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Diffstat (limited to '')
| -rw-r--r-- | doc/plzip.texi (renamed from doc/plzip.texinfo) | 61 |
1 files changed, 36 insertions, 25 deletions
diff --git a/doc/plzip.texinfo b/doc/plzip.texi index 0370677..413a9e3 100644 --- a/doc/plzip.texinfo +++ b/doc/plzip.texi @@ -6,8 +6,8 @@ @finalout @c %**end of header -@set UPDATED 17 September 2013 -@set VERSION 1.1 +@set UPDATED 20 January 2014 +@set VERSION 1.2-pre1 @dircategory Data Compression @direntry @@ -44,7 +44,8 @@ This manual is for Plzip (version @value{VERSION}, @value{UPDATED}). @end menu @sp 1 -Copyright @copyright{} 2009, 2010, 2011, 2012, 2013 Antonio Diaz Diaz. +Copyright @copyright{} 2009, 2010, 2011, 2012, 2013, 2014 +Antonio Diaz Diaz. This manual is free documentation: you have unlimited permission to copy, distribute and modify it. @@ -60,12 +61,9 @@ the one of lzip, bzip2 or gzip. Plzip can compress/decompress large files on multiprocessor machines much faster than lzip, at the cost of a slightly reduced compression -ratio. On files large enough (several GB), plzip can use hundreds of -processors. On files of only a few MB it is better to use lzip. - -Plzip uses the same well-defined exit status values used by lzip and -bzip2, which makes it safer when used in pipes or scripts than -compressors returning ambiguous warning values, like gzip. +ratio. Note that the number of usable threads is limited by file size, +so on files larger than a few GB plzip can use hundreds of processors, +but on files of only a few MB plzip is no faster than lzip. Plzip uses the lzip file format; the files produced by plzip are fully compatible with lzip-1.4 or newer, and can be rescued with lziprecover. @@ -89,12 +87,29 @@ lziprecover program. Lziprecover makes lzip files resistant to bit-flip recovery capabilities, including error-checked merging of damaged copies of a file. -Plzip replaces every file given in the command line with a compressed -version of itself, with the name "original_name.lz". Each compressed -file has the same modification date, permissions, and, when possible, -ownership as the corresponding original, so that these properties can be -correctly restored at decompression time. Plzip is able to read from some -types of non regular files if the @samp{--stdout} option is specified. +Plzip uses the same well-defined exit status values used by lzip and +bzip2, which makes it safer than compressors returning ambiguous warning +values (like gzip) when it is used as a back end for tar or zutils. + +When compressing, plzip replaces every file given in the command line +with a compressed version of itself, with the name "original_name.lz". +When decompressing, plzip attempts to guess the name for the decompressed +file from that of the compressed file as follows: + +@multitable {anyothername} {becomes} {anyothername.out} +@item filename.lz @tab becomes @tab filename +@item filename.tlz @tab becomes @tab filename.tar +@item anyothername @tab becomes @tab anyothername.out +@end multitable + +(De)compressing a file is much like copying or moving it; therefore plzip +preserves the access and modification dates, permissions, and, when +possible, ownership of the file just as "cp -p" does. (If the user ID or +the group ID can't be duplicated, the file permission bits S_ISUID and +S_ISGID are cleared). + +Plzip is able to read from some types of non regular files if the +@samp{--stdout} option is specified. If no file names are specified, plzip compresses (or decompresses) from standard input to standard output. In this case, plzip will decline to @@ -106,15 +121,6 @@ or more compressed files. The result is the concatenation of the corresponding uncompressed files. Integrity testing of concatenated compressed files is also supported. -When decompressing, plzip attempts to guess the name for the decompressed -file from that of the compressed file as follows: - -@multitable {anyothername} {becomes} {anyothername.out} -@item filename.lz @tab becomes @tab filename -@item filename.tlz @tab becomes @tab filename.tar -@item anyothername @tab becomes @tab anyothername.out -@end multitable - WARNING! Even if plzip is bug-free, other causes may result in a corrupt compressed file (bugs in the system libraries, memory errors, etc). Therefore, if the data you are going to compress is important, give the @@ -171,6 +177,7 @@ Print the version number of plzip on the standard output and exit. @item -B @var{bytes} @itemx --data-size=@var{bytes} +@anchor{--data-size} Set the input data block size in bytes. The input file will be divided in chunks of this size before compression is performed. Valid values range from 8 KiB to 1 GiB. Default value is two times the dictionary @@ -212,6 +219,10 @@ as your system can support". If this option is not used, plzip tries to detect the number of processors in the system and use it as default value. @w{@samp{plzip --help}} shows the system's default value. +Note that the number of usable threads is limited to @w{ceil( file_size +/ data_size )} during compression (@pxref{--data-size}), and to the +number of members in the input during decompression. + @item -o @var{file} @itemx --output=@var{file} When reading from standard input and @samp{--stdout} has not been @@ -245,7 +256,7 @@ Use it together with @samp{-v} to see information about the file. @itemx --verbose Verbose mode.@* When compressing, show the compression ratio for each file processed. A -second -v shows the progress of compression.@* +second @samp{-v} shows the progress of compression.@* When decompressing or testing, further -v's (up to 4) increase the verbosity level, showing status, compression ratio, decompressed size, and compressed size. |