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<p><i>ARCHIVE_WRITE_OPTIONS</i>(3) Library Functions Manual
<i>ARCHIVE_WRITE_OPTIONS</i>(3)</p>

<p style="margin-top: 1em"><b>NAME</b></p>


<p style="margin-left:9%;">archive_write_set_filter_option,
archive_write_set_format_option, archive_write_set_option,
archive_write_set_options &mdash; functions controlling
options for writing archives</p>

<p style="margin-top: 1em"><b>LIBRARY</b></p>

<p style="margin-left:9%;">Streaming Archive Library
(libarchive, -larchive)</p>

<p style="margin-top: 1em"><b>SYNOPSIS</b></p>

<p style="margin-left:9%;"><i>int</i></p>


<p><b>archive_write_set_filter_option</b>(<i>struct&nbsp;archive&nbsp;*</i>,
<i>const&nbsp;char&nbsp;*module</i>,
<i>const&nbsp;char&nbsp;*option</i>,
<i>const&nbsp;char&nbsp;*value</i>);</p>

<p style="margin-left:9%; margin-top: 1em"><i>int</i></p>


<p><b>archive_write_set_format_option</b>(<i>struct&nbsp;archive&nbsp;*</i>,
<i>const&nbsp;char&nbsp;*module</i>,
<i>const&nbsp;char&nbsp;*option</i>,
<i>const&nbsp;char&nbsp;*value</i>);</p>

<p style="margin-left:9%; margin-top: 1em"><i>int</i></p>


<p><b>archive_write_set_option</b>(<i>struct&nbsp;archive&nbsp;*</i>,
<i>const&nbsp;char&nbsp;*module</i>,
<i>const&nbsp;char&nbsp;*option</i>,
<i>const&nbsp;char&nbsp;*value</i>);</p>

<p style="margin-left:9%; margin-top: 1em"><i>int</i></p>


<p><b>archive_write_set_options</b>(<i>struct&nbsp;archive&nbsp;*</i>,
<i>const&nbsp;char&nbsp;*options</i>);</p>

<p style="margin-top: 1em"><b>DESCRIPTION</b></p>

<p style="margin-left:9%;">These functions provide a way
for libarchive clients to configure specific write
modules.</p>


<p style="margin-top: 1em"><b>archive_write_set_filter_option</b>(),
<b>archive_write_set_format_option</b>()</p>

<p style="margin-left:19%;">Specifies an option that will
be passed to the currently-registered filters (including
decompression filters) or format readers.</p>

<p style="margin-left:19%; margin-top: 1em">If
<i>option</i> and <i>value</i> are both NULL, these
functions will do nothing and <b>ARCHIVE_OK</b> will be
returned. If <i>option</i> is NULL but <i>value</i> is not,
these functions will do nothing and <b>ARCHIVE_FAILED</b>
will be returned.</p>

<p style="margin-left:19%; margin-top: 1em">If
<i>module</i> is not NULL, <i>option</i> and <i>value</i>
will be provided to the filter or reader named
<i>module</i>. The return value will be either
<b>ARCHIVE_OK</b> if the option was successfully handled or
<b>ARCHIVE_WARN</b> if the option was unrecognized by the
module or could otherwise not be handled. If there is no
such module, <b>ARCHIVE_FAILED</b> will be returned.</p>

<p style="margin-left:19%; margin-top: 1em">If
<i>module</i> is NULL, <i>option</i> and <i>value</i> will
be provided to every registered module. If any module
returns <b>ARCHIVE_FATAL</b>, this value will be returned
immediately. Otherwise, <b>ARCHIVE_OK</b> will be returned
if any module accepts the option, and <b>ARCHIVE_FAILED</b>
in all other cases.</p>


<p style="margin-top: 1em"><b>archive_write_set_option</b>()</p>

<p style="margin-left:19%;">Calls
<b>archive_write_set_format_option</b>(), then
<b>archive_write_set_filter_option</b>(). If either function
returns <b>ARCHIVE_FATAL</b>, <b>ARCHIVE_FATAL</b> will be
returned immediately. Otherwise, the greater of the two
values will be returned.</p>


<p style="margin-top: 1em"><b>archive_write_set_options</b>()</p>

<p style="margin-left:19%;"><i>options</i> is a
comma-separated list of options. If <i>options</i> is NULL
or empty, <b>ARCHIVE_OK</b> will be returned
immediately.</p>

<p style="margin-left:19%; margin-top: 1em">Individual
options have one of the following forms:</p>

<p><i>option=value</i></p>

<p style="margin-left:29%;">The option/value pair will be
provided to every module. Modules that do not accept an
option with this name will ignore it.</p>

<p><i>option</i></p>

<p style="margin-left:29%; margin-top: 1em">The option will
be provided to every module with a value of
&ldquo;1&rdquo;.</p>

<p><i>!option</i></p>

<p style="margin-left:29%;">The option will be provided to
every module with a NULL value.</p>

<p><i>module:option=value</i>, <i>module:option</i>,
<i>module:!option</i></p>

<p style="margin-left:29%;">As above, but the corresponding
option and value will be provided only to modules whose name
matches <i>module</i>.</p>

<p style="margin-top: 1em"><b>OPTIONS</b> <br>
Filter b64encode <b><br>
mode</b></p>

<p style="margin-left:29%; margin-top: 1em">The value is
interpreted as octal digits specifying the file mode.</p>

<p><b>name</b></p>

<p style="margin-left:29%; margin-top: 1em">The value
specifies the file name.</p>

<p>Filter bzip2 <b><br>
compression-level</b></p>

<p style="margin-left:29%;">The value is interpreted as a
decimal integer specifying the bzip2 compression level.
Supported values are from 1 to 9.</p>

<p>Filter gzip <b><br>
compression-level</b></p>

<p style="margin-left:29%;">The value is interpreted as a
decimal integer specifying the gzip compression level.
Supported values are from 0 to 9.</p>

<p><b>timestamp</b></p>

<p style="margin-left:29%;">Store timestamp. This is
enabled by default.</p>

<p>Filter lrzip <b><br>
compression</b>=<i>type</i></p>

<p style="margin-left:29%;">Use <i>type</i> as compression
method. Supported values are &ldquo;bzip2&rdquo;,
&ldquo;gzipi&rdquo;, &ldquo;lzo&rdquo; (ultra fast), and
&ldquo;zpaq&rdquo; (best, extremely slow).</p>

<p><b>compression-level</b></p>

<p style="margin-left:29%;">The value is interpreted as a
decimal integer specifying the lrzip compression level.
Supported values are from 1 to 9.</p>

<p>Filter lz4 <b><br>
compression-level</b></p>

<p style="margin-left:29%;">The value is interpreted as a
decimal integer specifying the lz4 compression level.
Supported values are from 0 to 9.</p>

<p><b>stream-checksum</b></p>

<p style="margin-left:29%;">Enable stream checksum. This is
enabled by default.</p>

<p><b>block-checksum</b></p>

<p style="margin-left:29%;">Enable block checksum. This is
disabled by default.</p>

<p><b>block-size</b></p>

<p style="margin-left:29%;">The value is interpreted as a
decimal integer specifying the lz4 compression block size.
Supported values are from 4 to 7 (default).</p>

<p><b>block-dependence</b></p>

<p style="margin-left:29%;">Use the previous block of the
block being compressed for a compression dictionary to
improve compression ratio. This is disabled by default.</p>

<p>Filter lzop <b><br>
compression-level</b></p>

<p style="margin-left:29%;">The value is interpreted as a
decimal integer specifying the lzop compression level.
Supported values are from 1 to 9.</p>

<p>Filter uuencode <b><br>
mode</b></p>

<p style="margin-left:29%; margin-top: 1em">The value is
interpreted as octal digits specifying the file mode.</p>

<p><b>name</b></p>

<p style="margin-left:29%; margin-top: 1em">The value
specifies the file name.</p>

<p>Filter xz <b><br>
compression-level</b></p>

<p style="margin-left:29%;">The value is interpreted as a
decimal integer specifying the compression level. Supported
values are from 0 to 9.</p>

<p><b>threads</b></p>

<p style="margin-left:29%;">The value is interpreted as a
decimal integer specifying the number of threads for
multi-threaded lzma compression. If supported, the default
value is read from <b>lzma_cputhreads</b>().</p>

<p>Filter zstd <b><br>
compression-level</b></p>

<p style="margin-left:29%;">The value is interpreted as a
decimal integer specifying the compression level. Supported
values depend on the library version, common values are from
1 to 22.</p>

<p><b>long</b></p>

<p style="margin-left:29%; margin-top: 1em">Enables long
distance matching. The value is interpreted as a decimal
integer specifying log2 window size in bytes. Values from 10
to 30 for 32 bit, or 31 for 64 bit, are supported.</p>

<p><b>threads</b></p>

<p style="margin-left:29%;">The value is interpreted as a
decimal integer specifying the number of threads for
multi-threaded zstd compression. If set to 0, zstd will
attempt to detect and use the number of active physical CPU
cores.</p>

<p>Format 7zip <b><br>
compression</b></p>

<p style="margin-left:29%;">The value is one of
&ldquo;store&rdquo;, &ldquo;copy&rdquo;,
&ldquo;deflate&rdquo;, &ldquo;bzip2&rdquo;,
&ldquo;lzma1&rdquo;, &ldquo;lzma2&rdquo;,
&ldquo;ppmd&rdquo;, or &ldquo;zstd&rdquo; to indicate how
the following entries should be compressed. The values
&ldquo;store&rdquo; and &ldquo;copy&rdquo; are synonyms.
Note that this setting is ignored for directories, symbolic
links, and other special entries.</p>

<p><b>compression-level</b></p>

<p style="margin-left:29%;">The value is interpreted as a
decimal integer specifying the compression level. Values
between 0 and 9 are supported, with the exception of bzip2
which only supports values between 1 and 9, and zstd which
may support negative values depending on the library version
and commonly used values 1 through 22. The interpretation of
the compression level depends on the chosen compression
method.</p>

<p><b>threads</b></p>

<p style="margin-left:29%;">The value is interpreted as a
decimal integer specifying the number of threads for
multi-threaded compression (for compressors like zstd that
support it). If set to 0, an attempt will be made to
discover the number of CPU cores.</p>

<p>Format bin <b><br>
hdrcharset</b></p>

<p style="margin-left:29%;">The value is used as a
character set name that will be used when translating file
names.</p>

<p>Format gnutar <b><br>
hdrcharset</b></p>

<p style="margin-left:29%;">The value is used as a
character set name that will be used when translating file,
group and user names.</p>

<p>Format iso9660 - volume metadata</p>

<p style="margin-left:19%;">These options are used to set
standard ISO9660 metadata.</p>

<p><b>abstract-file</b>=<i>filename</i></p>

<p style="margin-left:29%;">The file with the specified
name will be identified in the ISO9660 metadata as holding
the abstract for this volume. Default: none.</p>

<p><b>application-id</b>=<i>filename</i></p>

<p style="margin-left:29%;">The file with the specified
name will be identified in the ISO9660 metadata as holding
the application identifier for this volume. Default:
none.</p>

<p><b>biblio-file</b>=<i>filename</i></p>

<p style="margin-left:29%;">The file with the specified
name will be identified in the ISO9660 metadata as holding
the bibliography for this volume. Default: none.</p>

<p><b>copyright-file</b>=<i>filename</i></p>

<p style="margin-left:29%;">The file with the specified
name will be identified in the ISO9660 metadata as holding
the copyright for this volume. Default: none.</p>

<p><b>publisher</b>=<i>filename</i></p>

<p style="margin-left:29%;">The file with the specified
name will be identified in the ISO9660 metadata as holding
the publisher information for this volume. Default:
none.</p>

<p><b>volume-id</b>=<i>string</i></p>

<p style="margin-left:29%;">The specified string will be
used as the Volume Identifier in the ISO9660 metadata. It is
limited to 32 bytes. Default: none.</p>

<p>Format iso9660 - boot support</p>

<p style="margin-left:19%;">These options are used to make
an ISO9660 image that can be directly booted on various
systems.</p>

<p><b>boot</b>=<i>filename</i></p>

<p style="margin-left:29%;">The file matching this name
will be used as the El Torito boot image file.</p>

<p><b>boot-catalog</b>=<i>name</i></p>

<p style="margin-left:29%;">The name that will be used for
the El Torito boot catalog. Default: <i>boot.catalog</i></p>

<p><b>boot-info-table</b></p>

<p style="margin-left:29%;">The boot image file provided by
the <b>boot</b>=<i>filename</i> option will be edited with
appropriate boot information in bytes 8 through 64. Default:
disabled</p>

<p><b>boot-load-seg</b>=<i>hexadecimal-number</i></p>

<p style="margin-left:29%;">The load segment for a
no-emulation boot image.</p>

<p><b>boot-load-size</b>=<i>decimal-number</i></p>

<p style="margin-left:29%;">The number of
&quot;virtual&quot; 512-byte sectors to be loaded from a
no-emulation boot image. Some very old BIOSes can only load
very small images, setting this value to 4 will often allow
such BIOSes to load the first part of the boot image (which
will then need to be intelligent enough to load the rest of
itself). This should not be needed unless you are trying to
support systems with very old BIOSes. This defaults to the
full size of the image.</p>

<p><b>boot-type</b>=<i>value</i></p>

<p style="margin-left:29%;">Specifies the boot semantics
used by the El Torito boot image: If the <i>value</i> is
<b>fd</b>, then the boot image is assumed to be a bootable
floppy image. If the <i>value</i> is <b>hd</b>, then the
boot image is assumed to be a bootable hard disk image. If
the <i>value</i> is <b>no-emulation</b>, the boot image is
used without floppy or hard disk emulation. If the boot
image is exactly 1.2MB, 1.44MB, or 2.88MB, then the default
is <b>fd</b>, otherwise the default is
<b>no-emulation</b>.</p>

<p>Format iso9660 - filename and size extensions</p>

<p style="margin-left:19%;">Various extensions to the base
ISO9660 format.</p>

<p><b>allow-ldots</b></p>

<p style="margin-left:29%;">If enabled, allows filenames to
begin with a leading period. If disabled, filenames that
begin with a leading period will have that period replaced
by an underscore character in the standard ISO9660
namespace. This does not impact names stored in the
Rockridge or Joliet extension area. Default: disabled.</p>

<p><b>allow-lowercase</b></p>

<p style="margin-left:29%;">If enabled, allows filenames to
contain lowercase characters. If disabled, filenames will be
forced to uppercase. This does not impact names stored in
the Rockridge or Joliet extension area. Default:
disabled.</p>

<p><b>allow-multidot</b></p>

<p style="margin-left:29%;">If enabled, allows filenames to
contain multiple period characters, in violation of the
ISO9660 specification. If disabled, additional periods will
be converted to underscore characters. This does not impact
names stored in the Rockridge or Joliet extension area.
Default: disabled.</p>

<p><b>allow-period</b></p>

<p style="margin-left:29%;">If enabled, allows filenames to
contain trailing period characters, in violation of the
ISO9660 specification. If disabled, trailing periods will be
converted to underscore characters. This does not impact
names stored in the Rockridge or Joliet extension area.
Default: disabled.</p>

<p><b>allow-pvd-lowercase</b></p>

<p style="margin-left:29%;">If enabled, the Primary Volume
Descriptor may contain lowercase ASCII characters, in
violation of the ISO9660 specification. If disabled,
characters will be converted to uppercase ASCII. Default:
disabled.</p>

<p><b>allow-sharp-tilde</b></p>

<p style="margin-left:29%;">If enabled, sharp and tilde
characters will be permitted in filenames, in violation if
the ISO9660 specification. If disabled, such characters will
be converted to underscore characters. Default:
disabled.</p>

<p><b>allow-vernum</b></p>

<p style="margin-left:29%;">If enabled, version numbers
will be included with files. If disabled, version numbers
will be suppressed, in violation of the ISO9660 standard.
This does not impact names stored in the Rockridge or Joliet
extension area. Default: enabled.</p>

<p><b>iso-level</b></p>

<p style="margin-left:29%;">This enables support for file
size and file name extensions in the core ISO9660 area. The
name extensions specified here do not affect the names
stored in the Rockridge or Joliet extension areas.</p>

<p><b>iso-level=1</b></p>

<p style="margin-left:40%;">The most compliant form of
ISO9660 image. Filenames are limited to 8.3 uppercase
format, directory names are limited to 8 uppercase
characters, files are limited to 4 GiB, the complete ISO9660
image cannot exceed 4 GiB.</p>

<p><b>iso-level=2</b></p>

<p style="margin-left:40%;">Filenames are limited to 30
uppercase characters with a 30-character extension,
directory names are limited to 30 characters, files are
limited to 4 GiB.</p>

<p><b>iso-level=3</b></p>

<p style="margin-left:40%;">As with <b>iso-level=2</b>,
except that files may exceed 4 GiB.</p>

<p><b>iso-level=4</b></p>

<p style="margin-left:40%;">As with <b>iso-level=3</b>,
except that filenames may be up to 193 characters and may
include arbitrary 8-bit characters.</p>

<p><b>joliet</b></p>


<p style="margin-left:29%; margin-top: 1em">Microsoft&rsquo;s
Joliet extensions store a completely separate set of
directory information about each file. In particular, this
information includes Unicode filenames of up to 255
characters. Default: enabled.</p>

<p><b>limit-depth</b></p>

<p style="margin-left:29%;">If enabled, libarchive will use
directory relocation records to ensure that no pathname
exceeds the ISO9660 limit of 8 directory levels. If
disabled, no relocation will occur. Default: enabled.</p>

<p><b>limit-dirs</b></p>

<p style="margin-left:29%;">If enabled, libarchive will
cause an error if there are more than 65536 directories. If
disabled, there is no limit on the number of directories.
Default: enabled</p>

<p><b>pad</b></p>

<p style="margin-left:29%; margin-top: 1em">If enabled, 300
kiB of zero bytes will be appended to the end of the
archive. Default: enabled</p>

<p><b>relaxed-filenames</b></p>

<p style="margin-left:29%;">If enabled, all 7-bit ASCII
characters are permitted in filenames (except lowercase
characters unless <b>allow-lowercase</b> is also specified).
This violates ISO9660 standards. This does not impact names
stored in the Rockridge or Joliet extension area. Default:
disabled.</p>

<p><b>rockridge</b></p>

<p style="margin-left:29%;">The Rockridge extensions store
an additional set of POSIX-style file information with each
file, including mtime, atime, ctime, permissions, and long
filenames with arbitrary 8-bit characters. These extensions
also support symbolic links and other POSIX file types.
Default: enabled.</p>

<p>Format iso9660 - zisofs support</p>

<p style="margin-left:19%;">The zisofs extensions permit
each file to be independently compressed using a
gzip-compatible compression. This can provide significant
size savings, but requires the reading system to have
support for these extensions. These extensions are disabled
by default.</p>

<p><b>compression-level</b>=number</p>

<p style="margin-left:29%;">The compression level used by
the deflate compressor. Ranges from 0 (least effort) to 9
(most effort). Default: 6</p>

<p><b>zisofs</b></p>

<p style="margin-left:29%; margin-top: 1em">Synonym for
<b>zisofs=direct</b>.</p>

<p><b>zisofs=direct</b></p>

<p style="margin-left:29%;">Compress each file in the
archive. Unlike <b>zisofs=indirect</b>, this is handled
entirely within libarchive and does not require a separate
utility. For best results, libarchive tests each file and
will store the file uncompressed if the compression does not
actually save any space. In particular, files under 2k will
never be compressed. Note that boot image files are never
compressed.</p>

<p><b>zisofs=indirect</b></p>

<p style="margin-left:29%;">Recognizes files that have
already been compressed with the <b>mkzftree</b> utility and
sets up the necessary file metadata so that readers will
correctly identify these as zisofs-compressed files.</p>

<p><b>zisofs-exclude</b>=<i>filename</i></p>

<p style="margin-left:29%;">Specifies a filename that
should not be compressed when using <b>zisofs=direct</b>.
This option can be provided multiple times to suppress
compression on many files.</p>

<p>Format mtree <b><br>
cksum</b>, <b>device</b>, <b>flags</b>, <b>gid</b>,
<b>gname</b>, <b>indent</b>, <b>link</b>, <b>md5</b>,
<b>mode</b>, <b>nlink</b>, <b>rmd160</b>, <b>sha1</b>,
<b>sha256</b>, <b>sha384</b>, <b>sha512</b>, <b>size</b>,
<b>time</b>, <b>uid</b>, <b>uname</b></p>

<p style="margin-left:29%;">Enable a particular keyword in
the mtree output. Prefix with an exclamation mark to disable
the corresponding keyword. The default is equivalent to
&ldquo;device, flags, gid, gname, link, mode, nlink, size,
time, type, uid, uname&rdquo;.</p>

<p><b>all</b></p>

<p style="margin-left:29%; margin-top: 1em">Enables all of
the above keywords.</p>

<p><b>use-set</b></p>

<p style="margin-left:29%;">Enables generation of
<b>/set</b> lines that specify default values for the
following files and/or directories.</p>

<p><b>indent</b></p>

<p style="margin-left:29%; margin-top: 1em">XXX needs
explanation XXX</p>

<p>Format newc <b><br>
hdrcharset</b></p>

<p style="margin-left:29%;">The value is used as a
character set name that will be used when translating file
names.</p>

<p>Format odc <b><br>
hdrcharset</b></p>

<p style="margin-left:29%;">The value is used as a
character set name that will be used when translating file
names.</p>

<p>Format pwb <b><br>
hdrcharset</b></p>

<p style="margin-left:29%;">The value is used as a
character set name that will be used when translating file
names.</p>

<p>Format pax <b><br>
hdrcharset</b></p>

<p style="margin-left:29%;">The value is used as a
character set name that will be used when translating file,
group and user names. The value is one of
&ldquo;BINARY&rdquo; or &ldquo;UTF-8&rdquo;. With
&ldquo;BINARY&rdquo; there is no character conversion, with
&ldquo;UTF-8&rdquo; names are converted to UTF-8.</p>

<p><b>xattrheader</b></p>

<p style="margin-left:29%;">When storing extended
attributes, this option configures which headers should be
written. The value is one of &ldquo;all&rdquo;,
&ldquo;LIBARCHIVE&rdquo;, or &ldquo;SCHILY&rdquo;. By
default, both &ldquo;LIBARCHIVE.xattr&rdquo; and
&ldquo;SCHILY.xattr&rdquo; headers are written.</p>

<p>Format ustar <b><br>
hdrcharset</b></p>

<p style="margin-left:29%;">The value is used as a
character set name that will be used when translating file,
group and user names.</p>

<p>Format v7tar <b><br>
hdrcharset</b></p>

<p style="margin-left:29%;">The value is used as a
character set name that will be used when translating file,
group and user names.</p>

<p>Format warc <b><br>
omit-warcinfo</b></p>

<p style="margin-left:29%;">Set to &ldquo;true&rdquo; to
disable output of the warcinfo record.</p>

<p>Format xar <b><br>
checksum</b>=<i>type</i></p>

<p style="margin-left:29%;">Use <i>type</i> as file
checksum method. Supported values are &ldquo;none&rdquo;,
&ldquo;md5&rdquo;, and &ldquo;sha1&rdquo; (default).</p>

<p><b>compression</b>=<i>type</i></p>

<p style="margin-left:29%;">Use <i>type</i> as compression
method. Supported values are &ldquo;none&rdquo;,
&ldquo;bzip2&rdquo;, &ldquo;gzip&rdquo; (default),
&ldquo;lzma&rdquo; and &ldquo;xz&rdquo;.</p>

<p><b>compression_level</b></p>

<p style="margin-left:29%;">The value is a decimal integer
from 1 to 9 specifying the compression level.</p>

<p><b>toc-checksum</b>=<i>type</i></p>

<p style="margin-left:29%;">Use <i>type</i> as table of
contents checksum method. Supported values are
&ldquo;none&rdquo;, &ldquo;md5&rdquo; and &ldquo;sha1&rdquo;
(default).</p>

<p>Format zip <b><br>
compression</b></p>

<p style="margin-left:29%;">The value is either
&ldquo;store&rdquo;, &ldquo;deflate&rdquo;,
&ldquo;bzip2&rdquo;, &ldquo;lzma&rdquo;, &ldquo;xz&rdquo;,
or &ldquo;zstd&rdquo; to indicate how the following entries
should be compressed. Note that this setting is ignored for
directories, symbolic links, and other special entries.</p>

<p><b>compression-level</b></p>

<p style="margin-left:29%;">The value is interpreted as a
decimal integer specifying the compression level. Values
between 0 and 9 are supported. A compression level of 0
switches the compression method to &ldquo;store&rdquo;,
other values will enable &ldquo;deflate&rdquo;,
&ldquo;bzip2&rdquo;, &ldquo;lzma&rdquo;, or
&ldquo;zstd&rdquo; compression (in order of priority,
depending on what libraries are linked) with the given
level.</p>

<p><b>threads</b></p>

<p style="margin-left:29%;">The value is interpreted as a
decimal integer specifying the number of threads to use for
compression. It is supported only for &ldquo;xz&rdquo; or
&ldquo;zstd&rdquo; compression and ignored for any other. A
threads value of 0 is a special one requesting to detect and
use as many threads as the number of active physical CPU
cores.</p>

<p><b>encryption</b></p>

<p style="margin-left:29%;">Enable encryption using
traditional zip encryption.</p>

<p><b>encryption</b>=<i>type</i></p>

<p style="margin-left:29%;">Use <i>type</i> as encryption
type. Supported values are &ldquo;zipcrypt&rdquo;
(traditional zip encryption), &ldquo;aes128&rdquo; (WinZip
AES-128 encryption) and &ldquo;aes256&rdquo; (WinZip AES-256
encryption).</p>

<p><b>experimental</b></p>

<p style="margin-left:29%;">This boolean option enables or
disables experimental Zip features that may not be
compatible with other Zip implementations.</p>

<p><b>fakecrc32</b></p>

<p style="margin-left:29%;">This boolean option disables
CRC calculations. All CRC fields are set to zero. It should
not be used except for testing purposes.</p>

<p><b>hdrcharset</b></p>

<p style="margin-left:29%;">The value is used as a
character set name that will be used when translating file
names.</p>

<p><b>zip64</b></p>

<p style="margin-left:29%; margin-top: 1em">Zip64
extensions provide additional file size information for
entries larger than 4 GiB. They also provide extended file
offset and archive size information when archives exceed 4
GiB. By default, the Zip writer selectively enables these
extensions only as needed. In particular, if the file size
is unknown, the Zip writer will include Zip64 extensions to
guard against the possibility that the file might be larger
than 4 GiB.</p>

<p style="margin-left:29%; margin-top: 1em">Setting this
boolean option will force the writer to use Zip64 extensions
even for small files that would not otherwise require them.
This is primarily useful for testing.</p>

<p style="margin-left:29%; margin-top: 1em">Disabling this
option with <b>!zip64</b> will force the Zip writer to avoid
Zip64 extensions: It will reject files with size greater
than 4 GiB, it will reject any new entries once the total
archive size reaches 4 GiB, and it will not use Zip64
extensions for files with unknown size. In particular, this
can improve compatibility when generating archives where the
entry sizes are not known in advance.</p>

<p style="margin-top: 1em"><b>EXAMPLES</b></p>

<p style="margin-left:9%;">The following example creates an
archive write handle to create a gzip-compressed ISO9660
format image. The two options here specify that the ISO9660
archive will use <i>kernel.img</i> as the boot image for El
Torito booting, and that the gzip compressor should use the
maximum compression level.</p>

<p style="margin-left:17%; margin-top: 1em">a =
archive_write_new(); <br>
archive_write_add_filter_gzip(a); <br>
archive_write_set_format_iso9660(a); <br>
archive_write_set_options(a,
&quot;boot=kernel.img,compression=9&quot;); <br>
archive_write_open_filename(a, filename, blocksize);</p>

<p style="margin-top: 1em"><b>ERRORS</b></p>

<p style="margin-left:9%;">More detailed error codes and
textual descriptions are available from the
<b>archive_errno</b>() and <b>archive_error_string</b>()
functions.</p>

<p style="margin-top: 1em"><b>SEE ALSO</b></p>

<p style="margin-left:9%;"><i>tar</i>(1),
<i>archive_read_set_options</i>(3), <i>archive_write</i>(3),
<i>libarchive</i>(3)</p>

<p style="margin-top: 1em"><b>HISTORY</b></p>

<p style="margin-left:9%;">The <b>libarchive</b> library
first appeared in FreeBSD&nbsp;5.3.</p>

<p style="margin-top: 1em"><b>AUTHORS</b></p>

<p style="margin-left:9%;">The options support for
libarchive was originally implemented by Michihiro
NAKAJIMA.</p>

<p style="margin-top: 1em"><b>BUGS</b> Debian January 31,
2020 <i>ARCHIVE_WRITE_OPTIONS</i>(3)</p>
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