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56ba3c78ae
man rules were repeating the same information in too many places, which was error prone. Those rules can be easily generated from .xml files. For efficiency and because python is not a required dependency, Makefile-man.am is only regenerated when requested with make update-man-list If no metadata in man/*.xml changed, this file should not change. So only when a new man page or a new alias is added, this file should show up in 'git diff'. The change should then be committed. If the support for building from git without python was dropped, we could drop Makefile-man.am from version control. This would also increase the partial build time (since more stuff would be rebuild whenever sources in man/*.xml would be modified), so it would probably wouldn't be worth it.
315 lines
15 KiB
XML
315 lines
15 KiB
XML
<?xml version="1.0"?>
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<!--*-nxml-*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!--
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This file is part of systemd.
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Copyright 2012 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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This is based on crypttab(5) from Fedora's initscripts package, which in
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turn is based on Debian's version.
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The Red Hat version has been written by Miloslav Trmac <mitr@redhat.com>.
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-->
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<refentry id="crypttab" conditional='HAVE_LIBCRYPTSETUP'>
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<refentryinfo>
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<title>crypttab</title>
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<productname>systemd</productname>
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<authorgroup>
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<author>
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<contrib>Documentation</contrib>
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<firstname>Miloslav</firstname>
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<surname>Trmac</surname>
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<email>mitr@redhat.com</email>
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</author>
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<author>
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<contrib>Documentation</contrib>
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<firstname>Lennart</firstname>
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<surname>Poettering</surname>
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<email>lennart@poettering.net</email>
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</author>
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</authorgroup>
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</refentryinfo>
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<refmeta>
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<refentrytitle>crypttab</refentrytitle>
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<manvolnum>5</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>crypttab</refname>
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<refpurpose>Configuration for encrypted block devices</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<para><filename>/etc/crypttab</filename></para>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para>The <filename>/etc/crypttab</filename> file
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describes encrypted block devices that are set up
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during system boot.</para>
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<para>Empty lines and lines starting with the #
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character are ignored. Each of the remaining lines
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describes one encrypted block device, fields on the
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line are delimited by white space. The first two
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fields are mandatory, the remaining two are
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optional.</para>
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<para>The first field contains the name of the
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resulting encrypted block device; the device is set up
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within <filename>/dev/mapper/</filename>.</para>
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<para>The second field contains a path to the
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underlying block device, or a specification of a block
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device via <literal>UUID=</literal> followed by the
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UUID. If the block device contains a LUKS signature,
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it is opened as a LUKS encrypted partition; otherwise
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it is assumed to be a raw dm-crypt partition.</para>
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<para>The third field specifies the encryption
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password. If the field is not present or the password
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is set to none, the password has to be manually
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entered during system boot. Otherwise the field is
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interpreted as a path to a file containing the
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encryption password. For swap encryption
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<filename>/dev/urandom</filename> or the hardware
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device <filename>/dev/hw_random</filename> can be used
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as the password file; using
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<filename>/dev/random</filename> may prevent boot
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completion if the system does not have enough entropy
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to generate a truly random encryption key.</para>
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<para>The fourth field, if present, is a
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comma-delimited list of options. The following
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options are recognized:</para>
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<variablelist class='crypttab-options'>
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<varlistentry>
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<term><varname>cipher=</varname></term>
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<listitem><para>Specifies the cipher
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to use; see
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<citerefentry><refentrytitle>cryptsetup</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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for possible values and the default
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value of this option. A cipher with
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unpredictable IV values, such as
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<literal>aes-cbc-essiv:sha256</literal>,
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is recommended. </para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>size=</varname></term>
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<listitem><para>Specifies the key size
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in bits; see
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<citerefentry><refentrytitle>cryptsetup</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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for possible values and the default
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value of this
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option. </para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>keyfile-size=</varname></term>
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<listitem><para>Specifies the maximum number
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of bytes to read from the keyfile; see
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<citerefentry><refentrytitle>cryptsetup</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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for possible values and the default
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value of this option. This option is ignored
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in plain encryption mode, as the keyfile-size is then given by the key size.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>keyfile-offset=</varname></term>
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<listitem><para>Specifies the number
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of bytes to skip at the start of
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the keyfile; see
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<citerefentry><refentrytitle>cryptsetup</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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for possible values and the default
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value of this option.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>hash=</varname></term>
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<listitem><para>Specifies the hash to
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use for password hashing; see
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<citerefentry><refentrytitle>cryptsetup</refentrytitle><manvolnum>8</manvolnum></citerefentry> for possible values and
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the default value of this
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option. </para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>tries=</varname></term>
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<listitem><para>Specifies the maximum
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number of times the user is queried
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for a password.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>verify</varname></term>
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<listitem><para> If the encryption
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password is read from console, it has
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to be entered twice (to prevent
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typos). </para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>read-only</varname></term><term><varname>readonly</varname></term>
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<listitem><para>Set up the encrypted
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block device in read-only
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mode.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>allow-discards</varname></term>
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<listitem><para>Allow discard requests
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to be passed through the encrypted
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block device. This improves
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performance on SSD storage but has
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security
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implications.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>luks</varname></term>
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<listitem><para>Force LUKS mode.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>plain</varname></term>
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<listitem><para>Force plain encryption
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mode.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>timeout=</varname></term>
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<listitem><para>Specify the timeout
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for querying for a password. If no
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unit is specified seconds is used.
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Supported units are s, ms,
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us, min, h, d. A timeout of 0 waits
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indefinitely.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>noauto</varname></term>
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<listitem><para> This device will not
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be automatically unlocked on
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boot. </para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>nofail</varname></term>
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<listitem><para>The system will not
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wait for the device to show up and be
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unlocked at boot, and not fail the
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boot if it doesn't show
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up.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>swap</varname></term>
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<listitem><para> The encrypted block
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device will be used as a swap
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partition, and will be formatted as a
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swap partition after setting up the
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encrypted block device, with
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<citerefentry><refentrytitle>mkswap</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
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<para>WARNING: Using the
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<varname>swap</varname> option will
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destroy the contents of the named
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partition during every boot, so make
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sure the underlying block device is
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specified
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correctly. </para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>tmp</varname></term>
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<listitem><para>The encrypted block
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device will be prepared for using it
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as <filename>/tmp</filename>
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partition: it will be formatted using
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<citerefentry><refentrytitle>mke2fs</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
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<para>WARNING: Using the
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<varname>tmp</varname> option will
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destroy the contents of the named
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partition during every boot, so make
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sure the underlying block device is
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specified
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correctly. </para></listitem>
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</varlistentry>
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</variablelist>
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<para>At early boot and when the system manager
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configuration is reloaded this file is translated into
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native systemd units
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by <citerefentry><refentrytitle>systemd-cryptsetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
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</refsect1>
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<refsect1>
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<title>Example</title>
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<example>
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<title>/etc/crypttab example</title>
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<para>Set up two encrypted block devices with
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LUKS: one normal one for storage, and another
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one for usage as swap device.</para>
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<programlisting>luks-2505567a-9e27-4efe-a4d5-15ad146c258b UUID=2505567a-9e27-4efe-a4d5-15ad146c258b - timeout=0
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swap /dev/sda7 /dev/urandom swap</programlisting>
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</example>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<para>
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd-cryptsetup@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd-cryptsetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>cryptsetup</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>mkswap</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>mke2fs</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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