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.nf TAR(1) USER COMMANDS TAR(1) NAME tar - tape (or other media) file archiver SYNOPSIS tar -[BcdDhiklmopRstvxzZ] [-b N] [-f F] [-T F] [ filename or regexp ... ] DESCRIPTION tar provides a way to store many files into a single archive, which can be kept in another Unix file, stored on an I/O device such as tape, floppy, cartridge, or disk, sent over a network, or piped to another program. It is useful for making backup copies, or for packaging up a set of files to move them to another system. tar has existed since Version 7 Unix with very little change. It has been proposed as the standard format for interchange of files among systems that conform to the IEEE P1003 ``Portable Operating System'' standard. This version of tar supports some of the extensions which were proposed in the P1003 draft standards, including owner and group names, and support for named pipes, fifos, con- tiguous files, and block and character devices. When reading an archive, this version of tar continues after finding an error. Previous versions required the `i' option to ignore checksum errors. OPTIONS tar options can be specified in either of two ways. The usual Unix conventions can be used: each option is preceded by `-'; arguments directly follow each option; multiple options can be combined behind one `-' as long as they take no arguments. For compatability with the Unix tar program, the options may also be specified as ``keyletters,'' wherein all the option letters occur in the first argument to tar, with no `-', and their arguments, if any, occur in the second, third, ... arguments. Examples: Normal: tar -f arcname -cv file1 file2 Old: tar fcv arcname file1 file2 At least one of the -c, -t, -d, or -x options must be included. The rest are optional. Files to be operated upon are specified by a list of file names, which follows the option specifications (or can be read from a file by the -T option). Specifying a directory name causes that directory and all the files it contains to be (recursively) processed. If a full path name is specified when creating an archive, it will be written to the archive without the initial "/", to allow the files to be later read into a different place than where they were dumped from, and a warning will be printed. If files are extracted from an archive which contains full path names, they will be extracted relative to the current directory and a warning message printed. When extracting or listing files, the ``file names'' are treated as regular expressions, using mostly the same syntax as the shell. The shell actually matches each substring between ``/''s separately, while tar matches the entire string at once, so some anomalies will occur; e.g. ``*'' or ``?'' can match a ``/''. To specify a regular expression as an argument to tar, quote it so the shell will not expand it. -b N Specify a blocking factor for the archive. The block size will be N x 512 bytes. Larger blocks typically run faster and let you fit more data on a tape. The default blocking factor is set when tar is compiled, and is typically 20. There is no limit to the maximum block size, as long as enough memory can be allocated for it, and as long as the device containing the archive can read or write that block size. -B When reading an archive, reblock it as we read it. Normally, tar reads each block with a single read(2) system call. This does not work when reading from a pipe or network socket under Berkeley Unix; read(2) only gives as much data as has arrived at the moment. With this option, it will do multiple read(2)s to fill out to a record boundary, rather than reporting an error. This option is default when reading an archive from standard input, or over a network. -c Create an archive from a list of files. -d Diff an archive against the files in the file system. Reports differences in file size, mode, uid, gid, and contents. If a file exists on the tape, but not in the file system, that is reported. This option needs further work to be really useful. -D When creating an archive, only dump each directory itself; don't dump all the files inside the directory. In conjunction with find(1), this is useful in creating incremental dumps for archival backups, similar to those produced by dump(8). -f F Specify the filename of the archive. If the specified filename is ``-'', the archive is read from the standard input or written to the standard output. If the -f option is not used, and the environment variable TAPE exists, its value will be used; otherwise, a default archive name (which was picked when tar was compiled) is used. The default is normally set to the ``first'' tape drive or other transportable I/O medium on the system. If the filename contains a colon before a slash, it is interpreted as a ``hostname:/file/name'' pair. tar will invoke the commands rsh and dd to access the specified file or device on the system hostname. If you need to do something unusual like rsh with a dif- ferent user name, use ``-f -'' and pipe it to rsh manu- ally. -h When creating an archive, if a symbolic link is encoun- tered, dump the file or directory to which it points, rather than dumping it as a symbolic link. -i When reading an archive, ignore blocks of zeros in the archive. Normally a block of zeros indicates the end of the archive, but in a damaged archive, or one which was created by appending several archives, this option allows tar to continue. It is not on by default because there is garbage written after the zeroed blocks by the Unix tar program. Note that with this option set, tar will read all the way to the end of the file, eliminating problems with multi-file tapes. -k When extracting files from an archive, keep existing files, rather than overwriting them with the version from the archive. -l When dumping the contents of a directory to an archive, stay within the local file system of that directory. This option only affects the files dumped because they are in a dumped directory; files named on the command line are always dumped, and they can be from various file systems. This is useful for making ``full dump'' archival backups of a file system, as with the dump(8) command. Files which are skipped due to this option are mentioned on the standard error. -m When extracting files from an archive, set each file's modified timestamp to the current time, rather than extracting each file's modified timestamp from the archive. -o When creating an archive, write an old format archive, which does not include information about directories, pipes, fifos, contiguous files, or device files, and specifies file ownership by uid's and gid's rather than by user names and group names. In most cases, a ``new'' format archive can be read by an ``old'' tar program without serious trouble, so this option should seldom be needed. -p When extracting files from an archive, restore them to the same permissions that they had in the archive. If -p is not specified, the current umask limits the per- missions of the extracted files. See umask(2). -R With each message that tar produces, print the record number within the archive where the message occurred. This option is especially useful when reading damaged archives, since it helps to pinpoint the damaged sec- tion. -s When specifying a list of filenames to be listed or extracted from an archive, the -s flag specifies that the list is sorted into the same order as the tape. This allows a large list to be used, even on small machines, because the entire list need not be read into memory at once. Such a sorted list can easily be created by running ``tar -t'' on the archive and edit- ing its output. -t List a table of contents of an existing archive. If file names are specified, just list files matching the specified names. The listing appears on the standard output. -T F Rather than specifying file names or regular expres- sions as arguments to the tar command, this option specifies that they should be read from the file F, one per line. If the file name specified is ``-'', the list is read from the standard input. This option, in conjunction with the -s option, allows an arbitrarily large list of files to be processed, and allows the list to be piped to tar. -v Be verbose about the files that are being processed or listed. Normally, archive creation, file extraction, and differencing are silent, and archive listing just gives file names. The -v option causes an ``ls -l''-like listing to be produced. The output from -v appears on the standard output except when creating an archive (since the new archive might be on standard output), where it goes to the standard error output. -x Extract files from an existing archive. If file names are specified, just extract files matching the speci- fied names, otherwise extract all the files in the archive. -z or -Z The archive should be compressed as it is written, or decompressed as it is read, using the compress(1) pro- gram. This option works on I/O devices and over the network, as well as on disk files; data to or from such devices is reblocked using a ``dd'' command to enforce the specified (or default) block size. The default compression parameters are used; if you need to over- ride them, avoid the ``z'' option and compress it your- self. SEE ALSO shar(1), tar(5), compress(1), ar(1), arc(1), cpio(1), dump(8), restore(8), restor(8), rsh(1), dd(1), find(1) BUGS The r, u, w, X, l, F, C, and digit options of Unix tar are not supported. Multiple-tape (or floppy) archives should be supported, but so far no clean way has been implemented. A bug in the Bourne Shell usually causes an extra newline to be written to the standard error when using compressed or remote archives. A bug in ``dd'' prevents turning off the ``x+y records in/out'' messages on the standard error when ``dd'' is used to reblock or transport an archive. TAR(5) FILE FORMATS TAR(5) NAME tar - tape (or other media) archive file format DESCRIPTION A ``tar tape'' or file contains a series of records. Each record contains TRECORDSIZE bytes (see below). Although this format may be thought of as being on magnetic tape, other media are often used. Each file archived is represented by a header record which describes the file, followed by zero or more records which give the contents of the file. At the end of the archive file there may be a record filled with binary zeros as an end-of-file indicator. A reasonable system should write a record of zeros at the end, but must not assume that an end-of-file record exists when reading an archive. The records may be blocked for physical I/O operations. Each block of N records (where N is set by the -b option to tar) is written with a single write() operation. On mag- netic tapes, the result of such a write is a single tape record. When writing an archive, the last block of records should be written at the full size, with records after the zero record containing all zeroes. When reading an archive, a reasonable system should properly handle an archive whose last block is shorter than the rest, or which contains gar- bage records after a zero record. The header record is defined in the header file <tar.h> as follows: /* * Standard Archive Format - Standard TAR - USTAR */ #define RECORDSIZE 512 #define NAMSIZ 100 #define TUNMLEN 32 #define TGNMLEN 32 union record { char charptr[RECORDSIZE]; struct header { char name[NAMSIZ]; char mode[8]; char uid[8]; char gid[8]; char size[12]; char mtime[12]; char chksum[8]; char linkflag; char linkname[NAMSIZ]; char magic[8]; char uname[TUNMLEN]; char gname[TGNMLEN]; char devmajor[8]; char devminor[8]; } header; }; /* The checksum field is filled with this while the checksum is computed. */ #define CHKBLANKS " " /* 8 blanks, no null */ /* The magic field is filled with this if uname and gname are valid. */ #define TMAGIC "ustar " /* 7 chars and a null */ /* The linkflag defines the type of file */ #define LF_OLDNORMAL '\0' /* Normal disk file, Unix compatible */ #define LF_NORMAL '0' /* Normal disk file */ #define LF_LINK '1' /* Link to previously dumped file */ #define LF_SYMLINK '2' /* Symbolic link */ #define LF_CHR '3' /* Character special file */ #define LF_BLK '4' /* Block special file */ #define LF_DIR '5' /* Directory */ #define LF_FIFO '6' /* FIFO special file */ #define LF_CONTIG '7' /* Contiguous file */ /* Further link types may be defined later. */ /* Bits used in the mode field - values in octal */ #define TSUID 04000 /* Set UID on execution */ #define TSGID 02000 /* Set GID on execution */ #define TSVTX 01000 /* Save text (sticky bit) */ /* File permissions */ #define TUREAD 00400 /* read by owner */ #define TUWRITE 00200 /* write by owner */ #define TUEXEC 00100 /* execute/search by owner */ #define TGREAD 00040 /* read by group */ #define TGWRITE 00020 /* write by group */ #define TGEXEC 00010 /* execute/search by group */ #define TOREAD 00004 /* read by other */ #define TOWRITE 00002 /* write by other */ #define TOEXEC 00001 /* execute/search by other */ All characters in header records are represented using 8-bit characters in the local variant of ASCII. Each field within the structure is contiguous; that is, there is no padding used within the structure. Each character on the archive medium is stored contiguously. Bytes representing the contents of files (after the header record of each file) are not translated in any way and are not constrained to represent characters or to be in any character set. The tar(5) format does not distinguish text files from binary files, and no translation of file contents should be performed. The fields name, linkname, magic, uname, and gname are null-terminated character strings. All other fields are zero-filled octal numbers in ASCII. Each numeric field (of width w) contains w-2 digits, a space, and a null, except size and mtime, which do not contain the trailing null. The name field is the pathname of the file, with directory names (if any) preceding the file name, separated by slashes. The mode field provides nine bits specifying file permis- sions and three bits to specify the Set UID, Set GID and Save Text (TSVTX) modes. Values for these bits are defined above. When special permissions are required to create a file with a given mode, and the user restoring files from the archive does not hold such permissions, the mode bit(s) specifying those special permissions are ignored. Modes which are not supported by the operating system restoring files from the archive will be ignored. Unsupported modes should be faked up when creating an archive; e.g. the group permission could be copied from the `other' permission. The uid and gid fields are the user and group ID of the file owners, respectively. The size field is the size of the file in bytes; linked files are archived with this field specified as zero. The mtime field is the modification time of the file at the time it was archived. It is the ASCII representation of the octal value of the last time the file was modified, represented as in integer number of seconds since January 1, 1970, 00:00 Coordinated Universal Time. The chksum field is the ASCII representaion of the octal value of the simple sum of all bytes in the header record. Each 8-bit byte in the header is treated as an unsigned value. These values are added to an unsigned integer, ini- tialized to zero, the precision of which shall be no less than seventeen bits. When calculating the checksum, the chksum field is treated as if it were all blanks. The typeflag field specifies the type of file archived. If a particular implementation does not recognize or permit the specified type, the file will be extracted as if it were a regular file. As this action occurs, tar issues a warning to the standard error. LF_NORMAL or LF_OLDNORMAL represents a regular file. For backward compatibility, a typeflag value of LF_OLDNORMAL should be silently recognized as a regular file. New archives should be created using LF_NORMAL. Also, for backward compata- bility, tar treats a regular file whose name ends with a slash as a directory. LF_LINK represents a file linked to another file, of any type, previously archived. Such files are identified in Unix by each file having the same device and inode number. The linked-to name is specified in the linkname field with a trailing null. LF_SYMLINK represents a symbolic link to another file. The linked-to name is specified in the linkname field with a trailing null. LF_CHR or LF_BLK represent character special files and block special files respectively. In this case the devmajor and dev- minor fields will contain the major and minor device numbers respectively. Operating systems may map the device specifications to their own local specification, or may ignore the entry. LF_DIR specifies a directory or sub-directory. The directory name in the name field should end with a slash. On systems where disk allocation is performed on a direc- tory basis the size field will contain the maximum number of bytes (which may be rounded to the nearest disk block allocation unit) which the directory may hold. A size field of zero indicates no such limiting. Systems which do not support limiting in this manner should ignore the size field. LF_FIFO specifies a FIFO special file. Note that the archiving of a FIFO file archives the existence of this file and not its contents. LF_CONTIG specifies a contiguous file, which is the same as a normal file except that, in operating systems which support it, all its space is allocated contiguously on the disk. Operating systems which do not allow con- tiguous allocation should silently treat this type as a normal file. `A' - `Z' are reserved for custom implementations. None are used by this version of the tar program. other values are reserved for specification in future revi- sions of the P1003 standard, and should not be used by any tar program. The magic field indicates that this archive was output in the P1003 archive format. If this field contains TMAGIC, then the uname and gname fields will contain the ASCII representation of the owner and group of the file respec- tively. If found, the user and group ID represented by these names will be used rather than the values contained within the uid and gid fields. User names longer than TUNMLEN-1 or group names longer than TGNMLEN-1 characters will be truncated. SEE ALSO tar(1), ar(5), cpio(5), dump(8), restor(8), restore(8) BUGS Names or link names longer than NAMSIZ-1 characters cannot be archived. This format does not yet address multi-volume archives. NOTES This manual page was adapted by John Gilmore from Draft 6 of the P1003 specification The README file from the source distribution follows: This is the Nov87 release of a public domain tar(1) replacement. It implements the 'c', 'x', and 't' commands of Unix tar, and many of the options. It creates P1003 "Unix Standard" [draft 6] tapes by default, and can read and write both old and new formats. It can compress or decompress tar archives "on the fly" (using the 'z' option) as well as accessing remote tape drives or files by specifying "host:/dev/tapedrive". It lets you set the default tape drive by setting TAPE in your environment. Its verbose output looks more like "ls -l" than the Unix tar, the columns line up, and you can get verbose listings from the 'cvv' option as well as from 'xvv' and 'tv'. It does shell-globbing (regular expressions) for listing and extraction. It is a little better at reading damaged tapes than Unix tar. There is a half-baked "diff" option for comparing a tape against the file system. And it's free. It is designed to be a lot more efficient than the standard Unix tar; it does as little bcopy-ing as possible, and does file I/O in large blocks. On the other hand, it has not been timed or performance-tuned; it's just *designed* to be faster. On SunOS 3.3, the tar archives it creates under the 'old' option are byte-for-byte the same as those created by /bin/tar, except the trash at the end of each file and at the end of the archive has been replaced by zeroes. It was written and initially debugged on a Sun Workstation running 4.2BSD. It has been run on Xenix, Unisoft, Vax 4.2BSD, utzoonix, USG, Masscomp, Minix, and MSDOS systems. I'm interested in finding people who will port it to other types of (Unix and non-Unix) systems, use it, and send back the changes; and people who will add the obscure tar options that they happen to use and I don't. In particular, VMS, Mac, Atari and Amiga versions would be handy. It still has a number of loose ends, marked by "FIXME" comments in the source. Fixes to these things are also welcome. I am the author of all the code in this program, except some of the subroutines, which are from contributors listed below. I hereby place it in the public domain. If you modify it, or port it to another system, please send me back a copy, so I can keep a master source. This program is much better than it started, due to the effort and care put in by Henry Spencer, Fred Fish, Ian Darwin, Geoff Collyer, Stan Barber, Guy Harris, Dave Brower, Richard Todd, Michael Rendell, Stu Heiss, and Rich $alz. Thank you, one and all. John Gilmore Nebula Consultants PO Box 170608 San Francisco, California, USA 94117-0608 hoptoad!gnu or gnu@toad.com Hoptoad talks to sun, ptsfa, ihnp4, utzoo, ucsfcgl. @(#)README 1.14 87/11/11