tar(1)

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | OPERANDS | USAGE | EXAMPLES | ENVIRONMENT VARIABLES | EXIT STATUS | FILES | ATTRIBUTES | SEE ALSO | DIAGNOSTICS | NOTES

NAME

tar- create tape archives and add or extract files

SYNOPSIS

tar c [bBeEfFhiklnopPqvwX[0-7]] [block] [tarfile] [exclude-file] {-I include-file| -C directory| file| file...}
tar r [bBeEfFhiklnqvw[0-7]] [block] {-I include-file| -C directory| file| file...}
tar t [BefFhiklnqvX[0-7]] [tarfile] [exclude-file] {-I include-file| file...}
tar u [bBeEfFhiklnqvw[0-7]] [block] [tarfile] file...
tar x [BefFhiklmnopqvwX[0-7]] [tarfile] [exclude-file] [file...]

DESCRIPTION

The tar command archives and extracts files to and from a single file called a tarfile. A tarfile is usually a magnetic tape, but it can be any file. tar's actions are controlled by the key argument. The key is a string of characters containing exactly one function letter (c, r, t , u, or x) and zero or more function modifiers (letters or digits), depending on the function letter used. The key string contains no SPACE characters. Function modifier arguments are listed on the command line in the same order as their corresponding function modifiers appear in the key string.

The -I include-file, -C directory file, and file arguments specify which files or directories are to be archived or extracted. In all cases, appearance of a directory name refers to the files and (recursively) subdirectories of that directory. Arguments appearing within braces ({ }) indicate that one of the arguments must be specified.

OPTIONS

The following options are supported:

-I include-file

Opens include-file containing a list of files, one per line, and treats it as if each file appeared separately on the command line. Be careful of trailing white spaces. Also beware of leading white spaces, since, for each line in the included file, the entire line (apart from the newline) will be used to match against the initial string of files to include. In the case where excluded files (see X function modifier) are also specified, they take precedence over all included files. If a file is specified in both the exclude-file and the include-file (or on the command line), it will be excluded.

-C directory file

Performs a chdir (see cd(1)) operation on directory and performs the c (create) or r (replace) operation on file. Use short relative path names for file. If file is `.', archive all files in directory. This option enables archiving files from multiple directories not related by a close common parent.

OPERANDS

The following operands are supported:

file

A path name of a regular file or directory to be archived (when the c, r or u functions are specified), extracted (x) or listed (t). When file is the path name of a directory, the action applies to all of the files and (recursively) subdirectories of that directory.

When a file is archived, and the E flag (see Function Modifiers) is not specified, the filename cannot exceed 256 characters. In addition, it must be possible to split the name between parent directory names so that the prefix is no longer than 155 characters and the name is no longer than 100 characters. If E is specified, a name of up to PATH_MAX characters may be specified.

For example, a file whose basename is longer than 100 characters could not be archived without using the E flag. A file whose directory portion is 200 characters and whose basename is 50 characters could be archived (without using E) if a slash appears in the directory name somewhere in character positions 151-156.

Function Letters

The function portion of the key is specified by one of the following letters:

c

Create. Writing begins at the beginning of the tarfile, instead of at the end.

r

Replace. The named files are written at the end of the tarfile. A file created with extended headers must be updated with extended headers (see E flag under Function Modifiers). A file created without extended headers cannot be modified with extended headers.

t

Table of Contents. The names of the specified files are listed each time they occur in the tarfile. If no file argument is given, the names of all files in the tarfile are listed. With the v function modifier, additional information for the specified files is displayed.

u

Update. The named files are written at the end of the tarfile if they are not already in the tarfile, or if they have been modified since last written to that tarfile. An update can be rather slow. A tarfile created on a 5.x system cannot be updated on a 4.x system. A file created with extended headers must be updated with extended headers (see E flag under Function Modifiers). A file created without extended headers cannot be modified with extended headers.

x

Extract or restore. The named files are extracted from the tarfile and written to the directory specified in the tarfile, relative to the current directory. Use the relative path names of files and directories to be extracted. If a named file matches a directory whose contents has been written to the tarfile, this directory is recursively extracted. The owner, modification time, and mode are restored (if possible); otherwise, to restore owner, you must be the super-user. Character-special and block-special devices (created by mknod(1M)) can only be extracted by the super-user. If no file argument is given, the entire content of the tarfile is extracted. If the tarfile contains several files with the same name, each file is written to the appropriate directory, overwriting the previous one. Filename substitution wildcards cannot be used for extracting files from the archive; rather, use a command of the form:

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tar xvf . . . /dev/rmt/0 `tar tf . . . /dev/rmt/0 | grep 'pattern' `

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When extracting tapes created with the r or u functions, directory modification times may not be set correctly. These same functions cannot be used with many tape drives due to tape drive limitations such as the absence of backspace or append capabilities.

When using the r, u, or x functions or the X function modifier, the named files must match exactly the corresponding files in the tarfile. For example, to extract ./thisfile, you must specify ./thisfile, and not thisfile. The t function displays how each file was archived.

Function Modifiers

The characters below may be used in conjunction with the letter that selects the desired function.

b

Blocking Factor. Use when reading or writing to raw magnetic archives (see f below). The block argument specifies the number of 512-byte tape blocks to be included in each read or write operation performed on the tarfile. The minimum is 1, the default is 20. The maximum value is a function of the amount of memory available and the blocking requirements of the specific tape device involved (see mtio(7I) for details.) The maximum cannot exceed INT_MAX/512 (4194303).

When a tape archive is being read, its actual blocking factor will be automatically detected, provided that it is less than or equal to the nominal blocking factor (the value of the block argument, or the default value if the b modifier is not specified). If the actual blocking factor is greater than the nominal blocking factor, a read error will result. See Example 5 in EXAMPLES.

B

Block. Force tar to perform multiple reads (if necessary) to read exactly enough bytes to fill a block. This function modifier enables tar to work across the Ethernet, since pipes and sockets return partial blocks even when more data is coming. When reading from standard input, '-', this function modifier is selected by default to ensure that tar can recover from short reads.

e

Error. Exit immediately with a positive exit status if any unexpected errors occur. The SYSV3 environment variable overrides the default behavior. (See ENVIRONMENT section below.)

E

Write a tarfile with extended headers. (Used with c, r, or u options; ignored with t or x options.) When a tarfile is written with extended headers, the modification time is maintained with a granularity of microseconds rather than seconds. In addition, filenames no longer than PATH_MAX characters that could not be archived without E, and file sizes greater than 8GB, are supported. The E flag is required whenever the larger files and/or files with longer names, or whose UID/GID exceed 2097151, are to be archived, or if time granularity of microseconds is desired.

f

File. Use the tarfile argument as the name of the tarfile. If f is specified, /etc/default/tar is not searched. If f is omitted, tar will use the device indicated by the TAPE environment variable, if set; otherwise, it will use the default values defined in /etc/default/tar. If the name of the tarfile is '-', tar writes to the standard output or reads from the standard input, whichever is appropriate. tar can be used as the head or tail of a pipeline. tar can also be used to move hierarchies with the command:

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example% cd fromdir; tar cf - .| (cd todir; tar xfBp -)

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F

With one F argument, tar excludes all directories named SCCS and RCS from the tarfile. With two arguments, FF, tar excludes all directories named SCCS and RCS, all files with .o as their suffix, and all files named errs, core, and a.out. The SYSV3 environment variable overrides the default behavior. (See ENVIRONMENT section below.)

h

Follow symbolic links as if they were normal files or directories. Normally, tar does not follow symbolic links.

i

Ignore directory checksum errors.

k size

Requires tar to use the size argument as the size of an archive in kilobytes. This is useful when the archive is intended for a fixed size device such as floppy disks. Large files are then split across volumes if they do not fit in the specified size.

l

Link. Output error message if unable to resolve all links to the files being archived. If l is not specified, no error messages are printed.

m

Modify. The modification time of the file is the time of extraction. This function modifier is valid only with the x function.

n

The file being read is a non-tape device. Reading of the archive is faster since tar can randomly seek around the archive.

o

Ownership. Assign to extracted files the user and group identifiers of the user running the program, rather than those on tarfile. This is the default behavior for users other than root. If the o function modifier is not set and the user is root, the extracted files will take on the group and user identifiers of the files on tarfile (see chown(1) for more information). The o function modifier is only valid with the x function.

p

Restore the named files to their original modes, and ACLs if applicable, ignoring the present umask(1). This is the default behavior if invoked as super-user with the x function letter specified. If super-user, SETUID and sticky information are also extracted, and files are restored with their original owners and permissions, rather than owned by root. When this function modifier is used with the c function, ACLs are created in the tarfile along with other information. Errors will occur when a tarfile with ACLs is extracted by previous versions of tar.

P

Suppress the addition of a trailing "/" on directory entries in the archive.

q

Stop after extracting the first occurrence of the named file. tar will normally continue reading the archive after finding an occurrence of a file.

v

Verbose. Output the name of each file preceded by the function letter. With the t function, v provides additional information about the tarfile entries. The listing is similar to the format produced by the -l option of the ls(1) command.

w

What. Output the action to be taken and the name of the file, then await the user's confirmation. If the response is affirmative, the action is performed; otherwise, the action is not performed. This function modifier cannot be used with the t function.

X

Exclude. Use the exclude-file argument as a file containing a list of relative path names for files (or directories) to be excluded from the tarfile when using the functions c, x, or t. Be careful of trailing white spaces. Also beware of leading white spaces, since, for each line in the excluded file, the entire line (apart from the newline) will be used to match against the initial string of files to exclude. Multiple X arguments may be used, with one exclude-file per argument. In the case where included files (see -I include-file option) are also specified, the excluded files take precedence over all included files. If a file is specified in both the exclude-file and the include-file (or on the command line), it will be excluded.

[0-7]

Select an alternative drive on which the tape is mounted. The default entries are specified in /etc/default/tar. If no digit or f function modifier is specified, the entry in /etc/default/tar with digit "0" is the default.

USAGE

See largefile(5) for the description of the behavior of tar when encountering files greater than or equal to 2 Gbyte ( 2³¹ bytes).

The automatic determination of the actual blocking factor may be fooled when reading from a pipe or a socket (see the B function modifier below).

1/4" streaming tape has an inherent blocking factor of one 512-byte block. It can be read or written using any blocking factor.

This function modifier works for archives on disk files and block special devices, among others, but is intended principally for tape devices.

For information on tar header format, see archives(4).

EXAMPLES

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Example 1 Using the tar Command to Create an Archive of Your Home Directory




The following is an example using tar to create an archive of your home directory on a tape mounted on drive /dev/rmt/0:

example% cd example% tar cvf /dev/rmt/0 . messages from tar

The c function letter means create the archive; the v function modifier outputs messages explaining what tar is doing; the f function modifier indicates that the tarfile is being specified ( /dev/rmt/0 in this example). The dot (.) at the end of the command line indicates the current directory and is the argument of the f function modifier.

Display the table of contents of the tarfile with the following command:

example% tar tvf /dev/rmt/0

The output will be similar to the following for the POSIX locale:

rw-r--r-- 1677/40 2123 Nov 7 18:15 1985 ./test.c . . . example%

The columns have the following meanings:

• column 1 is the access permissions to ./test.c

• column 2 is the user-id/group-id of ./test.c

• column 3 is the size of ./test.c in bytes

• column 4 is the modification date of ./test.c. When the LC_TIME category is not set to the POSIX locale, a different format and date order field may be used.

• column 5 is the name of ./test.c

To extract files from the archive:

example% tar xvf /dev/rmt/0 messages from tar example%

If there are multiple archive files on a tape, each is separated from the following one by an EOF marker. To have tar read the first and second archives from a tape with multiple archives on it, the non-rewinding version of the tape device name must be used with the f function modifier, as follows:

example% tar xvfp /dev/rmt/0n read first archive from tape messages from tar example% tar xvfp /dev/rmt/0n read second archive from tape messages from tar example%

Note that in some earlier releases, the above scenario did not work correctly, and intervention with mt(1) between tar invocations was necessary. To emulate the old behavior, use the non-rewind device name containing the letter b for BSD behavior. See the Close Operations section of the mtio(7I) manual page.

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Example 2 Using Tar To Archive Files From /usr/include And From /etc To Default Tape Drive 0:




To archive files from /usr/include and from /etc to default tape drive 0:

example% tar c -C /usr include -C /etc .

The table of contents from the resulting tarfile would produce output like the following:

include/ include/a.out.h and all the other files in /usr/include . . . ./chown and all the other files in /etc

To extract all files in the include directory:

example% tar xv include x include/, 0 bytes, 0 tape blocksand all files under include . . .

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Example 3 Using tar to Transfer Files Across the Network




The following is an example using tar to transfer files across the network. First, here is how to archive files from the local machine ( example) to a tape on a remote system ( host):

example% tar cvfb - 20 files | rsh host dd of=/dev/rmt/0 obs=20b messages from tar example%

In the example above, we are creating a tarfile with the c key letter, asking for verbose output from tar with the v function modifier, specifying the name of the output tarfile using the f function modifier (the standard output is where the tarfile appears, as indicated by the `-' sign), and specifying the blocksize (20) with the b function modifier. If you want to change the blocksize, you must change the blocksize arguments both on the tar command and on the dd command.

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Example 4 Using Tar To Retrieve Files From A Tape On The Remote System Back To The Local System:




The following is an example that uses tar to retrieve files from a tape on the remote system back to the local system:

example% rsh -n host dd if=/dev/rmt/0 bs=20b | tar xvBfb - 20 files messages from tar example%

In the example above, we are extracting from the tarfile with the x key letter, asking for verbose output from tar with the v function modifier, telling tar it is reading from a pipe with the B function modifier, specifying the name of the input tarfile using the f function modifier (the standard input is where the tarfile appears, as indicated by the `-' sign), and specifying the blocksize (20) with the b function modifier.

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Example 5 Creating An Archive Of The Home Directory On /dev/rmt/0 With ABlocking Factor Of 19




The following example creates an archive of the home directory on /dev/rmt/0 with an actual blocking factor of 19:

example% tar cvfb /dev/rmt/0 19 $HOME

To recognize this archive's actual blocking factor without using the b function modifier:

example% tar tvf /dev/rmt/0 tar: blocksize = 19 . . .

To recognize this archive's actual blocking factor using a larger nominal blocking factor:

example% tar tvf /dev/rmt/0 30 tar: blocksize = 19 . . .

Attempt to recognize this archive's actual blocking factor using a nominal blocking factor that is too small:

example% tar tvf /dev/rmt/0 10 tar: tape read error

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ENVIRONMENT VARIABLES

SYSV3

This variable is used to override the default behavior of tar, provide compatibility with INTERACTIVE UNIX Systems and SCO UNIX installation scripts, and should not be used in new scripts. (It is intended for compatibility purposes only.) When set, the following options behave differently:

-F filename

Uses filename to obtain a list of command line switches and files on which to operate.

-e

Prevents files from being split across volumes. If there is insufficient room on one volume, tar prompts for a new volume. If the file will not fix on the new volume, tar exits with an error.

See environ(5) for descriptions of the following environment variables that affect the execution of tar: LC_CTYPE, LC_MESSAGES, LC_TIME, TZ, and NLSPATH.

EXIT STATUS

The following exit values are returned:

0

Successful completion.

>0

An error occurred.

FILES

/dev/rmt/[0-7][b][n]

/dev/rmt/[0-7]l[b][n]

/dev/rmt/[0-7]m[b][n]

/dev/rmt/[0-7]h[b][n]

/dev/rmt/[0-7]u[b][n]

/dev/rmt/[0-7]c[b][n]

/etc/default/tar

Settings may look like this:

• archive0=/dev/rmt/0
• archive1=/dev/rmt/0n
• archive2=/dev/rmt/1
• archive3=/dev/rmt/1n
• archive4=/dev/rmt/0
• archive5=/dev/rmt/0n
• archive6=/dev/rmt/1
• archive7=/dev/rmt/1n

/tmp/tar*

ATTRIBUTES

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPE	ATTRIBUTE VALUE
Availability	SUNWcsu
CSI	Enabled

SEE ALSO

ar(1), basename(1), cd(1), chown(1), cpio(1), csh(1), dirname(1), ls(1), mt(1), pax(1), setfacl(1), umask(1), mknod(1M), vold(1M), archives(4), attributes(5), environ(5), largefile(5), mtio(7I)

DIAGNOSTICS

Diagnostic messages are output for bad key characters and tape read/write errors, and for insufficient memory to hold the link tables.

NOTES

There is no way to access the n-th occurrence of a file.

Tape errors are handled ungracefully.

When the Volume Management daemon is running, accesses to floppy devices through the conventional device names (for example, /dev/rdiskette) may not succeed. See vold(1M) for further details.

The tar archive format allows UIDs and GIDs up to 2097151 to be stored in the archive header. Files with UIDs and GIDs greater than this value will be archived with the UID and GID of 60001.

If an archive is created that contains files whose names were created by processes running in multiple locales, a single locale that uses a full 8-bit codeset (for example, the en_US locale) should be used both to create the archive and to extract files from the archive.

SunOS 5.8  Last Revised 28 Jan 1998

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | OPERANDS | USAGE | EXAMPLES | ENVIRONMENT VARIABLES | EXIT STATUS | FILES | ATTRIBUTES | SEE ALSO | DIAGNOSTICS | NOTES