tar(1)

NAME

tar − tape file archiver

SYNOPSIS

tar key [arg...] [file | -C directory] ...

DESCRIPTION

tar saves and restores archives of files on a magnetic tape, a flexible disk, or a regular file. Its actions are controlled by the key argument. key is a string of characters containing an optional version letter, exactly one function letter, and possibly one or more function modifiers. The key string can be preceded by a hyphen (-) (as when specifying options in other HP-UX commands), but it is not necessary.

Next, an additional arg argument is required for each of the function modifiers b or f used (see below). If both b and f modifiers are specified, the order of the associated arg arguments must match the order of the modifiers.

Each file argument specifies a file being saved or restored. If file is a directory name, it refers to the files and (recursively) subdirectories contained in that directory.

The version portion of the key determines in which format tar writes the archive. tar can read either format regardless of the version. The version is specified by one of the following letters:

N Write a new (POSIX) format archive. The new format allows file names up to 256 characters in length, and correctly archives and restores the following file types: regular files, character and block special devices, links, symbolic links, directories, and FIFO special files. The new version also stores the user and group name of each file and attempts to use these names to determine the uid and gid of a file when restoring with the p function modifier. This is the new default format.

O Write an old (pre-POSIX) format archive.

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

c Create a new archive; write from the beginning of the archive instead of starting after the last file. Any previous information in the archive is overwritten.

r Add the named file to the end of the archive.

t List the names of all the files on the archive. Adding the v function modifier expands this listing to include the file modes and owner numbers. The names of all files are listed each time they occur on the tape.

u Add any named file to the archive if it is not already present or has been modified since last written on that archive.

x Extract the named file from the archive and restore it to the system. If a named file matches a directory whose contents was written to the archive, this directory is (recursively) extracted. If a named file on tape does not exist on the system, the file is created as follows:

• The user, group, and other protections are restored from the tape.

• The modification time is restored from the tape unless the m function modifier is specified.

• The file owner (uid) and group owner (gid) are normally that of the restoring process.

• The set-user-ID, set-group-ID, and sticky bits are not set automatically. The o and p function modifiers control the restoration of protection; see below for more details.

If the files exist, their modes are not changed, but the set-user-ID, set-group-ID and sticky bits are cleared. If no file argument is given, the entire content of the archive is extracted. Note that if several files with the same name are on the archive, the last one overwrites all earlier ones.

The following function modifiers can be used in addition to the function letters listed above (note that some modifiers are incompatible with some functions):

A Suppress warning messages that tar did not archive a file’s access control list. By default, tar writes a warning message for each file with optional ACL entries.

b Cause tar to use the next arg argument as the blocking factor for archive records. The default is 20; the maximum is at least 20. However, if the f - modifier is used to specify the standard input, the default blocking factor is 1.

Blocking factor is determined automatically when reading 9-track tapes (key letters x and t). [On 9-track tapes, the physical tape record length is the same as the block size. The block size is defined as the logical record size times the blocking factor (number of logical records per block).] The blocking factor must be specified when reading flexible disks and cartridge tapes if they were written with a blocking factor other than the default.

If a tar file is read using a blocking factor not equal to the blocking used when the file was written, an error may occur at the end of the file but there may or may not be an actual error in the read. To prevent this problem, a blocking factor of 1 can be used, although performance may be reduced somewhat. tar writes logical records of 512 bytes, independent of how logical records may be defined elsewhere by other programs (such as variable-length records (lines) within an ASCII text file).

f Cause tar to use the next arg argument as the name of the archive instead of /dev/rmt/0m. If the name of the file is -, tar writes to the standard output or reads from the standard input, whichever is appropriate, and the default blocking factor becomes 1. Thus, tar can be used as the head or tail of a pipeline. tar can also be used to move hierarchies with the command:

cdfromdir; tar cf - . | (cd todir ; tar xf -)

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

H Cause all entries in hidden directories (context-dependent files) to be written to the archive (see cdf(4)). Normally, tar only writes the entry in the CDF that matches the context of the tar process. See getcontext(2). This modifier works only when writing archives. When reading archives, tar automatically restores hidden directories if the archive was created with the H modifier.

l Tell tar to complain if it cannot resolve all of the links to the files being saved. If l is not specified, no error messages are printed.

m Tell tar not to restore the modification time written on the archive. The modification time of the file will be the time of extraction.

o Suppress writing certain directory information that older versions of tar cannot handle on input. tar normally writes information specifying owners and modes of directories in the archive. Earlier versions of tar, when encountering this information, give error messages of the form:

name/: cannot create.

This function modifier suppresses writing that information.

When o is used for reading, it causes the extracted file to take on the user and group ID (uid and gid) of the user running the program rather than those of the tape. This is the default for the ordinary user and can be overridden, to the extent that system protections allow, by using the p function modifier.

p Cause file to be restored to the original modes and ownerships written on the archive, if possible. This is the default for the superuser, and can be overridden by the o function modifier. If system protections prevent the ordinary user from executing chown(), the error is ignored, and the ownership is set to that of the restoring process (see chown(2)). Set-user- ID, set-group- ID, and sticky bit information are restored as allowed by the protections defined by chmod() if the chown operation above succeeds.

# d Specify a particular tape drive and density where # is a tape drive number (0,...,7), and d is the density: (l = low (800 bpi), m = medium (1600 bpi), or h = high (6250 bpi)). This modifier selects the drive on which the nine-track tape is mounted. The default is 0m.

v Normally, tar does its work silently. The v (verbose) function modifier causes tar to type the name of each file it treats, preceded by the function letter. With the t function, v gives more information about the tape entries than just the name.

V Same as the v function modifier except that when using the t option, tar also prints out a letter indicating the type of the archived file.

w Cause tar to print the action being taken, followed by the name of the file, then wait for the user’s confirmation. If the user answers y, the action is performed. Any other input means “no”.

The following option can be included in the file list:

-Cdirectory tar performs a chdir() to directory (see chdir(2)). This allows multiple directories not related by a close or common parent to be archived using short relative path names.

When end-of-tape is reached, tar prompts the user for a new special file and continues.

If a nine-track tape drive is used as the output device, it must be configured in Berkeley-compatibility mode (see mt(7)).

EXTERNAL INFLUENCES

Environment Variables

LC_TIME determines the format and contents of date and time strings output when listing the contents of an archive with the -v option.

LANG determines the language equivalent of y (for yes/no queries).

If LC_TIME is not specified in the environment or is set to the empty string, the value of LANG is used as a default for each unspecified or empty variable. If LANG is not specified or is set to the empty string, a default of "C" (see lang(5)) is used instead of LANG. If any internationalization variable contains an invalid setting, tar behaves as if all internationalization variables are set to "C". See environ(5).

International Code Set Support

Single- and multi-byte character code sets are supported.

ERRORS

tar complains about bad key characters and tape read/write errors.

tar complains if not enough memory is available to hold the link tables.

EXAMPLES

Create a new archive on /dev/rfd.0 and copies file1 and file2 onto it, using the default blocking factor of 20. The key is made up of one function letter (c) and two function modifiers (v, and f):

tar cvf /dev/rfd.0 file1 file2

Archive files from /usr/include and /etc:

tar cv -C /usr/include -C /etc

WARNINGS

The default version has changed from O to N beginning with HP-UX Release 8.0.

Due to internal limitations in the header structure, not all file names of fewer than 256 characters fit when using the N version key. If a file name does not fit, tar prints a message and does not archive the file.

Link names are still limited to 100 characters when using the N version key.

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

Tape errors are handled ungracefully.

The u function key can be slow.

If the archive is on a flexible disk or cartridge tape, and if the blocking factor specified on output is not the default, the same blocking factor must be specified on input. This is because the blocking factor is not explicitly stored on the archive. Updating the archive without following this rule can destroy it.

Some previous versions of tar have claimed to support selective listing of file names using the t function key with a list. This appears to be an error in the documentation because the capability does not appear in the original source code.

There is no way to restore an absolute path name to a relative position.

tar always pads information written to an archive up to the next multiple of the block size. Therefore, if you are creating a small archive and write out one block of information, tar reports that one block was written, but the actual size of the archive might be larger if the b function modifier is used.

Note that tar c0m is not the same as tar cm0.

Do not create archives on block special devices. Attempting to do so can causes excessive wear, leading to premature drive hardware failure.

Access Control Lists

Access control list descriptions in this entry apply only to standard HP-UX operating systems. If HP-UX BLS software has been installed, access control lists are handled differently. Refer to HP-UX BLS documentation for information about access control lists in the HP-UX BLS environment.

AUTHOR

tar was developed by AT&T, the University of California, Berkeley, HP and POSIX.

FILES

/dev/rmt/*
/dev/rfd.*
/tmp/tar*

DEPENDENCIES

Series 700/800

The -r and -u options are not supported on QIC devices. If these options are used with QIC devices, tar fails and displays the message:

tar: option not supported for QIC devices

STANDARDS CONFORMANCE

tar: SVID2, XPG2, XPG3

Hewlett-Packard Company — HP-UX Release 9.0: August 1992

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