man/systemd-ask-password.xml

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   8   Copyright 2011 Lennart Poettering
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  23
  24 <refentry id="systemd-ask-password"
  25     xmlns:xi="http://www.w3.org/2001/XInclude">
  26
  27   <refentryinfo>
  28     <title>systemd-ask-password</title>
  29     <productname>systemd</productname>
  30
  31     <authorgroup>
  32       <author>
  33         <contrib>Developer</contrib>
  34         <firstname>Lennart</firstname>
  35         <surname>Poettering</surname>
  36         <email>lennart@poettering.net</email>
  37       </author>
  38     </authorgroup>
  39   </refentryinfo>
  40
  41   <refmeta>
  42     <refentrytitle>systemd-ask-password</refentrytitle>
  43     <manvolnum>1</manvolnum>
  44   </refmeta>
  45
  46   <refnamediv>
  47     <refname>systemd-ask-password</refname>
  48     <refpurpose>Query the user for a system password</refpurpose>
  49   </refnamediv>
  50
  51   <refsynopsisdiv>
  52     <cmdsynopsis>
  53       <command>systemd-ask-password <arg choice="opt" rep="repeat">OPTIONS</arg> <arg choice="opt">MESSAGE</arg></command>
  54     </cmdsynopsis>
  55   </refsynopsisdiv>
  56
  57   <refsect1>
  58     <title>Description</title>
  59
  60     <para><command>systemd-ask-password</command> may be used to query
  61     a system password or passphrase from the user, using a question
  62     message specified on the command line. When run from a TTY it will
  63     query a password on the TTY and print it to standard output. When
  64     run with no TTY or with <option>--no-tty</option> it will query
  65     the password system-wide and allow active users to respond via
  66     several agents. The latter is only available to privileged
  67     processes.</para>
  68
  69     <para>The purpose of this tool is to query system-wide passwords
  70     -- that is passwords not attached to a specific user account.
  71     Examples include: unlocking encrypted hard disks when they are
  72     plugged in or at boot, entering an SSL certificate passphrase for
  73     web and VPN servers.</para>
  74
  75     <para>Existing agents are:
  76     <itemizedlist>
  77
  78       <listitem><para>A boot-time password agent asking the user for
  79       passwords using Plymouth</para></listitem>
  80
  81       <listitem><para>A boot-time password agent querying the user
  82       directly on the console</para></listitem>
  83
  84       <listitem><para>An agent requesting password input via a
  85       <citerefentry
  86       project='man-pages'><refentrytitle>wall</refentrytitle><manvolnum>1</manvolnum></citerefentry>
  87       message</para></listitem>
  88
  89       <listitem><para>A command line agent which can be started
  90       temporarily to process queued password
  91       requests</para></listitem>
  92
  93       <listitem><para>A TTY agent that is temporarily spawned during
  94       <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
  95       invocations</para></listitem>
  96     </itemizedlist></para>
  97
  98     <para>Additional password agents may be implemented according to
  99     the <ulink
 100     url="http://www.freedesktop.org/wiki/Software/systemd/PasswordAgents">systemd
 101     Password Agent Specification</ulink>.</para>
 102
 103     <para>If a password is queried on a TTY, the user may press TAB to
 104     hide the asterisks normally shown for each character typed.
 105     Pressing Backspace as first key achieves the same effect.</para>
 106
 107   </refsect1>
 108
 109   <refsect1>
 110     <title>Options</title>
 111
 112     <para>The following options are understood:</para>
 113
 114     <variablelist>
 115       <varlistentry>
 116         <term><option>--icon=</option></term>
 117
 118         <listitem><para>Specify an icon name alongside the password
 119         query, which may be used in all agents supporting graphical
 120         display. The icon name should follow the <ulink
 121         url="http://standards.freedesktop.org/icon-naming-spec/icon-naming-spec-latest.html">XDG
 122         Icon Naming Specification</ulink>.</para></listitem>
 123       </varlistentry>
 124
 125       <varlistentry>
 126         <term><option>--id=</option></term>
 127         <listitem><para>Specify an identifier for this password
 128         query. This identifier is freely choosable and allows
 129         recognition of queries by involved agents. It should include
 130         the subsystem doing the query and the specific object the
 131         query is done for. Example:
 132         <literal>--id=cryptsetup:/dev/sda5</literal>.</para></listitem>
 133       </varlistentry>
 134
 135       <varlistentry>
 136         <term><option>--keyname=</option></term>
 137         <listitem><para>Configure a kernel keyring key name to use as
 138         cache for the password. If set, then the tool will try to push
 139         any collected passwords into the kernel keyring of the root
 140         user, as a key of the specified name. If combined with
 141         <option>--accept-cached</option>, it will also try to retrieve
 142         such cached passwords from the key in the kernel keyring
 143         instead of querying the user right away. By using this option,
 144         the kernel keyring may be used as effective cache to avoid
 145         repeatedly asking users for passwords, if there are multiple
 146         objects that may be unlocked with the same password. The
 147         cached key will have a timeout of 2.5min set, after which it
 148         will be purged from the kernel keyring. Note that it is
 149         possible to cache multiple passwords under the same keyname,
 150         in which case they will be stored as NUL-separated list of
 151         passwords. Use
 152         <citerefentry project='die-net'><refentrytitle>keyctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 153         to access the cached key via the kernel keyring
 154         directly. Example: <literal>--keyname=cryptsetup</literal></para></listitem>
 155       </varlistentry>
 156
 157       <varlistentry>
 158         <term><option>--timeout=</option></term>
 159
 160         <listitem><para>Specify the query timeout in seconds. Defaults
 161         to 90s. A timeout of 0 waits indefinitely. </para></listitem>
 162       </varlistentry>
 163
 164       <varlistentry>
 165         <term><option>--echo</option></term>
 166
 167         <listitem><para>Echo the user input instead of masking it.
 168         This is useful when using
 169         <filename>systemd-ask-password</filename> to query for
 170         usernames. </para></listitem>
 171       </varlistentry>
 172
 173       <varlistentry>
 174         <term><option>--no-tty</option></term>
 175
 176         <listitem><para>Never ask for password on current TTY even if
 177         one is available. Always use agent system.</para></listitem>
 178       </varlistentry>
 179
 180       <varlistentry>
 181         <term><option>--accept-cached</option></term>
 182
 183         <listitem><para>If passed, accept cached passwords, i.e.
 184         passwords previously entered.</para></listitem>
 185       </varlistentry>
 186
 187       <varlistentry>
 188         <term><option>--multiple</option></term>
 189
 190         <listitem><para>When used in conjunction with
 191         <option>--accept-cached</option> accept multiple passwords.
 192         This will output one password per line.</para></listitem>
 193       </varlistentry>
 194
 195       <xi:include href="standard-options.xml" xpointer="help" />
 196     </variablelist>
 197
 198   </refsect1>
 199
 200   <refsect1>
 201     <title>Exit status</title>
 202
 203     <para>On success, 0 is returned, a non-zero failure code
 204     otherwise.</para>
 205   </refsect1>
 206
 207   <refsect1>
 208     <title>See Also</title>
 209     <para>
 210       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 211       <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 212       <citerefentry project='die-net'><refentrytitle>keyctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 213       <citerefentry project='die-net'><refentrytitle>plymouth</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 214       <citerefentry project='man-pages'><refentrytitle>wall</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 215     </para>
 216   </refsect1>
 217
 218 </refentry>