xar - eXtensible ARchiver
xar is no longer under active development by Apple. Clients
of xar should pursue alternative archive formats.
The XAR project aims to provide an easily extensible archive
format. Important design decisions include an easily extensible XML table of
contents (TOC) for random access to archived files, storing the TOC at the
beginning of the archive to allow for efficient handling of streamed
archives, the ability to handle files of arbitrarily large sizes, the
ability to choose independent encodings for individual files in the archive,
the ability to store checksums for individual files in both compressed and
uncompressed form, and the ability to query the table of content's rich
meta-data.
- --compression
- Specifies the compression type to use. Valid values: none, gzip, bzip2,
lzma (on some systems). Default value: gzip
- -C <path>
- On extract, xar will chdir to the specified path before extracting the
archive.
- -a
- Synonym for --compression=lzma
- -j
- Synonym for --compression=bzip2
- -z
- Synonym for --compression=gzip
- --compression-args=<arguments>
- Specifies arguments to the compression engine selected. gzip, bzip2, and
lzma all take a single integer argument between 0 and 9 specifying the
compression level to use.
- --dump-toc=<filename>
- Has xar dump the xml header into the specified file. "-" can be
specified to mean stdout.
- --dump-toc-cksum
- Dumps the ToC checksum to stdout along with the algorithm of the ToC.
- --dump-header
- Has xar print out the xar binary header information to stdout.
- Extracts the specified subdocument to a document in cwd named
<name>.xml
- --list-subdocs
- List the subdocuments in the xml header
- --toc-cksum
- Specifies the hashing algorithm to use for xml header verification. Valid
values: md5 (on some systems), sha1, sha256, and sha512. Default value:
sha1
- --file-cksum
- Specifies the hashing algorithm to use for file content verification.
Valid values: md5 (on some systems), sha1, sha256, and sha512. Default
value: sha1
- -l
- On archival, stay on the local device.
- -P
- On extract, set ownership based on uid/gid. If the uid/gid can be set on
the extracted file, setuid/setgid bits will also be preserved.
- -p
- On extract, set ownership based on symbolic names, if possible. If the
uid/gid can be set on the extracted file, setuid/setgid bits will also be
preserved.
- -s <filename>
- On extract, specifies the file to extract subdocuments to. On archival,
specifies an xml file to add as a subdocument.
- -v
- Verbose output
- --exclude
- Specifies a POSIX regular expression of files to exclude from adding to
the archive during creation or from being extracted during extraction.
This option can be specified multiple times.
- --rsize
- Specifies a size (in bytes) for the internal libxar read buffer while
performing I/O.
- --coalesce-heap
- When multiple files in the archive are identical, only store one copy of
the data in the heap. This creates smaller archives, but the archives
created are not streamable.
- --link-same
- When the data section of multiple files are identical, hardlink them
within the archive.
- --no-compress
- Specifies a POSIX regular expression of files to archive, but not
compress. The archived files will be copied raw into the archive. This can
be used to exclude already gzipped files from being gzipped during the
archival process.
- --prop-include
- Specifies a file property to be included in the archive. When this option
is specified, only the specified options will be included. Anything not
specifically included with this option will be omitted. This option can be
used multiple times.
- --prop-exclude
- Specifies a file property to be excluded from the archive. When this
option is specified, all file properties will be included except the
specified properties. This option can be used multiple times.
- --distribution
- Creates an archive to only contain file properties safe for file
distribution. Currently, only name, type, mode, and data are preserved
with this option.
- --keep-existing
- Does not overwrite existing files during extraction. Keeps any previously
existing files while extracting.
- -k
- Synonym for --keep-existing.
- --keep-setuid
- When extracting without -p or -P options, xar will extract files as the
uid/gid of the extracting process. In this situation, xar will strip
setuid/setgid bits from the extracted files for security reasons.
--keep-setuid will preserve the setuid/setgid bits even though the uid/gid
of the extracted file is not the same as the archived file.
Rob Braun <bbraun AT synack DOT net>
Landon Fuller <landonf AT bikemonkey DOT org>
David Leimbach
Kevin Van Vechten