diff options
Diffstat (limited to 'doc/plzip.info')
| -rw-r--r-- | doc/plzip.info | 93 |
1 files changed, 60 insertions, 33 deletions
diff --git a/doc/plzip.info b/doc/plzip.info index a814b3f..cf53f13 100644 --- a/doc/plzip.info +++ b/doc/plzip.info @@ -11,7 +11,7 @@ File: plzip.info, Node: Top, Next: Introduction, Up: (dir) Plzip Manual ************ -This manual is for Plzip (version 1.5, 14 May 2016). +This manual is for Plzip (version 1.6, 12 April 2017). * Menu: @@ -27,7 +27,7 @@ This manual is for Plzip (version 1.5, 14 May 2016). * Concept index:: Index of concepts - Copyright (C) 2009-2016 Antonio Diaz Diaz. + Copyright (C) 2009-2017 Antonio Diaz Diaz. This manual is free documentation: you have unlimited permission to copy, distribute and modify it. @@ -65,11 +65,11 @@ availability: (lziprecover)Data safety. * 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. + lzip manual provides the source 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 the lzip reference implementation is copylefted, which guarantees that it will remain free forever. @@ -117,6 +117,10 @@ two or more compressed files. The result is the concatenation of the corresponding uncompressed files. Integrity testing of concatenated compressed files is also supported. + LANGUAGE NOTE: Uncompressed = not compressed = plain data; it may +never have been compressed. Decompressed is used to refer to data which +have undergone the process of decompression. + File: plzip.info, Node: Invoking plzip, Next: Program design, Prev: Introduction, Up: Top @@ -185,6 +189,21 @@ command line. Keep (don't delete) input files during compression or decompression. +'-l' +'--list' + Print the uncompressed size, compressed size and percentage saved + of the specified file(s). Trailing data are ignored. The values + produced are correct even for multimember files. If more than one + file is given, a final line containing the cumulative sizes is + printed. With '-v', the dictionary size, the number of members in + the file, and the amount of trailing data (if any) are also + printed. With '-vv', the positions and sizes of each member in + multimember files are also printed. '-lq' can be used to verify + quickly (without decompressing) the structural integrity of the + specified files. (Use '--test' to verify the data integrity). + '-alq' additionally verifies that none of the specified files + contain trailing data. + '-m BYTES' '--match-length=BYTES' Set the match length limit in bytes. After a match this long is @@ -236,8 +255,10 @@ command line. 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 file(s). If a file fails the test, plzip may be unable to - check the rest of the files. + the file(s). If a file does not exist, can't be opened, or is a + terminal, plzip continues checking the rest of the files. If a + file fails the test, plzip may be unable to check the rest of the + files. '-v' '--verbose' @@ -420,9 +441,6 @@ following: * For decompression of a regular (seekable) file to another regular file, or for testing of a regular file; the dictionary size. - (Note that regular files with more than 1024 bytes of trailing - data are treated as non-seekable). - * For testing of a non-seekable file or of standard input; the dictionary size plus up to 5 MiB. @@ -474,16 +492,21 @@ File: plzip.info, Node: Trailing data, Next: Examples, Prev: Minimum file siz 7 Extra data appended to the file ********************************* -Sometimes extra data is found appended to a lzip file after the last +Sometimes extra data are found appended to a lzip file after the last member. Such trailing data may be: * Padding added to make the file size a multiple of some block size, - for example when writing to a tape. - - * Garbage added by some not totally successful copy operation. + for example when writing to a tape. It is safe to append any + amount of padding zero bytes to a lzip file. * Useful data added by the user; a cryptographically secure hash, a - description of file contents, etc. + description of file contents, etc. It is safe to append any amount + of text to a lzip file as long as the text does not begin with the + string "LZIP", and does not contain any zero bytes (null + characters). Nonzero bytes and zero bytes can't be safely mixed in + trailing data. + + * Garbage added by some not totally successful copy operation. * Malicious data added to the file in order to make its total size and hash value (for a chosen hash) coincide with those of another @@ -496,8 +519,12 @@ member. Such trailing data may be: the corruption of the integrity information itself. Therefore it can be considered to be below the noise level. + Trailing data are in no way part of the lzip file format, but tools +reading lzip files are expected to behave as correctly and usefully as +possible in the presence of trailing data. + Trailing data can be safely ignored in most cases. In some cases, -like that of user-added data, it is expected to be ignored. In those +like that of user-added data, they are expected to be ignored. In those cases where a file containing trailing data must be rejected, the option '--trailing-error' can be used. *Note --trailing-error::. @@ -545,8 +572,8 @@ Example 5: Compress a whole device in /dev/sdc and send the output to plzip -c /dev/sdc > file.lz -Example 6: The right way of concatenating compressed files. *Note -Trailing data::. +Example 6: The right way of concatenating the decompressed output of two +or more compressed files. *Note Trailing data::. Don't do this cat file1.lz file2.lz file3.lz | plzip -d @@ -607,19 +634,19 @@ Concept index Tag Table: Node: Top221 -Node: Introduction1101 -Node: Invoking plzip5078 -Ref: --trailing-error5647 -Ref: --data-size5890 -Node: Program design11683 -Node: File format13270 -Node: Memory requirements15702 -Node: Minimum file sizes16811 -Node: Trailing data18737 -Node: Examples20121 -Ref: concat-example21286 -Node: Problems21823 -Node: Concept index22349 +Node: Introduction1103 +Node: Invoking plzip5274 +Ref: --trailing-error5843 +Ref: --data-size6086 +Node: Program design12796 +Node: File format14383 +Node: Memory requirements16815 +Node: Minimum file sizes17815 +Node: Trailing data19741 +Node: Examples21648 +Ref: concat-example22813 +Node: Problems23388 +Node: Concept index23914 End Tag Table |