find -by running `lziprecover --version'. +by running 'lziprecover --version'. File: lziprecover.info, Node: Concept index, Prev: Problems, Up: Top @@ -540,17 +551,17 @@ Concept index Tag Table: -Node: Top228 -Node: Introduction1096 -Node: Invoking lziprecover3249 -Node: Repairing files8687 -Node: Merging files9406 -Node: File format11177 -Node: Examples13687 -Ref: ddrescue-example14888 -Node: Unzcrash15997 -Node: Problems18369 -Node: Concept index18919 +Node: Top226 +Node: Introduction1100 +Node: Invoking lziprecover3858 +Node: Repairing files9296 +Node: Merging files10015 +Node: File format11786 +Node: Examples14296 +Ref: ddrescue-example15497 +Node: Unzcrash16606 +Node: Problems18978 +Node: Concept index19528 End Tag Table |