u s t a r \040 \040 \0 (for old GNU tar format)
89-480: TBZ, tbz , or TbZ can refer to: A computer file, the result of tar and bzip2 operations. Tetrabenazine , a drug Thiabendazole , a parasiticide Tabriz International Airport Tahnoun bin Zayed Al Nahyan (national security advisor) , National Security Advisor of UAE The ICAO Airline Designator of Iranian ATA Airlines Topics referred to by
178-400: A 60-bit word without having to split a byte between one word and the next. If longer bytes were needed, 60 bits would, of course, no longer be ideal. With present applications, 1, 4, and 6 bits are the really important cases. With 64-bit words, it would often be necessary to make some compromises, such as leaving 4 bits unused in a word when dealing with 6-bit bytes at
267-467: A 64-bit word length for Stretch. It also supports NSA 's requirement for 8-bit bytes. Werner's term "Byte" first popularized in this memo. NB. This timeline erroneously specifies the birth date of the term "byte" as July 1956 , while Buchholz actually used the term as early as June 1956 . [...] 60 is a multiple of 1, 2, 3, 4, 5, and 6. Hence bytes of length from 1 to 6 bits can be packed efficiently into
356-465: A birth certificate. But I am sure that "byte" is coming of age in 1977 with its 21st birthday. Many have assumed that byte, meaning 8 bits, originated with the IBM System/360, which spread such bytes far and wide in the mid-1960s. The editor is correct in pointing out that the term goes back to the earlier Stretch computer (but incorrect in that Stretch was the first, not
445-476: A convenience, because 1024 is approximately 1000 . This definition was popular in early decades of personal computing , with products like the Tandon 5 1 ⁄ 4 -inch DD floppy format (holding 368 640 bytes) being advertised as "360 KB", following the 1024 -byte convention. It was not universal, however. The Shugart SA-400 5 1 ⁄ 4 -inch floppy disk held 109,375 bytes unformatted, and
534-484: A full transmission unit usually additionally includes a start bit, 1 or 2 stop bits, and possibly a parity bit , and thus its size may vary from seven to twelve bits for five to eight bits of actual data. For synchronous communication the error checking usually uses bytes at the end of a frame . Terms used here to describe the structure imposed by the machine design, in addition to bit , are listed below. Byte denotes
623-475: A group of bits used to encode a character, or the number of bits transmitted in parallel to and from input-output units. A term other than character is used here because a given character may be represented in different applications by more than one code, and different codes may use different numbers of bits (i.e., different byte sizes). In input-output transmission the grouping of bits may be completely arbitrary and have no relation to actual characters. (The term
712-566: A new empty directory and extract the archive into it—or avoid the tar file entirely. Most graphical tools can display the contents of the archive before extracting them. Vim can open tar archives and display their contents. GNU Emacs is also able to open a tar archive and display its contents in a dired buffer. The tar format was designed without a centralized index or table of content for files and their properties for streaming to tape backup devices. The archive must be read sequentially to list or extract files. For large tar archives, this causes
801-406: A number of bits, treated as a unit, and usually representing a character or a part of a character. NOTES: 1 The number of bits in a byte is fixed for a given data processing system. 2 The number of bits in a byte is usually 8. We received the following from W Buchholz, one of the individuals who
890-402: A performance penalty, making tar archives unsuitable for situations that often require random access to individual files. With a well-formed tar file stored on a seekable (i.e. allows efficient random reads) medium, the tar program can still relatively quickly (in linear time relative to file count) look for a file by skipping file reads according to the "size" field in the file headers. This
979-416: A specified date. Basic options: Create an archive file archive.tar from the file README.txt and directory src : Extract contents for the archive.tar into the current directory: Create an archive file archive.tar.gz from the file README.txt and directory src and compress it with gzip : Extract contents for the archive.tar.gz into the current directory: A tarpipe
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#17327932816161068-548: A unit of logarithmic power ratio named after Alexander Graham Bell , creating a conflict with the IEC specification. However, little danger of confusion exists, because the bel is a rarely used unit. It is used primarily in its decadic fraction, the decibel (dB), for signal strength and sound pressure level measurements, while a unit for one-tenth of a byte, the decibyte, and other fractions, are only used in derived units, such as transmission rates. The lowercase letter o for octet
1157-405: A unit which "contains an unspecified amount of information ... capable of holding at least 64 distinct values ... at most 100 distinct values. On a binary computer a byte must therefore be composed of six bits". He notes that "Since 1975 or so, the word byte has come to mean a sequence of precisely eight binary digits...When we speak of bytes in connection with MIX we shall confine ourselves to
1246-406: A user has only a very old tar available, which does not feature those security measures, these problems can be mitigated by first examining a tar file using the command tar tf archive.tar , which lists the contents and allows to exclude problematic files afterwards. These commands do not extract any files, but display the names of all files in the archive. If any are problematic, the user can create
1335-668: Is 1024 bytes = 1024 bytes, one mebibyte (1 MiB) is 1024 bytes = 1 048 576 bytes, and so on. In 1999, Donald Knuth suggested calling the kibibyte a "large kilobyte" ( KKB ). The IEC adopted the IUPAC proposal and published the standard in January 1999. The IEC prefixes are part of the International System of Quantities . The IEC further specified that the kilobyte should only be used to refer to 1000 bytes. Lawsuits arising from alleged consumer confusion over
1424-510: Is coined from bite , but respelled to avoid accidental mutation to bit .) A word consists of the number of data bits transmitted in parallel from or to memory in one memory cycle. Word size is thus defined as a structural property of the memory. (The term catena was coined for this purpose by the designers of the Bull GAMMA 60 [ fr ] computer.) Block refers to
1513-460: Is defined as eight bits. It is a signed data type, holding values from −128 to 127. .NET programming languages, such as C# , define byte as an unsigned type, and the sbyte as a signed data type, holding values from 0 to 255, and −128 to 127 , respectively. In data transmission systems, the byte is used as a contiguous sequence of bits in a serial data stream, representing the smallest distinguished unit of data. For asynchronous communication
1602-455: Is defined as the symbol for octet in IEC ;80000-13 and is commonly used in languages such as French and Romanian , and is also combined with metric prefixes for multiples, for example ko and Mo. More than one system exists to define unit multiples based on the byte. Some systems are based on powers of 10 , following the International System of Units (SI), which defines for example
1691-672: Is defined to equal 1,000 bytes—is recommended by the International Electrotechnical Commission (IEC). The IEC standard defines eight such multiples, up to 1 yottabyte (YB), equal to 1000 bytes. The additional prefixes ronna- for 1000 and quetta- for 1000 were adopted by the International Bureau of Weights and Measures (BIPM) in 2022. This definition is most commonly used for data-rate units in computer networks , internal bus, hard drive and flash media transfer speeds, and for
1780-452: Is designed so that all implementations able to read the UStar format will be able to read the pax format as well. The only exceptions are files that make use of extended features, such as longer file names. For compatibility, these are encoded in the tar files as special x or g type files, typically under a PaxHeaders.XXXX directory. A pax-supporting implementation would make use of
1869-781: Is different from Wikidata All article disambiguation pages All disambiguation pages Tar (file format) In computing , tar is a computer software utility for collecting many files into one archive file , often referred to as a tarball , for distribution or backup purposes. The name is derived from "tape archive", as it was originally developed to write data to sequential I/O devices with no file system of their own, such as devices that use magnetic tape . The archive data sets created by tar contain various file system parameters, such as name, timestamps, ownership, file-access permissions, and directory organization. POSIX abandoned tar in favor of pax , yet tar sees continued widespread use. The command-line utility
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#17327932816161958-618: Is equal to 1,024 (i.e., 2 ) bytes is defined by international standard IEC 80000-13 and is supported by national and international standards bodies ( BIPM , IEC , NIST ). The IEC standard defines eight such multiples, up to 1 yobibyte (YiB), equal to 1024 bytes. The natural binary counterparts to ronna- and quetta- were given in a consultation paper of the International Committee for Weights and Measures' Consultative Committee for Units (CCU) as robi- (Ri, 1024 ) and quebi- (Qi, 1024 ), but have not yet been adopted by
2047-482: Is in use. The UStar format allows for longer file names and stores additional information about each file. The maximum filename size is 256, but it is split among a preceding path "filename prefix" and the filename itself, so can be much less. The type flag field can have the following values: POSIX.1-1988 vendor specific extensions using link flag values 'A'–'Z' partially have a different meaning with different vendors and thus are seen as outdated and replaced by
2136-433: Is just as easy to use all six bits in alphanumeric work, or to handle bytes of only one bit for logical analysis, or to offset the bytes by any number of bits. All this can be done by pulling the appropriate shift diagonals. An analogous matrix arrangement is used to change from serial to parallel operation at the output of the adder. [...] byte: A string that consists of
2225-517: Is known as extended tar format or pax format. The new tar format allows users to add any type of vendor-tagged vendor-specific enhancements. The following tags are defined by the POSIX standard: In 2001, the Star program became the first tar to support the new format. In 2004, GNU tar supported the new format, though it does not write it as its default output from the tar program yet. The pax format
2314-466: Is often called a nibble , also nybble , which is conveniently represented by a single hexadecimal digit. The term octet unambiguously specifies a size of eight bits. It is used extensively in protocol definitions. Historically, the term octad or octade was used to denote eight bits as well at least in Western Europe; however, this usage is no longer common. The exact origin of
2403-461: Is older versions of GNU tar, when running on the MASSCOMP RTU (Real Time Unix) operating system, which supported an O_CTG flag to the open() function to request a contiguous file; however, that support was removed from GNU tar version 1.24 onwards. In 1997, Sun proposed a method for adding extensions to the tar format. This method was later accepted for the POSIX.1-2001 standard. This format
2492-464: Is preceded by a 512-byte header record. The file data is written unaltered except that its length is rounded up to a multiple of 512 bytes. The original tar implementation did not care about the contents of the padding bytes, and left the buffer data unaltered, but most modern tar implementations fill the extra space with zeros. The end of an archive is marked by at least two consecutive zero-filled records. (The origin of tar's record size appears to be
2581-453: Is the basis for option -n in GNU tar. When a tar file is compressed whole, the compression format, being usually non-seekable, prevents this optimization from being done. A number of "indexed" compressors, which are aware of the tar format, can restore this feature for compressed files. To maintain seekability, tar files must be also concatenated properly, by removing the trailing zero block at
2670-579: Is the method of creating an archive on the standard output file of the tar utility and piping it to another tar process on its standard input , working in another directory, where it is unpacked. This process copies an entire source directory tree including all special files, for example: The tar format continues to be used extensively for open-source software distribution . *NIX-distributions use it in various source- and binary-package distribution mechanisms, with most software source code made available in compressed tar archives. The original tar format
2759-557: Is the number of blocks per record. The default is 20, producing 10 KiB records. There are multiple tar file formats, including historical and current ones. Two tar formats are codified in POSIX: ustar and pax . Not codified but still in current use is the GNU tar format. A tar archive consists of a series of file objects, hence the popular term tarball , referencing how a tarball collects objects of all kinds that stick to its surface. Each file object includes any file data, and
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2848-472: Is the smallest addressable unit of memory in many computer architectures . To disambiguate arbitrarily sized bytes from the common 8-bit definition, network protocol documents such as the Internet Protocol ( RFC 791 ) refer to an 8-bit byte as an octet . Those bits in an octet are usually counted with numbering from 0 to 7 or 7 to 0 depending on the bit endianness . The size of
2937-457: Is used here because a given character may be represented in different applications by more than one code, and different codes may use different numbers of bits (ie, different byte sizes). In input-output transmission the grouping of bits may be completely arbitrary and have no relation to actual characters. (The term is coined from bite , but respelled to avoid accidental mutation to bit. ) System/360 took over many of
3026-597: The IRE Transactions on Electronic Computers , June 1959, page 121. The notions of that paper were elaborated in Chapter 4 of Planning a Computer System (Project Stretch) , edited by W Buchholz, McGraw-Hill Book Company (1962). The rationale for coining the term was explained there on page 40 as follows: Byte denotes a group of bits used to encode a character, or the number of bits transmitted in parallel to and from input-output units. A term other than character
3115-649: The American Standard Code for Information Interchange (ASCII) as the Federal Information Processing Standard , which replaced the incompatible teleprinter codes in use by different branches of the U.S. government and universities during the 1960s. ASCII included the distinction of upper- and lowercase alphabets and a set of control characters to facilitate the transmission of written language as well as printing device functions, such as page advance and line feed, and
3204-626: The International Union of Pure and Applied Chemistry 's (IUPAC) Interdivisional Committee on Nomenclature and Symbols attempted to resolve this ambiguity by proposing a set of binary prefixes for the powers of 1024, including kibi (kilobinary), mebi (megabinary), and gibi (gigabinary). In December 1998, the IEC addressed such multiple usages and definitions by adopting the IUPAC's proposed prefixes (kibi, mebi, gibi, etc.) to unambiguously denote powers of 1024. Thus one kibibyte (1 KiB)
3293-483: The 100 characters are stored in @LongLink entries that would be seen as ordinary files by TAR utilities unaware of this feature. Similarly, the PAX format uses PaxHeaders entries. Many older tar implementations do not record nor restore extended attributes (xattrs) or access-control lists (ACLs). In 2001, Star introduced support for ACLs and extended attributes, through its own tags for POSIX.1-2001 pax. bsdtar uses
3382-535: The 512-byte disk sectors used in the Version 7 Unix file system.) The final block of an archive is padded out to full length with zeros. The file header record contains metadata about a file. To ensure portability across different architectures with different byte orderings , the information in the header record is encoded in ASCII . Thus if all the files in an archive are ASCII text files, and have ASCII names, then
3471-512: The Adder. The Adder may accept all or only some of the bits. Assume that it is desired to operate on 4 bit decimal digits , starting at the right. The 0-diagonal is pulsed first, sending out the six bits 0 to 5, of which the Adder accepts only the first four (0-3). Bits 4 and 5 are ignored. Next, the 4 diagonal is pulsed. This sends out bits 4 to 9, of which the last two are again ignored, and so on. It
3560-515: The IEC and ISO. An alternative system of nomenclature for the same units (referred to here as the customary convention ), in which 1 kilobyte (KB) is equal to 1,024 bytes, 1 megabyte (MB) is equal to 1024 bytes and 1 gigabyte (GB) is equal to 1024 bytes is mentioned by a 1990s JEDEC standard. Only the first three multiples (up to GB) are mentioned by the JEDEC standard, which makes no mention of TB and larger. While confusing and incorrect,
3649-410: The POSIX.1-2001 extensions that also include a vendor tag. Type '7' (Contiguous file) is formally marked as reserved in the POSIX standard, but was meant to indicate files which ought to be contiguously allocated on disk. Few operating systems support creating such files explicitly, and hence most TAR programs do not support them, and will treat type 7 files as if they were type 0 (regular). An exception
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3738-512: The Shift Matrix to be used to convert a 60-bit word , coming from Memory in parallel, into characters , or 'bytes' as we have called them, to be sent to the Adder serially. The 60 bits are dumped into magnetic cores on six different levels. Thus, if a 1 comes out of position 9, it appears in all six cores underneath. Pulsing any diagonal line will send the six bits stored along that line to
3827-478: The Stretch concepts, including the basic byte and word sizes, which are powers of 2. For economy, however, the byte size was fixed at the 8 bit maximum, and addressing at the bit level was replaced by byte addressing. Since then the term byte has generally meant 8 bits, and it has thus passed into the general vocabulary. Are there any other terms coined especially for
3916-631: The System/360 led to the ubiquitous adoption of the eight-bit storage size, while in detail the EBCDIC and ASCII encoding schemes are different. In the early 1960s, AT&T introduced digital telephony on long-distance trunk lines . These used the eight-bit μ-law encoding . This large investment promised to reduce transmission costs for eight-bit data. In Volume 1 of The Art of Computer Programming (first published in 1968), Donald Knuth uses byte in his hypothetical MIX computer to denote
4005-411: The archive is essentially an ASCII text file (containing many NUL characters ). The fields defined by the original Unix tar format are listed in the table below. The link indicator/file type table includes some modern extensions. When a field is unused it is filled with NUL bytes. The header uses 257 bytes, then is padded with NUL bytes to make it fill a 512 byte record. There is no "magic number" in
4094-591: The binary and decimal definitions of multiples of the byte have generally ended in favor of the manufacturers, with courts holding that the legal definition of gigabyte or GB is 1 GB = 1 000 000 000 (10 ) bytes (the decimal definition), rather than the binary definition (2 , i.e., 1 073 741 824 ). Specifically, the United States District Court for the Northern District of California held that "the U.S. Congress has deemed
4183-490: The byte has historically been hardware -dependent and no definitive standards existed that mandated the size. Sizes from 1 to 48 bits have been used. The six-bit character code was an often-used implementation in early encoding systems, and computers using six-bit and nine-bit bytes were common in the 1960s. These systems often had memory words of 12, 18, 24, 30, 36, 48, or 60 bits, corresponding to 2, 3, 4, 5, 6, 8, or 10 six-bit bytes, and persisted, in legacy systems, into
4272-452: The capacities of most storage media , particularly hard drives , flash -based storage, and DVDs . Operating systems that use this definition include macOS , iOS , Ubuntu , and Debian . It is also consistent with the other uses of the SI prefixes in computing, such as CPU clock speeds or measures of performance . A system of units based on powers of 2 in which 1 kibibyte (KiB)
4361-436: The checksum both ways, and treat it as good if either the signed or unsigned sum matches the included checksum. Unix filesystems support multiple links (names) for the same file. If several such files appear in a tar archive, only the first one is archived as a normal file; the rest are archived as hard links, with the "name of linked file" field set to the first one's name. On extraction, such hard links should be recreated in
4450-453: The computer field which have found their way into general dictionaries of English language? 1956 Summer: Gerrit Blaauw , Fred Brooks , Werner Buchholz , John Cocke and Jim Pomerene join the Stretch team. Lloyd Hunter provides transistor leadership. 1956 July [ sic ]: In a report Werner Buchholz lists the advantages of
4539-635: The customary convention is used by the Microsoft Windows operating system and random-access memory capacity, such as main memory and CPU cache size, and in marketing and billing by telecommunication companies, such as Vodafone , AT&T , Orange and Telstra . For storage capacity, the customary convention was used by macOS and iOS through Mac OS X 10.6 Snow Leopard and iOS 10, after which they switched to units based on powers of 10. Various computer vendors have coined terms for data of various sizes, sometimes with different sizes for
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#17327932816164628-454: The decimal definition of gigabyte to be the 'preferred' one for the purposes of 'U.S. trade and commerce' [...] The California Legislature has likewise adopted the decimal system for all 'transactions in this state. ' " Earlier lawsuits had ended in settlement with no court ruling on the question, such as a lawsuit against drive manufacturer Western Digital . Western Digital settled the challenge and added explicit disclaimers to products that
4717-508: The end of each file. Another issue with tar format is that it allows several (possibly different) files in archive to have identical paths and filenames. When extracting such archive, usually the latter version of a file overwrites the former. This can create a non-explicit (unobvious) tarbomb, which technically does not contain files with absolute paths or referring to parent directories, but still causes overwriting files outside current directory (for example, archive may contain two files with
4806-401: The file size, only 11 octal digits can be stored. This gives a maximum file size of 8 gigabytes on archived files. To overcome this limitation, in 2001 star introduced a base-256 coding that is indicated by setting the high-order bit of the leftmost byte of a numeric field. GNU-tar and BSD-tar followed this idea. Additionally, versions of tar from before the first POSIX standard from 1988 pad
4895-404: The file suffix .tar (e.g. somefile.tar ). A tar archive file contains uncompressed byte streams of the files which it contains. To achieve archive compression, a variety of compression programs are available, such as gzip , bzip2 , xz , lzip , lzma , zstd , or compress , which compress the entire tar archive. Typically, the compressed form of the archive receives a filename by appending
4984-477: The file system. Most modern tar programs read and write archives in the UStar ( Unix Standard TAR ) format, introduced by the POSIX IEEE P1003.1 standard from 1988. It introduced additional header fields. Older tar programs will ignore the extra information (possibly extracting partially named files), while newer programs will test for the presence of the "ustar" string to determine if the new format
5073-402: The format-specific compressor suffix to the archive file name. For example, a tar archive archive.tar , is named archive.tar.gz , when it is compressed by gzip. Byte The byte is a unit of digital information that most commonly consists of eight bits . Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it
5162-473: The former sense of the word, harking back to the days when bytes were not yet standardized." The development of eight-bit microprocessors in the 1970s popularized this storage size. Microprocessors such as the Intel 8080 , the direct predecessor of the 8086 , could also perform a small number of operations on the four-bit pairs in a byte, such as the decimal-add-adjust (DAA) instruction. A four-bit quantity
5251-488: The header, for file identification. Pre-POSIX.1-1988 (i.e. v7) tar header: The pre-POSIX.1-1988 Link indicator field can have the following values: Some pre-POSIX.1-1988 tar implementations indicated a directory by having a trailing slash (/) in the name. Numeric values are encoded in octal numbers using ASCII digits, with leading zeroes. For historical reasons, a final NUL or space character should also be used. Thus although there are 12 bytes reserved for storing
5340-421: The implementations below). The history of tar is a story of incompatibilities, known as the "tar wars". Most tar implementations can also read and create cpio and pax (the latter actually is a tar -format with POSIX -2001-extensions). Key implementations in order of origin: Additionally, most pax and cpio implementations can read and create multiple types of tar files. tar archive files usually have
5429-410: The information, while non-supporting ones like 7-Zip would process them as additional files. Besides creating and extracting archives, the functionality of the various archival utilities varies. For example, implementations might automatically detect the format of compressed TAR archives for extraction so the user does not have to specify it, and let the user limit adding files to those modified after
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#17327932816165518-566: The input and output. However, the LINK Computer can be equipped to edit out these gaps and to permit handling of bytes which are split between words. [...] [...] The maximum input-output byte size for serial operation will now be 8 bits, not counting any error detection and correction bits. Thus, the Exchange will operate on an 8-bit byte basis, and any input-output units with less than 8 bits per byte will leave
5607-428: The instruction. It is a deliberate respelling of bite to avoid accidental mutation to bit . Another origin of byte for bit groups smaller than a computer's word size, and in particular groups of four bits , is on record by Louis G. Dooley, who claimed he coined the term while working with Jules Schwartz and Dick Beeler on an air defense system called SAGE at MIT Lincoln Laboratory in 1956 or 1957, which
5696-418: The integral data type unsigned char must hold at least 256 different values, and is represented by at least eight bits (clause 5.2.4.2.1). Various implementations of C and C++ reserve 8, 9, 16, 32, or 36 bits for the storage of a byte. In addition, the C and C++ standards require that there are no gaps between two bytes. This means every bit in memory is part of a byte. Java's primitive data type byte
5785-465: The last, of IBM's second-generation transistorized computers to be developed). The first reference found in the files was contained in an internal memo written in June 1956 during the early days of developing Stretch . A byte was described as consisting of any number of parallel bits from one to six. Thus a byte was assumed to have a length appropriate for the occasion. Its first use
5874-455: The number of words transmitted to or from an input-output unit in response to a single input-output instruction. Block size is a structural property of an input-output unit; it may have been fixed by the design or left to be varied by the program. [...] Most important, from the point of view of editing, will be the ability to handle any characters or digits, from 1 to 6 bits long. Figure 2 shows
5963-460: The physical or logical control of data flow over the transmission media. During the early 1960s, while also active in ASCII standardization, IBM simultaneously introduced in its product line of System/360 the eight-bit Extended Binary Coded Decimal Interchange Code (EBCDIC), an expansion of their six-bit binary-coded decimal (BCDIC) representations used in earlier card punches. The prominence of
6052-458: The potential ambiguity of the term "byte". The symbol for octet, 'o', also conveniently eliminates the ambiguity in the symbol 'B' between byte and bel . The term byte was coined by Werner Buchholz in June 1956, during the early design phase for the IBM Stretch computer, which had addressing to the bit and variable field length (VFL) instructions with a byte size encoded in
6141-453: The prefix kilo as 1000 (10 ); other systems are based on powers of 2 . Nomenclature for these systems has led to confusion. Systems based on powers of 10 use standard SI prefixes ( kilo , mega , giga , ...) and their corresponding symbols (k, M, G, ...). Systems based on powers of 2, however, might use binary prefixes ( kibi , mebi , gibi , ...) and their corresponding symbols (Ki, Mi, Gi, ...) or they might use
6230-525: The prefixes K, M, and G, creating ambiguity when the prefixes M or G are used. While the difference between the decimal and binary interpretations is relatively small for the kilobyte (about 2% smaller than the kibibyte), the systems deviate increasingly as units grow larger (the relative deviation grows by 2.4% for each three orders of magnitude). For example, a power-of-10-based terabyte is about 9% smaller than power-of-2-based tebibyte. Definition of prefixes using powers of 10—in which 1 kilobyte (symbol kB)
6319-402: The same path and filename, first of which is a symlink to some location outside current directory, and second of which is a regular file; then extracting such archive on some tar implementations may cause writing to the location pointed to by the symlink). Historically, many systems have implemented tar, and many general file archivers have at least partial support for tar (often using one of
6408-402: The same term [REDACTED] This disambiguation page lists articles associated with the title TBZ . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=TBZ&oldid=973973671 " Category : Disambiguation pages Hidden categories: Short description
6497-450: The same term even within a single vendor. These terms include double word , half word , long word , quad word , slab , superword and syllable . There are also informal terms. e.g., half byte and nybble for 4 bits, octal K for 1000 8 . Contemporary computer memory has a binary architecture making a definition of memory units based on powers of 2 most practical. The use of the metric prefix kilo for binary multiples arose as
6586-409: The star extensions to support ACLs. More recent versions of GNU tar support Linux extended attributes, reimplementing star extensions. A number of extensions are reviewed in the filetype manual for BSD tar, tar(5). A tarbomb , in hacker slang , is a tar file that contains many files that extract into the working directory. Such a tar file can create problems by overwriting files of the same name in
6675-410: The tape between blocks (for the tape to physically start and stop moving). Some tape drives (and raw disks) support only fixed-length data blocks. Also, when writing to any medium such as a file system or network, it takes less time to write one large block than many small blocks. Therefore, the tar command writes data in records of many 512 B blocks. The user can specify a blocking factor, which
6764-691: The tar command was indicated for withdrawal in favor of pax command at least since 1994. Today, Unix-like operating systems usually include tools to support tar files, as well as utilities commonly used to compress them, such as xz , gzip , and bzip2 . The tar command has also been ported to the IBM i operating system. BSD-tar has been included in Microsoft Windows since Windows 10 April 2018 Update , and there are otherwise multiple third party tools available to read and write these formats on Windows. Many historic tape drives read and write variable-length data blocks , leaving significant wasted space on
6853-535: The term is unclear, but it can be found in British, Dutch, and German sources of the 1960s and 1970s, and throughout the documentation of Philips mainframe computers. The unit symbol for the byte is specified in IEC 80000-13 , IEEE 1541 and the Metric Interchange Format as the upper-case character B. In the International System of Quantities (ISQ), B is also the symbol of the bel ,
6942-724: The twenty-first century. In this era, bit groupings in the instruction stream were often referred to as syllables or slab , before the term byte became common. The modern de facto standard of eight bits, as documented in ISO/IEC 2382-1:1993, is a convenient power of two permitting the binary-encoded values 0 through 255 for one byte, as 2 to the power of 8 is 256. The international standard IEC 80000-13 codified this common meaning. Many types of applications use information representable in eight or fewer bits and processor designers commonly optimize for this usage. The popularity of major commercial computing architectures has aided in
7031-532: The ubiquitous acceptance of the 8-bit byte. Modern architectures typically use 32- or 64-bit words, built of four or eight bytes, respectively. The unit symbol for the byte was designated as the upper-case letter B by the International Electrotechnical Commission (IEC) and Institute of Electrical and Electronics Engineers (IEEE). Internationally, the unit octet explicitly defines a sequence of eight bits, eliminating
7120-425: The usable capacity may differ from the advertised capacity. Seagate was sued on similar grounds and also settled. Many programming languages define the data type byte . The C and C++ programming languages define byte as an "addressable unit of data storage large enough to hold any member of the basic character set of the execution environment" (clause 3.6 of the C standard). The C standard requires that
7209-473: The values with spaces instead of zeroes. The checksum is calculated by taking the sum of the unsigned byte values of the header record with the eight checksum bytes taken to be ASCII spaces (decimal value 32). It is stored as a six digit octal number with leading zeroes followed by a NUL and then a space. Various implementations do not adhere to this format. In addition, some historic tar implementations treated bytes as signed. Implementations typically calculate
7298-508: The working directory and, like a tarbomb, have the potential to overwrite existing files. However, modern versions of FreeBSD and GNU tar do not create or extract absolute paths and parent-directory references by default, unless it is explicitly allowed with the flag -P or the option --absolute-names . The bsdtar program, which is also available on many operating systems and is the default tar utility on Mac OS X v10.6, also does not follow parent-directory references or symbolic links. If
7387-491: The working directory, or mixing one project's files into another. It is at best an inconvenience to the user, who is obliged to identify and delete a number of files interspersed with the directory's other contents. Such behavior is considered bad etiquette on the part of the archive's creator. A related problem is the use of absolute paths or parent directory references when creating tar files. Files extracted from such archives will often be created in unusual locations outside
7476-404: Was advertised as "110 Kbyte", using the 1000 convention. Likewise, the 8-inch DEC RX01 floppy (1975) held 256 256 bytes formatted, and was advertised as "256k". Some devices were advertised using a mixture of the two definitions: most notably, floppy disks advertised as "1.44 MB" have an actual capacity of 1440 KiB , the equivalent of 1.47 MB or 1.41 MiB. In 1995,
7565-451: Was created in the early days of Unix, and despite current widespread use, many of its design features are considered dated. Other formats have been created to address the shortcomings of tar. Due to the field size , the original TAR format was unable to store file paths and names in excess of 100 characters. To overcome this problem while maintaining readability by existing TAR utilities , GNU tar stores file paths and names in excess of
7654-515: Was first introduced in the Version 7 Unix in January 1979, replacing the tp program (which in turn replaced "tap"). The file structure to store this information was standardized in POSIX .1-1988 and later POSIX.1-2001, and became a format supported by most modern file archiving systems. The tar command was abandoned in POSIX.1-2001 in favor of pax command, which was to support ustar file format;
7743-523: Was in the context of the input-output equipment of the 1950s, which handled six bits at a time. The possibility of going to 8-bit bytes was considered in August 1956 and incorporated in the design of Stretch shortly thereafter . The first published reference to the term occurred in 1959 in a paper ' Processing Data in Bits and Pieces ' by G A Blaauw , F P Brooks Jr and W Buchholz in
7832-530: Was jointly developed by Rand , MIT, and IBM. Later on, Schwartz's language JOVIAL actually used the term, but the author recalled vaguely that it was derived from AN/FSQ-31 . Early computers used a variety of four-bit binary-coded decimal (BCD) representations and the six-bit codes for printable graphic patterns common in the U.S. Army ( FIELDATA ) and Navy . These representations included alphanumeric characters and special graphical symbols. These sets were expanded in 1963 to seven bits of coding, called
7921-473: Was working on IBM's Project Stretch in the mid 1950s. His letter tells the story. Not being a regular reader of your magazine, I heard about the question in the November 1976 issue regarding the origin of the term "byte" from a colleague who knew that I had perpetrated this piece of jargon [see page 77 of November 1976 BYTE, "Olde Englishe"] . I searched my files and could not locate
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