man: Document the crypttab keyfile syntax specifying a device

Feature introduced in 50d2eba27b. Also documented
as part of the kernel parameter syntax in systemd-cryptsetup-generator(8), but
should also be documented here as part of the overall file syntax.
This commit is contained in:
Vladimir Panteleev 2020-06-12 10:44:57 +00:00 committed by Zbigniew Jędrzejewski-Szmek
parent 550c14fedd
commit f1a20afacd

View File

@ -60,13 +60,15 @@
device or file, or a specification of a block device via
<literal>UUID=</literal> followed by the UUID.</para>
<para>The third field specifies an absolute path to a file to read the encryption key from. If the field
is not present or set to <literal>none</literal> or <literal>-</literal>, a key file named after the
volume to unlock (i.e. the first column of the line), suffixed with <filename>.key</filename> is
automatically loaded from the <filename>/etc/cryptsetup-keys.d/</filename> and
<filename>/run/cryptsetup-keys.d/</filename> directories, if present. Otherwise, the password has to be
manually entered during system boot. For swap encryption, <filename>/dev/urandom</filename> may be used
as key file.</para>
<para>The third field specifies an absolute path to a file to read the encryption key from. Optionally,
the path may be followed by <literal>:</literal> and an fstab device specification (e.g. starting with
<literal>LABEL=</literal> or similar); in which case, the path is relative to the device file system
root. If the field is not present or set to <literal>none</literal> or <literal>-</literal>, a key file
named after the volume to unlock (i.e. the first column of the line), suffixed with
<filename>.key</filename> is automatically loaded from the <filename>/etc/cryptsetup-keys.d/</filename>
and <filename>/run/cryptsetup-keys.d/</filename> directories, if present. Otherwise, the password has to
be manually entered during system boot. For swap encryption, <filename>/dev/urandom</filename> may be
used as key file.</para>
<para>The fourth field, if present, is a comma-delimited list of
options. The following options are recognized:</para>