, I for the precedence of " "internationalization variables used to determine the values of locale " "categories.)" msgstr "" #. type: IP #: man-pages-posix/man1p/cksum.1p:106 #, no-wrap msgid "I" msgstr "" #. type: Plain text #: man-pages-posix/man1p/cksum.1p:109 msgid "" "If set to a non-empty string value, override the values of all the other " "internationalization variables." msgstr "" #. type: IP #: man-pages-posix/man1p/cksum.1p:109 #, no-wrap msgid "I" msgstr "" #. type: Plain text #: man-pages-posix/man1p/cksum.1p:113 msgid "" "Determine the locale for the interpretation of sequences of bytes of text " "data as characters (for example, single-byte as opposed to multi-byte " "characters in arguments)." msgstr "" #. type: IP #: man-pages-posix/man1p/cksum.1p:113 #, no-wrap msgid "I" msgstr "" #. type: Plain text #: man-pages-posix/man1p/cksum.1p:117 msgid "" "Determine the locale that should be used to affect the format and contents " "of diagnostic messages written to standard error." msgstr "" #. type: IP #: man-pages-posix/man1p/cksum.1p:117 #, no-wrap msgid "I" msgstr "" #. type: Plain text #: man-pages-posix/man1p/cksum.1p:120 msgid "" "Determine the location of message catalogs for the processing of " "I." msgstr "" #. type: SH #: man-pages-posix/man1p/cksum.1p:120 #, no-wrap msgid "ASYNCHRONOUS EVENTS" msgstr "" #. type: Plain text #: man-pages-posix/man1p/cksum.1p:122 man-pages-posix/man1p/cksum.1p:154 msgid "Default." msgstr "" #. type: SH #: man-pages-posix/man1p/cksum.1p:122 #, no-wrap msgid "STDOUT" msgstr "" #. type: Plain text #: man-pages-posix/man1p/cksum.1p:126 msgid "" "For each file processed successfully, the I utility shall write in " "the following format:" msgstr "" #. type: Plain text #: man-pages-posix/man1p/cksum.1p:131 #, no-wrap msgid "" "B<\n" "\"%u %d %s\\en\", E>IE, EI<# of octets>E, " "EIE\n" msgstr "" #. type: Plain text #: man-pages-posix/man1p/cksum.1p:140 msgid "" "If no I operand was specified, the pathname and its leading " "EspaceE shall be omitted." msgstr "" #. type: SH #: man-pages-posix/man1p/cksum.1p:140 #, no-wrap msgid "STDERR" msgstr "" #. type: Plain text #: man-pages-posix/man1p/cksum.1p:142 msgid "The standard error shall be used only for diagnostic messages." msgstr "" #. type: SH #: man-pages-posix/man1p/cksum.1p:142 #, no-wrap msgid "OUTPUT FILES" msgstr "" #. type: SH #: man-pages-posix/man1p/cksum.1p:144 #, no-wrap msgid "EXTENDED DESCRIPTION" msgstr "" #. type: SH #: man-pages-posix/man1p/cksum.1p:146 #, no-wrap msgid "EXIT STATUS" msgstr "" #. type: Plain text #: man-pages-posix/man1p/cksum.1p:148 msgid "The following exit values shall be returned:" msgstr "" #. type: IP #: man-pages-posix/man1p/cksum.1p:148 #, no-wrap msgid "\\00" msgstr "" #. type: Plain text #: man-pages-posix/man1p/cksum.1p:150 msgid "All files were processed successfully." msgstr "" #. type: IP #: man-pages-posix/man1p/cksum.1p:150 #, no-wrap msgid "E0" msgstr "" #. type: Plain text #: man-pages-posix/man1p/cksum.1p:152 msgid "An error occurred." msgstr "" #. type: SH #: man-pages-posix/man1p/cksum.1p:152 #, no-wrap msgid "CONSEQUENCES OF ERRORS" msgstr "" #. type: Plain text #: man-pages-posix/man1p/cksum.1p:156 msgid "I" msgstr "" #. type: SH #: man-pages-posix/man1p/cksum.1p:156 #, no-wrap msgid "APPLICATION USAGE" msgstr "" #. type: Plain text #: man-pages-posix/man1p/cksum.1p:165 msgid "" "The I utility is typically used to quickly compare a suspect file " "against a trusted version of the same, such as to ensure that files " "transmitted over noisy media arrive intact. However, this comparison cannot " "be considered cryptographically secure. The chances of a damaged file " "producing the same CRC as the original are small; deliberate deception is " "difficult, but probably not impossible." msgstr "" #. type: Plain text #: man-pages-posix/man1p/cksum.1p:173 msgid "" "Although input files to I can be any type, the results need not be " "what would be expected on character special device files or on file types " "not described by the System Interfaces volume of POSIX.1\\(hy2008. Since " "this volume of POSIX.1\\(hy2008 does not specify the block size used when " "doing input, checksums of character special files need not process all of " "the data in those files." msgstr "" #. type: Plain text #: man-pages-posix/man1p/cksum.1p:181 msgid "" "The algorithm is expressed in terms of a bitstream divided into octets. If " "a file is transmitted between two systems and undergoes any data " "transformation (such as changing little-endian byte ordering to big-endian), " "identical CRC values cannot be expected. Implementations performing such " "transformations may extend I to handle such situations." msgstr "" #. type: SH #: man-pages-posix/man1p/cksum.1p:181 #, no-wrap msgid "EXAMPLES" msgstr "" #. type: SH #: man-pages-posix/man1p/cksum.1p:183 #, no-wrap msgid "RATIONALE" msgstr "" #. type: Plain text #: man-pages-posix/man1p/cksum.1p:190 msgid "" "The following C-language program can be used as a model to describe the " "algorithm. It assumes that a B is one octet. It also assumes that the " "entire file is available for one pass through the function. This was done " "for simplicity in demonstrating the algorithm, rather than as an " "implementation model." msgstr "" #. type: Plain text #: man-pages-posix/man1p/cksum.1p:248 #, no-wrap msgid "" "B<\n" "static unsigned long crctab[] = {\n" "0x00000000,\n" "0x04c11db7, 0x09823b6e, 0x0d4326d9, 0x130476dc, 0x17c56b6b,\n" "0x1a864db2, 0x1e475005, 0x2608edb8, 0x22c9f00f, 0x2f8ad6d6,\n" "0x2b4bcb61, 0x350c9b64, 0x31cd86d3, 0x3c8ea00a, 0x384fbdbd,\n" "0x4c11db70, 0x48d0c6c7, 0x4593e01e, 0x4152fda9, 0x5f15adac,\n" "0x5bd4b01b, 0x569796c2, 0x52568b75, 0x6a1936c8, 0x6ed82b7f,\n" "0x639b0da6, 0x675a1011, 0x791d4014, 0x7ddc5da3, 0x709f7b7a,\n" "0x745e66cd, 0x9823b6e0, 0x9ce2ab57, 0x91a18d8e, 0x95609039,\n" "0x8b27c03c, 0x8fe6dd8b, 0x82a5fb52, 0x8664e6e5, 0xbe2b5b58,\n" "0xbaea46ef, 0xb7a96036, 0xb3687d81, 0xad2f2d84, 0xa9ee3033,\n" "0xa4ad16ea, 0xa06c0b5d, 0xd4326d90, 0xd0f37027, 0xddb056fe,\n" "0xd9714b49, 0xc7361b4c, 0xc3f706fb, 0xceb42022, 0xca753d95,\n" "0xf23a8028, 0xf6fb9d9f, 0xfbb8bb46, 0xff79a6f1, 0xe13ef6f4,\n" "0xe5ffeb43, 0xe8bccd9a, 0xec7dd02d, 0x34867077, 0x30476dc0,\n" "0x3d044b19, 0x39c556ae, 0x278206ab, 0x23431b1c, 0x2e003dc5,\n" "0x2ac12072, 0x128e9dcf, 0x164f8078, 0x1b0ca6a1, 0x1fcdbb16,\n" "0x018aeb13, 0x054bf6a4, 0x0808d07d, 0x0cc9cdca, 0x7897ab07,\n" "0x7c56b6b0, 0x71159069, 0x75d48dde, 0x6b93dddb, 0x6f52c06c,\n" "0x6211e6b5, 0x66d0fb02, 0x5e9f46bf, 0x5a5e5b08, 0x571d7dd1,\n" "0x53dc6066, 0x4d9b3063, 0x495a2dd4, 0x44190b0d, 0x40d816ba,\n" "0xaca5c697, 0xa864db20, 0xa527fdf9, 0xa1e6e04e, 0xbfa1b04b,\n" "0xbb60adfc, 0xb6238b25, 0xb2e29692, 0x8aad2b2f, 0x8e6c3698,\n" "0x832f1041, 0x87ee0df6, 0x99a95df3, 0x9d684044, 0x902b669d,\n" "0x94ea7b2a, 0xe0b41de7, 0xe4750050, 0xe9362689, 0xedf73b3e,\n" "0xf3b06b3b, 0xf771768c, 0xfa325055, 0xfef34de2, 0xc6bcf05f,\n" "0xc27dede8, 0xcf3ecb31, 0xcbffd686, 0xd5b88683, 0xd1799b34,\n" "0xdc3abded, 0xd8fba05a, 0x690ce0ee, 0x6dcdfd59, 0x608edb80,\n" "0x644fc637, 0x7a089632, 0x7ec98b85, 0x738aad5c, 0x774bb0eb,\n" "0x4f040d56, 0x4bc510e1, 0x46863638, 0x42472b8f, 0x5c007b8a,\n" "0x58c1663d, 0x558240e4, 0x51435d53, 0x251d3b9e, 0x21dc2629,\n" "0x2c9f00f0, 0x285e1d47, 0x36194d42, 0x32d850f5, 0x3f9b762c,\n" "0x3b5a6b9b, 0x0315d626, 0x07d4cb91, 0x0a97ed48, 0x0e56f0ff,\n" "0x1011a0fa, 0x14d0bd4d, 0x19939b94, 0x1d528623, 0xf12f560e,\n" "0xf5ee4bb9, 0xf8ad6d60, 0xfc6c70d7, 0xe22b20d2, 0xe6ea3d65,\n" "0xeba91bbc, 0xef68060b, 0xd727bbb6, 0xd3e6a601, 0xdea580d8,\n" "0xda649d6f, 0xc423cd6a, 0xc0e2d0dd, 0xcda1f604, 0xc960ebb3,\n" "0xbd3e8d7e, 0xb9ff90c9, 0xb4bcb610, 0xb07daba7, 0xae3afba2,\n" "0xaafbe615, 0xa7b8c0cc, 0xa379dd7b, 0x9b3660c6, 0x9ff77d71,\n" "0x92b45ba8, 0x9675461f, 0x8832161a, 0x8cf30bad, 0x81b02d74,\n" "0x857130c3, 0x5d8a9099, 0x594b8d2e, 0x5408abf7, 0x50c9b640,\n" "0x4e8ee645, 0x4a4ffbf2, 0x470cdd2b, 0x43cdc09c, 0x7b827d21,\n" "0x7f436096, 0x7200464f, 0x76c15bf8, 0x68860bfd, 0x6c47164a,\n" "0x61043093, 0x65c52d24, 0x119b4be9, 0x155a565e, 0x18197087,\n" "0x1cd86d30, 0x029f3d35, 0x065e2082, 0x0b1d065b, 0x0fdc1bec,\n" "0x3793a651, 0x3352bbe6, 0x3e119d3f, 0x3ad08088, 0x2497d08d,\n" "0x2056cd3a, 0x2d15ebe3, 0x29d4f654, 0xc5a92679, 0xc1683bce,\n" "0xcc2b1d17, 0xc8ea00a0, 0xd6ad50a5, 0xd26c4d12, 0xdf2f6bcb,\n" "0xdbee767c, 0xe3a1cbc1, 0xe760d676, 0xea23f0af, 0xeee2ed18,\n" "0xf0a5bd1d, 0xf464a0aa, 0xf9278673, 0xfde69bc4, 0x89b8fd09,\n" "0x8d79e0be, 0x803ac667, 0x84fbdbd0, 0x9abc8bd5, 0x9e7d9662,\n" "0x933eb0bb, 0x97ffad0c, 0xafb010b1, 0xab710d06, 0xa6322bdf,\n" "0xa2f33668, 0xbcb4666d, 0xb8757bda, 0xb5365d03, 0xb1f740b4\n" "};>\n" msgstr "" #. type: Plain text #: man-pages-posix/man1p/cksum.1p:255 #, no-wrap msgid "" "unsigned long memcrc(const unsigned char *b, size_t n)\n" "{\n" "/* Input arguments:\n" " * const unsigned char* b == byte sequence to checksum\n" " * size_t n == length of sequence\n" " */\n" msgstr "" #. type: Plain text #: man-pages-posix/man1p/cksum.1p:258 #, no-wrap msgid " register size_t i;\n" " register unsigned c, s = 0;\n" msgstr "" #. type: Plain text #: man-pages-posix/man1p/cksum.1p:263 #, no-wrap msgid "" " for (i = n; i E 0; \\(mi\\|\\(mii) {\n" " c = *b++;\n" " s = (s EE 8) ^ crctab[(s EE 24) ^ c];\n" " }\n" msgstr "" #. type: Plain text #: man-pages-posix/man1p/cksum.1p:270 #, no-wrap msgid "" " /* Extend with the length of the string. */\n" " while (n != 0) {\n" " c = n & 0377;\n" " n EE= 8;\n" " s = (s EE 8) ^ crctab[(s EE 24) ^ c];\n" " }\n" msgstr "" #. type: Plain text #: man-pages-posix/man1p/cksum.1p:273 #, no-wrap msgid " return ~s;\n" "}\n" msgstr "" #. type: Plain text #: man-pages-posix/man1p/cksum.1p:281 msgid "" "The historical practice of writing the number of ``blocks'' has been changed " "to writing the number of octets, since the latter is not only more useful, " "but also since historical implementations have not been consistent in " "defining what a ``block'' meant." msgstr "" #. type: Plain text #: man-pages-posix/man1p/cksum.1p:296 msgid "" "The algorithm used was selected to increase the operational robustness of " "I. Neither the System V nor BSD I algorithm was selected. Since " "each of these was different and each was the default behavior on those " "systems, no realistic compromise was available if either were " "selected\\(emsome set of historical applications would break. Therefore, the " "name was changed to I. Although the historical I commands will " "probably continue to be provided for many years, programs designed for " "portability across systems should use the new name." msgstr "" #. type: Plain text #: man-pages-posix/man1p/cksum.1p:312 msgid "" "The algorithm selected is based on that used by the ISO/IEC\\ 8802\\(hy3:" "\\|1996 standard (Ethernet) for the frame check sequence field. The " "algorithm used does not match the technical definition of a I; the " "term is used for historical reasons. The length of the file is included in " "the CRC calculation because this parallels inclusion of a length field by " "Ethernet in its CRC, but also because it guards against inadvertent " "collisions between files that begin with different series of zero octets. " "The chance that two different files produce identical CRCs is much greater " "when their lengths are not considered. Keeping the length and the checksum " "of the file itself separate would yield a slightly more robust algorithm, " "but historical usage has always been that a single number (the checksum as " "printed) represents the signature of the file. It was decided that " "historical usage was the more important consideration." msgstr "" #. type: Plain text #: man-pages-posix/man1p/cksum.1p:317 msgid "" "Early proposals contained modifications to the Ethernet algorithm that " "involved extracting table values whenever an intermediate result became zero." " This was demonstrated to be less robust than the current method and " "mathematically difficult to describe or justify." msgstr "" #. type: Plain text #: man-pages-posix/man1p/cksum.1p:320 msgid "" "The calculation used is identical to that given in pseudo-code in the " "referenced Sarwate article. The pseudo-code rendition is:" msgstr "" #. type: Plain text #: man-pages-posix/man1p/cksum.1p:333 #, no-wrap msgid "" "B<\n" "X E\\(mi 0; Y E\\(mi 0;\n" "for i E\\(mi m \\(mi1 step \\(mi1 until 0 do\n" " begin\n" " T E\\(mi X(1) ^ A[i];\n" " X(1) E\\(mi X(0); X(0) E\\(mi Y(1); Y(1) E\\(mi Y(0); Y(0) " "E\\(mi 0;\n" " comment: f[T] and f'[T] denote the T-th words in the\n" " table f and f' ;\n" " X E\\(mi X ^ f[T]; Y E\\(mi Y ^ f'[T];\n" " end>\n" msgstr "" #. type: Plain text #: man-pages-posix/man1p/cksum.1p:350 msgid "" "The pseudo-code is reproduced exactly as given; however, note that in the " "case of I, B represents a byte of the file, the words B and " "B are treated as a single 32-bit value, and the tables B and B are " "a single table containing 32-bit values." msgstr "" #. type: Plain text #: man-pages-posix/man1p/cksum.1p:352 msgid "The referenced Sarwate article also discusses generating the table." msgstr "" #. type: SH #: man-pages-posix/man1p/cksum.1p:352 #, no-wrap msgid "FUTURE DIRECTIONS" msgstr "" #. type: SH #: man-pages-posix/man1p/cksum.1p:354 #, no-wrap msgid "SEE ALSO" msgstr "" #. type: Plain text #: man-pages-posix/man1p/cksum.1p:357 msgid "" "The Base Definitions volume of POSIX.1\\(hy2008, I, I" msgstr "" #. type: SH #: man-pages-posix/man1p/cksum.1p:357 #, no-wrap msgid "COPYRIGHT" msgstr "" #. type: Plain text #: man-pages-posix/man1p/cksum.1p:368 msgid "" "Portions of this text are reprinted and reproduced in electronic form from " "IEEE Std 1003.1, 2013 Edition, Standard for Information Technology -- " "Portable Operating System Interface (POSIX), The Open Group Base " "Specifications Issue 7, Copyright (C) 2013 by the Institute of Electrical " "and Electronics Engineers, Inc and The Open Group. (This is POSIX.1-2008 " "with the 2013 Technical Corrigendum 1 applied.) In the event of any " "discrepancy between this version and the original IEEE and The Open Group " "Standard, the original IEEE and The Open Group Standard is the referee " "document. The original Standard can be obtained online at http://www.unix." "org/online.html ." msgstr "" #. type: Plain text #: man-pages-posix/man1p/cksum.1p:373 msgid "" "Any typographical or formatting errors that appear in this page are most " "likely to have been introduced during the conversion of the source files to " "man page format. To report such errors, see https://www.kernel.org/doc/man-" "pages/reporting_bugs.html ." msgstr ""