diff options
Diffstat (limited to '')
| -rw-r--r-- | bzip2.1.preformatted | 226 |
1 files changed, 81 insertions, 145 deletions
diff --git a/bzip2.1.preformatted b/bzip2.1.preformatted index 9f18339..0f20cb5 100644 --- a/bzip2.1.preformatted +++ b/bzip2.1.preformatted | |||
| @@ -1,11 +1,9 @@ | |||
| 1 | |||
| 2 | |||
| 3 | |||
| 4 | bzip2(1) bzip2(1) | 1 | bzip2(1) bzip2(1) |
| 5 | 2 | ||
| 6 | 3 | ||
| 4 | |||
| 7 | NNAAMMEE | 5 | NNAAMMEE |
| 8 | bzip2, bunzip2 - a block-sorting file compressor, v1.0 | 6 | bzip2, bunzip2 - a block-sorting file compressor, v1.0.2 |
| 9 | bzcat - decompresses files to stdout | 7 | bzcat - decompresses files to stdout |
| 10 | bzip2recover - recovers data from damaged bzip2 files | 8 | bzip2recover - recovers data from damaged bzip2 files |
| 11 | 9 | ||
| @@ -22,20 +20,20 @@ DDEESSCCRRIIPPTTIIOONN | |||
| 22 | sorting text compression algorithm, and Huffman coding. | 20 | sorting text compression algorithm, and Huffman coding. |
| 23 | Compression is generally considerably better than that | 21 | Compression is generally considerably better than that |
| 24 | achieved by more conventional LZ77/LZ78-based compressors, | 22 | achieved by more conventional LZ77/LZ78-based compressors, |
| 25 | and approaches the performance of the PPM family of sta- | 23 | and approaches the performance of the PPM family of sta |
| 26 | tistical compressors. | 24 | tistical compressors. |
| 27 | 25 | ||
| 28 | The command-line options are deliberately very similar to | 26 | The command-line options are deliberately very similar to |
| 29 | those of _G_N_U _g_z_i_p_, but they are not identical. | 27 | those of _G_N_U _g_z_i_p_, but they are not identical. |
| 30 | 28 | ||
| 31 | _b_z_i_p_2 expects a list of file names to accompany the com- | 29 | _b_z_i_p_2 expects a list of file names to accompany the com |
| 32 | mand-line flags. Each file is replaced by a compressed | 30 | mand-line flags. Each file is replaced by a compressed |
| 33 | version of itself, with the name "original_name.bz2". | 31 | version of itself, with the name "original_name.bz2". |
| 34 | Each compressed file has the same modification date, per- | 32 | Each compressed file has the same modification date, per |
| 35 | missions, and, when possible, ownership as the correspond- | 33 | missions, and, when possible, ownership as the correspond |
| 36 | ing original, so that these properties can be correctly | 34 | ing original, so that these properties can be correctly |
| 37 | restored at decompression time. File name handling is | 35 | restored at decompression time. File name handling is |
| 38 | naive in the sense that there is no mechanism for preserv- | 36 | naive in the sense that there is no mechanism for preserv |
| 39 | ing original file names, permissions, ownerships or dates | 37 | ing original file names, permissions, ownerships or dates |
| 40 | in filesystems which lack these concepts, or have serious | 38 | in filesystems which lack these concepts, or have serious |
| 41 | file name length restrictions, such as MS-DOS. | 39 | file name length restrictions, such as MS-DOS. |
| @@ -58,18 +56,6 @@ DDEESSCCRRIIPPTTIIOONN | |||
| 58 | filename.bz2 becomes filename | 56 | filename.bz2 becomes filename |
| 59 | filename.bz becomes filename | 57 | filename.bz becomes filename |
| 60 | filename.tbz2 becomes filename.tar | 58 | filename.tbz2 becomes filename.tar |
| 61 | |||
| 62 | |||
| 63 | |||
| 64 | 1 | ||
| 65 | |||
| 66 | |||
| 67 | |||
| 68 | |||
| 69 | |||
| 70 | bzip2(1) bzip2(1) | ||
| 71 | |||
| 72 | |||
| 73 | filename.tbz becomes filename.tar | 59 | filename.tbz becomes filename.tar |
| 74 | anyothername becomes anyothername.out | 60 | anyothername becomes anyothername.out |
| 75 | 61 | ||
| @@ -78,23 +64,23 @@ bzip2(1) bzip2(1) | |||
| 78 | guess the name of the original file, and uses the original | 64 | guess the name of the original file, and uses the original |
| 79 | name with _._o_u_t appended. | 65 | name with _._o_u_t appended. |
| 80 | 66 | ||
| 81 | As with compression, supplying no filenames causes decom- | 67 | As with compression, supplying no filenames causes decom |
| 82 | pression from standard input to standard output. | 68 | pression from standard input to standard output. |
| 83 | 69 | ||
| 84 | _b_u_n_z_i_p_2 will correctly decompress a file which is the con- | 70 | _b_u_n_z_i_p_2 will correctly decompress a file which is the con |
| 85 | catenation of two or more compressed files. The result is | 71 | catenation of two or more compressed files. The result is |
| 86 | the concatenation of the corresponding uncompressed files. | 72 | the concatenation of the corresponding uncompressed files. |
| 87 | Integrity testing (-t) of concatenated compressed files is | 73 | Integrity testing (-t) of concatenated compressed files is |
| 88 | also supported. | 74 | also supported. |
| 89 | 75 | ||
| 90 | You can also compress or decompress files to the standard | 76 | You can also compress or decompress files to the standard |
| 91 | output by giving the -c flag. Multiple files may be com- | 77 | output by giving the -c flag. Multiple files may be com |
| 92 | pressed and decompressed like this. The resulting outputs | 78 | pressed and decompressed like this. The resulting outputs |
| 93 | are fed sequentially to stdout. Compression of multiple | 79 | are fed sequentially to stdout. Compression of multiple |
| 94 | files in this manner generates a stream containing multi- | 80 | files in this manner generates a stream containing multi |
| 95 | ple compressed file representations. Such a stream can be | 81 | ple compressed file representations. Such a stream can be |
| 96 | decompressed correctly only by _b_z_i_p_2 version 0.9.0 or | 82 | decompressed correctly only by _b_z_i_p_2 version 0.9.0 or |
| 97 | later. Earlier versions of _b_z_i_p_2 will stop after decom- | 83 | later. Earlier versions of _b_z_i_p_2 will stop after decom |
| 98 | pressing the first file in the stream. | 84 | pressing the first file in the stream. |
| 99 | 85 | ||
| 100 | _b_z_c_a_t (or _b_z_i_p_2 _-_d_c_) decompresses all specified files to | 86 | _b_z_c_a_t (or _b_z_i_p_2 _-_d_c_) decompresses all specified files to |
| @@ -115,7 +101,7 @@ bzip2(1) bzip2(1) | |||
| 115 | 101 | ||
| 116 | As a self-check for your protection, _b_z_i_p_2 uses 32-bit | 102 | As a self-check for your protection, _b_z_i_p_2 uses 32-bit |
| 117 | CRCs to make sure that the decompressed version of a file | 103 | CRCs to make sure that the decompressed version of a file |
| 118 | is identical to the original. This guards against corrup- | 104 | is identical to the original. This guards against corrup |
| 119 | tion of the compressed data, and against undetected bugs | 105 | tion of the compressed data, and against undetected bugs |
| 120 | in _b_z_i_p_2 (hopefully very unlikely). The chances of data | 106 | in _b_z_i_p_2 (hopefully very unlikely). The chances of data |
| 121 | corruption going undetected is microscopic, about one | 107 | corruption going undetected is microscopic, about one |
| @@ -125,17 +111,6 @@ bzip2(1) bzip2(1) | |||
| 125 | you recover the original uncompressed data. You can use | 111 | you recover the original uncompressed data. You can use |
| 126 | _b_z_i_p_2_r_e_c_o_v_e_r to try to recover data from damaged files. | 112 | _b_z_i_p_2_r_e_c_o_v_e_r to try to recover data from damaged files. |
| 127 | 113 | ||
| 128 | |||
| 129 | |||
| 130 | 2 | ||
| 131 | |||
| 132 | |||
| 133 | |||
| 134 | |||
| 135 | |||
| 136 | bzip2(1) bzip2(1) | ||
| 137 | |||
| 138 | |||
| 139 | Return values: 0 for a normal exit, 1 for environmental | 114 | Return values: 0 for a normal exit, 1 for environmental |
| 140 | problems (file not found, invalid flags, I/O errors, &c), | 115 | problems (file not found, invalid flags, I/O errors, &c), |
| 141 | 2 to indicate a corrupt compressed file, 3 for an internal | 116 | 2 to indicate a corrupt compressed file, 3 for an internal |
| @@ -154,8 +129,8 @@ OOPPTTIIOONNSS | |||
| 154 | and forces _b_z_i_p_2 to decompress. | 129 | and forces _b_z_i_p_2 to decompress. |
| 155 | 130 | ||
| 156 | --zz ----ccoommpprreessss | 131 | --zz ----ccoommpprreessss |
| 157 | The complement to -d: forces compression, regard- | 132 | The complement to -d: forces compression, |
| 158 | less of the invokation name. | 133 | regardless of the invocation name. |
| 159 | 134 | ||
| 160 | --tt ----tteesstt | 135 | --tt ----tteesstt |
| 161 | Check integrity of the specified file(s), but don't | 136 | Check integrity of the specified file(s), but don't |
| @@ -168,6 +143,11 @@ OOPPTTIIOONNSS | |||
| 168 | forces _b_z_i_p_2 to break hard links to files, which it | 143 | forces _b_z_i_p_2 to break hard links to files, which it |
| 169 | otherwise wouldn't do. | 144 | otherwise wouldn't do. |
| 170 | 145 | ||
| 146 | bzip2 normally declines to decompress files which | ||
| 147 | don't have the correct magic header bytes. If | ||
| 148 | forced (-f), however, it will pass such files | ||
| 149 | through unmodified. This is how GNU gzip behaves. | ||
| 150 | |||
| 171 | --kk ----kkeeeepp | 151 | --kk ----kkeeeepp |
| 172 | Keep (don't delete) input files during compression | 152 | Keep (don't delete) input files during compression |
| 173 | or decompression. | 153 | or decompression. |
| @@ -190,23 +170,11 @@ OOPPTTIIOONNSS | |||
| 190 | --qq ----qquuiieett | 170 | --qq ----qquuiieett |
| 191 | Suppress non-essential warning messages. Messages | 171 | Suppress non-essential warning messages. Messages |
| 192 | pertaining to I/O errors and other critical events | 172 | pertaining to I/O errors and other critical events |
| 193 | |||
| 194 | |||
| 195 | |||
| 196 | 3 | ||
| 197 | |||
| 198 | |||
| 199 | |||
| 200 | |||
| 201 | |||
| 202 | bzip2(1) bzip2(1) | ||
| 203 | |||
| 204 | |||
| 205 | will not be suppressed. | 173 | will not be suppressed. |
| 206 | 174 | ||
| 207 | --vv ----vveerrbboossee | 175 | --vv ----vveerrbboossee |
| 208 | Verbose mode -- show the compression ratio for each | 176 | Verbose mode -- show the compression ratio for each |
| 209 | file processed. Further -v's increase the ver- | 177 | file processed. Further -v's increase the ver |
| 210 | bosity level, spewing out lots of information which | 178 | bosity level, spewing out lots of information which |
| 211 | is primarily of interest for diagnostic purposes. | 179 | is primarily of interest for diagnostic purposes. |
| 212 | 180 | ||
| @@ -214,20 +182,24 @@ bzip2(1) bzip2(1) | |||
| 214 | Display the software version, license terms and | 182 | Display the software version, license terms and |
| 215 | conditions. | 183 | conditions. |
| 216 | 184 | ||
| 217 | --11 ttoo --99 | 185 | --11 ((oorr ----ffaasstt)) ttoo --99 ((oorr ----bbeesstt)) |
| 218 | Set the block size to 100 k, 200 k .. 900 k when | 186 | Set the block size to 100 k, 200 k .. 900 k when |
| 219 | compressing. Has no effect when decompressing. | 187 | compressing. Has no effect when decompressing. |
| 220 | See MEMORY MANAGEMENT below. | 188 | See MEMORY MANAGEMENT below. The --fast and --best |
| 189 | aliases are primarily for GNU gzip compatibility. | ||
| 190 | In particular, --fast doesn't make things signifi | ||
| 191 | cantly faster. And --best merely selects the | ||
| 192 | default behaviour. | ||
| 221 | 193 | ||
| 222 | ---- Treats all subsequent arguments as file names, even | 194 | ---- Treats all subsequent arguments as file names, even |
| 223 | if they start with a dash. This is so you can han- | 195 | if they start with a dash. This is so you can han |
| 224 | dle files with names beginning with a dash, for | 196 | dle files with names beginning with a dash, for |
| 225 | example: bzip2 -- -myfilename. | 197 | example: bzip2 -- -myfilename. |
| 226 | 198 | ||
| 227 | ----rreeppeettiittiivvee--ffaasstt ----rreeppeettiittiivvee--bbeesstt | 199 | ----rreeppeettiittiivvee--ffaasstt ----rreeppeettiittiivvee--bbeesstt |
| 228 | These flags are redundant in versions 0.9.5 and | 200 | These flags are redundant in versions 0.9.5 and |
| 229 | above. They provided some coarse control over the | 201 | above. They provided some coarse control over the |
| 230 | behaviour of the sorting algorithm in earlier ver- | 202 | behaviour of the sorting algorithm in earlier ver |
| 231 | sions, which was sometimes useful. 0.9.5 and above | 203 | sions, which was sometimes useful. 0.9.5 and above |
| 232 | have an improved algorithm which renders these | 204 | have an improved algorithm which renders these |
| 233 | flags irrelevant. | 205 | flags irrelevant. |
| @@ -238,7 +210,7 @@ MMEEMMOORRYY MMAANNAAGGEEMMEENNTT | |||
| 238 | affects both the compression ratio achieved, and the | 210 | affects both the compression ratio achieved, and the |
| 239 | amount of memory needed for compression and decompression. | 211 | amount of memory needed for compression and decompression. |
| 240 | The flags -1 through -9 specify the block size to be | 212 | The flags -1 through -9 specify the block size to be |
| 241 | 100,000 bytes through 900,000 bytes (the default) respec- | 213 | 100,000 bytes through 900,000 bytes (the default) respec |
| 242 | tively. At decompression time, the block size used for | 214 | tively. At decompression time, the block size used for |
| 243 | compression is read from the header of the compressed | 215 | compression is read from the header of the compressed |
| 244 | file, and _b_u_n_z_i_p_2 then allocates itself just enough memory | 216 | file, and _b_u_n_z_i_p_2 then allocates itself just enough memory |
| @@ -256,18 +228,6 @@ MMEEMMOORRYY MMAANNAAGGEEMMEENNTT | |||
| 256 | 228 | ||
| 257 | Larger block sizes give rapidly diminishing marginal | 229 | Larger block sizes give rapidly diminishing marginal |
| 258 | returns. Most of the compression comes from the first two | 230 | returns. Most of the compression comes from the first two |
| 259 | |||
| 260 | |||
| 261 | |||
| 262 | 4 | ||
| 263 | |||
| 264 | |||
| 265 | |||
| 266 | |||
| 267 | |||
| 268 | bzip2(1) bzip2(1) | ||
| 269 | |||
| 270 | |||
| 271 | or three hundred k of block size, a fact worth bearing in | 231 | or three hundred k of block size, a fact worth bearing in |
| 272 | mind when using _b_z_i_p_2 on small machines. It is also | 232 | mind when using _b_z_i_p_2 on small machines. It is also |
| 273 | important to appreciate that the decompression memory | 233 | important to appreciate that the decompression memory |
| @@ -278,13 +238,13 @@ bzip2(1) bzip2(1) | |||
| 278 | _b_u_n_z_i_p_2 will require about 3700 kbytes to decompress. To | 238 | _b_u_n_z_i_p_2 will require about 3700 kbytes to decompress. To |
| 279 | support decompression of any file on a 4 megabyte machine, | 239 | support decompression of any file on a 4 megabyte machine, |
| 280 | _b_u_n_z_i_p_2 has an option to decompress using approximately | 240 | _b_u_n_z_i_p_2 has an option to decompress using approximately |
| 281 | half this amount of memory, about 2300 kbytes. Decompres- | 241 | half this amount of memory, about 2300 kbytes. Decompres |
| 282 | sion speed is also halved, so you should use this option | 242 | sion speed is also halved, so you should use this option |
| 283 | only where necessary. The relevant flag is -s. | 243 | only where necessary. The relevant flag is -s. |
| 284 | 244 | ||
| 285 | In general, try and use the largest block size memory con- | 245 | In general, try and use the largest block size memory con |
| 286 | straints allow, since that maximises the compression | 246 | straints allow, since that maximises the compression |
| 287 | achieved. Compression and decompression speed are virtu- | 247 | achieved. Compression and decompression speed are virtu |
| 288 | ally unaffected by block size. | 248 | ally unaffected by block size. |
| 289 | 249 | ||
| 290 | Another significant point applies to files which fit in a | 250 | Another significant point applies to files which fit in a |
| @@ -300,11 +260,11 @@ bzip2(1) bzip2(1) | |||
| 300 | 260 | ||
| 301 | Here is a table which summarises the maximum memory usage | 261 | Here is a table which summarises the maximum memory usage |
| 302 | for different block sizes. Also recorded is the total | 262 | for different block sizes. Also recorded is the total |
| 303 | compressed size for 14 files of the Calgary Text Compres- | 263 | compressed size for 14 files of the Calgary Text Compres |
| 304 | sion Corpus totalling 3,141,622 bytes. This column gives | 264 | sion Corpus totalling 3,141,622 bytes. This column gives |
| 305 | some feel for how compression varies with block size. | 265 | some feel for how compression varies with block size. |
| 306 | These figures tend to understate the advantage of larger | 266 | These figures tend to understate the advantage of larger |
| 307 | block sizes for larger files, since the Corpus is domi- | 267 | block sizes for larger files, since the Corpus is domi |
| 308 | nated by smaller files. | 268 | nated by smaller files. |
| 309 | 269 | ||
| 310 | Compress Decompress Decompress Corpus | 270 | Compress Decompress Decompress Corpus |
| @@ -321,22 +281,9 @@ bzip2(1) bzip2(1) | |||
| 321 | -9 7600k 3700k 2350k 828642 | 281 | -9 7600k 3700k 2350k 828642 |
| 322 | 282 | ||
| 323 | 283 | ||
| 324 | |||
| 325 | |||
| 326 | |||
| 327 | |||
| 328 | 5 | ||
| 329 | |||
| 330 | |||
| 331 | |||
| 332 | |||
| 333 | |||
| 334 | bzip2(1) bzip2(1) | ||
| 335 | |||
| 336 | |||
| 337 | RREECCOOVVEERRIINNGG DDAATTAA FFRROOMM DDAAMMAAGGEEDD FFIILLEESS | 284 | RREECCOOVVEERRIINNGG DDAATTAA FFRROOMM DDAAMMAAGGEEDD FFIILLEESS |
| 338 | _b_z_i_p_2 compresses files in blocks, usually 900kbytes long. | 285 | _b_z_i_p_2 compresses files in blocks, usually 900kbytes long. |
| 339 | Each block is handled independently. If a media or trans- | 286 | Each block is handled independently. If a media or trans |
| 340 | mission error causes a multi-block .bz2 file to become | 287 | mission error causes a multi-block .bz2 file to become |
| 341 | damaged, it may be possible to recover data from the | 288 | damaged, it may be possible to recover data from the |
| 342 | undamaged blocks in the file. | 289 | undamaged blocks in the file. |
| @@ -353,19 +300,19 @@ RREECCOOVVEERRIINNGG DDAATTAA FFRROOMM DDAAMMAAGGEEDD F | |||
| 353 | the integrity of the resulting files, and decompress those | 300 | the integrity of the resulting files, and decompress those |
| 354 | which are undamaged. | 301 | which are undamaged. |
| 355 | 302 | ||
| 356 | _b_z_i_p_2_r_e_c_o_v_e_r takes a single argument, the name of the dam- | 303 | _b_z_i_p_2_r_e_c_o_v_e_r takes a single argument, the name of the dam |
| 357 | aged file, and writes a number of files "rec0001file.bz2", | 304 | aged file, and writes a number of files |
| 358 | "rec0002file.bz2", etc, containing the extracted blocks. | 305 | "rec00001file.bz2", "rec00002file.bz2", etc, containing |
| 359 | The output filenames are designed so that the use of | 306 | the extracted blocks. The output filenames are |
| 360 | wildcards in subsequent processing -- for example, "bzip2 | 307 | designed so that the use of wildcards in subsequent pro |
| 361 | -dc rec*file.bz2 > recovered_data" -- lists the files in | 308 | cessing -- for example, "bzip2 -dc rec*file.bz2 > recov |
| 362 | the correct order. | 309 | ered_data" -- processes the files in the correct order. |
| 363 | 310 | ||
| 364 | _b_z_i_p_2_r_e_c_o_v_e_r should be of most use dealing with large .bz2 | 311 | _b_z_i_p_2_r_e_c_o_v_e_r should be of most use dealing with large .bz2 |
| 365 | files, as these will contain many blocks. It is clearly | 312 | files, as these will contain many blocks. It is clearly |
| 366 | futile to use it on damaged single-block files, since a | 313 | futile to use it on damaged single-block files, since a |
| 367 | damaged block cannot be recovered. If you wish to min- | 314 | damaged block cannot be recovered. If you wish to min |
| 368 | imise any potential data loss through media or transmis- | 315 | imise any potential data loss through media or transmis |
| 369 | sion errors, you might consider compressing with a smaller | 316 | sion errors, you might consider compressing with a smaller |
| 370 | block size. | 317 | block size. |
| 371 | 318 | ||
| @@ -379,31 +326,19 @@ PPEERRFFOORRMMAANNCCEE NNOOTTEESS | |||
| 379 | better than previous versions in this respect. The ratio | 326 | better than previous versions in this respect. The ratio |
| 380 | between worst-case and average-case compression time is in | 327 | between worst-case and average-case compression time is in |
| 381 | the region of 10:1. For previous versions, this figure | 328 | the region of 10:1. For previous versions, this figure |
| 382 | was more like 100:1. You can use the -vvvv option to mon- | 329 | was more like 100:1. You can use the -vvvv option to mon |
| 383 | itor progress in great detail, if you want. | 330 | itor progress in great detail, if you want. |
| 384 | 331 | ||
| 385 | Decompression speed is unaffected by these phenomena. | 332 | Decompression speed is unaffected by these phenomena. |
| 386 | 333 | ||
| 387 | _b_z_i_p_2 usually allocates several megabytes of memory to | 334 | _b_z_i_p_2 usually allocates several megabytes of memory to |
| 388 | operate in, and then charges all over it in a fairly ran- | 335 | operate in, and then charges all over it in a fairly ran |
| 389 | dom fashion. This means that performance, both for com- | 336 | dom fashion. This means that performance, both for com |
| 390 | pressing and decompressing, is largely determined by the | 337 | pressing and decompressing, is largely determined by the |
| 391 | |||
| 392 | |||
| 393 | |||
| 394 | 6 | ||
| 395 | |||
| 396 | |||
| 397 | |||
| 398 | |||
| 399 | |||
| 400 | bzip2(1) bzip2(1) | ||
| 401 | |||
| 402 | |||
| 403 | speed at which your machine can service cache misses. | 338 | speed at which your machine can service cache misses. |
| 404 | Because of this, small changes to the code to reduce the | 339 | Because of this, small changes to the code to reduce the |
| 405 | miss rate have been observed to give disproportionately | 340 | miss rate have been observed to give disproportionately |
| 406 | large performance improvements. I imagine _b_z_i_p_2 will per- | 341 | large performance improvements. I imagine _b_z_i_p_2 will per |
| 407 | form best on machines with very large caches. | 342 | form best on machines with very large caches. |
| 408 | 343 | ||
| 409 | 344 | ||
| @@ -413,50 +348,51 @@ CCAAVVEEAATTSS | |||
| 413 | but the details of what the problem is sometimes seem | 348 | but the details of what the problem is sometimes seem |
| 414 | rather misleading. | 349 | rather misleading. |
| 415 | 350 | ||
| 416 | This manual page pertains to version 1.0 of _b_z_i_p_2_. Com- | 351 | This manual page pertains to version 1.0.2 of _b_z_i_p_2_. Com |
| 417 | pressed data created by this version is entirely forwards | 352 | pressed data created by this version is entirely forwards |
| 418 | and backwards compatible with the previous public | 353 | and backwards compatible with the previous public |
| 419 | releases, versions 0.1pl2, 0.9.0 and 0.9.5, but with the | 354 | releases, versions 0.1pl2, 0.9.0, 0.9.5, 1.0.0 and 1.0.1, |
| 420 | following exception: 0.9.0 and above can correctly decom- | 355 | but with the following exception: 0.9.0 and above can cor |
| 421 | press multiple concatenated compressed files. 0.1pl2 can- | 356 | rectly decompress multiple concatenated compressed files. |
| 422 | not do this; it will stop after decompressing just the | 357 | 0.1pl2 cannot do this; it will stop after decompressing |
| 423 | first file in the stream. | 358 | just the first file in the stream. |
| 359 | |||
| 360 | _b_z_i_p_2_r_e_c_o_v_e_r versions prior to this one, 1.0.2, used | ||
| 361 | 32-bit integers to represent bit positions in compressed | ||
| 362 | files, so it could not handle compressed files more than | ||
| 363 | 512 megabytes long. Version 1.0.2 and above uses 64-bit | ||
| 364 | ints on some platforms which support them (GNU supported | ||
| 365 | targets, and Windows). To establish whether or not | ||
| 366 | bzip2recover was built with such a limitation, run it | ||
| 367 | without arguments. In any event you can build yourself an | ||
| 368 | unlimited version if you can recompile it with MaybeUInt64 | ||
| 369 | set to be an unsigned 64-bit integer. | ||
| 370 | |||
| 424 | 371 | ||
| 425 | _b_z_i_p_2_r_e_c_o_v_e_r uses 32-bit integers to represent bit posi- | ||
| 426 | tions in compressed files, so it cannot handle compressed | ||
| 427 | files more than 512 megabytes long. This could easily be | ||
| 428 | fixed. | ||
| 429 | 372 | ||
| 430 | 373 | ||
| 431 | AAUUTTHHOORR | 374 | AAUUTTHHOORR |
| 432 | Julian Seward, jseward@acm.org. | 375 | Julian Seward, jseward@acm.org. |
| 433 | 376 | ||
| 434 | http://sourceware.cygnus.com/bzip2 | 377 | http://sources.redhat.com/bzip2 |
| 435 | http://www.muraroa.demon.co.uk | ||
| 436 | 378 | ||
| 437 | The ideas embodied in _b_z_i_p_2 are due to (at least) the fol- | 379 | The ideas embodied in _b_z_i_p_2 are due to (at least) the fol |
| 438 | lowing people: Michael Burrows and David Wheeler (for the | 380 | lowing people: Michael Burrows and David Wheeler (for the |
| 439 | block sorting transformation), David Wheeler (again, for | 381 | block sorting transformation), David Wheeler (again, for |
| 440 | the Huffman coder), Peter Fenwick (for the structured cod- | 382 | the Huffman coder), Peter Fenwick (for the structured cod |
| 441 | ing model in the original _b_z_i_p_, and many refinements), and | 383 | ing model in the original _b_z_i_p_, and many refinements), and |
| 442 | Alistair Moffat, Radford Neal and Ian Witten (for the | 384 | Alistair Moffat, Radford Neal and Ian Witten (for the |
| 443 | arithmetic coder in the original _b_z_i_p_)_. I am much | 385 | arithmetic coder in the original _b_z_i_p_)_. I am much |
| 444 | indebted for their help, support and advice. See the man- | 386 | indebted for their help, support and advice. See the man |
| 445 | ual in the source distribution for pointers to sources of | 387 | ual in the source distribution for pointers to sources of |
| 446 | documentation. Christian von Roques encouraged me to look | 388 | documentation. Christian von Roques encouraged me to look |
| 447 | for faster sorting algorithms, so as to speed up compres- | 389 | for faster sorting algorithms, so as to speed up compres |
| 448 | sion. Bela Lubkin encouraged me to improve the worst-case | 390 | sion. Bela Lubkin encouraged me to improve the worst-case |
| 449 | compression performance. Many people sent patches, helped | 391 | compression performance. The bz* scripts are derived from |
| 450 | with portability problems, lent machines, gave advice and | 392 | those of GNU gzip. Many people sent patches, helped with |
| 451 | were generally helpful. | 393 | portability problems, lent machines, gave advice and were |
| 452 | 394 | generally helpful. | |
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| 459 | 395 | ||
| 460 | 7 | ||
| 461 | 396 | ||
| 462 | 397 | ||
| 398 | bzip2(1) | ||
