[pulseaudio] / man / pulseaudio.1.xml.in

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<manpage name="pulseaudio" section="1" desc="The PulseAudio Sound System">

  <synopsis>
    <cmd>pulseaudio [<arg>options</arg>]</cmd>
    <cmd>pulseaudio <opt>--help</opt></cmd>
    <cmd>pulseaudio <opt>--version</opt></cmd>
    <cmd>pulseaudio <opt>--dump-conf</opt></cmd>
    <cmd>pulseaudio <opt>--dump-modules</opt></cmd>
    <cmd>pulseaudio <opt>--dump-resample-methods</opt></cmd>
    <cmd>pulseaudio <opt>--cleanup-shm</opt></cmd>
    <cmd>pulseaudio <opt>--start</opt></cmd>
    <cmd>pulseaudio <opt>--kill</opt></cmd>
    <cmd>pulseaudio <opt>--check</opt></cmd>
  </synopsis>

  <description>
    <p>PulseAudio is a networked low-latency sound server for Linux, POSIX and Windows systems.</p>
  </description>

  <options>

    <option>
      <p><opt>-h | --help</opt></p>

      <optdesc><p>Show help.</p></optdesc>
    </option>

    <option>
      <p><opt>--version</opt></p>

      <optdesc><p>Show version information.</p></optdesc>
    </option>

    <option>
      <p><opt>--dump-conf</opt></p>

      <optdesc><p>Load the daemon configuration file
      <file>daemon.conf</file> (see below), parse remaining
      configuration options on the command line and dump the resulting
      daemon configuration, in a format that is compatible with
      <file>daemon.conf</file>.</p></optdesc>
    </option>

    <option>
      <p><opt>--dump-modules</opt></p>

      <optdesc><p>List available loadable modules. Combine with
      <opt>-v</opt> for a more elaborate listing.</p></optdesc>
    </option>

    <option>
      <p><opt>--dump-resample-methods</opt></p>
      <optdesc><p>List available audio resamplers.</p></optdesc>
    </option>

    <option>
      <p><opt>--cleanup-shm</opt></p>

      <optdesc><p>Identify stale PulseAudio POSIX shared memory
      segments in <file>/dev/shm</file> and remove them if
      possible. This is done implicitly whenever a new daemon starts
      up or a client tries to connect to a daemon. It should normally
      not be necessary to issue this command by hand. Only available
      on systems with POSIX shared memory segments implemented via a
      virtual file system mounted to <file>/dev/shm</file>
      (e.g. Linux).</p></optdesc>
    </option>

    <option>
      <p><opt>--start</opt></p>

      <optdesc><p>Start PulseAudio if it is not running yet. This is
      different from starting PulseAudio without <opt>--start</opt>
      which would fail if PA is already running. PulseAudio is
      guaranteed to be fully initialized when this call
      returns. Implies <opt>--daemon</opt>.</p></optdesc>
    </option>

    <option>
      <p><opt>-k | --kill</opt></p>

      <optdesc><p>Kill an already running PulseAudio daemon of the
      calling user (Equivalent to sending a SIGTERM).</p></optdesc>
    </option>

    <option>
      <p><opt>--check</opt></p>

      <optdesc><p>Return 0 as return code when the PulseAudio daemon
      is already running for the calling user, or non-zero
      otherwise. Produces no output on the console except for errors
      to stderr.</p></optdesc>
    </option>


    <option>
      <p><opt>--system</opt><arg>[=BOOL]</arg></p>

      <optdesc><p>Run as system-wide instance instead of
      per-user. Please note that this disables certain features of
      PulseAudio and is generally not recommended unless the system
      knows no local users (e.g. is a thin client). This feature needs
      special configuration and a dedicated UNIX user set up. It is
      highly recommended to combine this with
      <opt>--disallow-module-loading</opt> (see below).</p></optdesc>
    </option>

    <option>
      <p><opt>-D | --daemonize</opt><arg>[=BOOL]</arg></p>

      <optdesc><p>Daemonize after startup, i.e. detach from the
      terminal.</p></optdesc>
    </option>

    <option>
      <p><opt>--fail</opt><arg>[=BOOL]</arg></p>

      <optdesc><p>Fail startup when any of the commands specified in
      the startup script <file>default.pa</file> (see below)
      fails.</p></optdesc>
    </option>

    <option>
      <p><opt>--high-priority</opt><arg>[=BOOL]</arg></p>

      <optdesc><p>Try to acquire a high Unix nice level. This will
      only succeed if the calling user has a non-zero RLIMIT_NICE
      resource limit set (on systems that support this), or we're
      called SUID root (see below), or we are configure to be run as
      system daemon (see <arg>--system</arg> above). It is recommended
      to enable this, since it is only a negligible security risk (see
      below).</p></optdesc>
    </option>

    <option>
      <p><opt>--realtime</opt><arg>[=BOOL]</arg></p>

      <optdesc><p>Try to acquire a real-time scheduling for
      PulseAudio's I/O threads. This will only succeed if the calling
      user has a non-zero RLIMIT_RTPRIO resource limit set (on systems
      that support this), or we're called SUID root (see below), or we
      are configure to be run as system daemon (see
      <arg>--system</arg> above). It is recommended to enable this
      only for trusted users, since it is a major security risk (see
      below).</p></optdesc>
    </option>

    <option>
      <p><opt>--disallow-module-loading</opt><arg>[=BOOL]</arg></p>

      <optdesc><p>Disallow module loading after startup. This is a
      security feature since it disallows additional module loading
      during runtime and on user request. It is highly recommended
      when <arg>--system</arg> is used (see above). Note however, that
      this breaks certain features like automatic module loading on hot
      plug.</p></optdesc>

    </option>

    <option>
      <p><opt>--exit-idle-time</opt><arg>=SECS</arg></p>

      <optdesc><p>Terminate the daemon when idle and the specified
      number of seconds passed.</p></optdesc>
    </option>

    <option>
      <p><opt>--scache-idle-time</opt><arg>=SECS</arg></p>

      <optdesc><p>Unload autoloaded samples from the cache when the
      haven't been used for the specified number of
      seconds.</p></optdesc>
    </option>

    <option>
      <p><opt>--log-level</opt><arg>[=LEVEL]</arg></p>

      <optdesc><p>If an argument is passed, set the log level to the
      specified value, otherwise increase the configured verbosity
      level by one. The log levels are numerical from 0 to 4,
      corresponding to <arg>error</arg>, <arg>warn</arg>,
      <arg>notice</arg>, <arg>info</arg>, <arg>debug</arg>. Default
      log level is <arg>notice</arg>, i.e. all log messages with lower
      log levels are printed: <arg>error</arg>, <arg>warn</arg>,
      <arg>notice</arg>.</p></optdesc>
    </option>

    <option>
      <p><opt>-v</opt></p>

      <optdesc><p>Increase the configured verbosity level by one (see
      <opt>--log-level</opt> above). Specify multiple times to
      increase log level multiple times.</p></optdesc>
    </option>

    <option>
      <p><opt>--log-target</opt><arg>={auto,syslog,stderr,file:PATH}</arg></p>

      <optdesc><p>Specify the log target. If set to <arg>auto</arg>
      (which is the default), then logging is directed to syslog when
      <opt>--daemonize</opt> is passed, otherwise to
      STDERR. If set to <arg>file:PATH</arg>, logging is directed to
      the file indicated by PATH.</p></optdesc>
    </option>

    <option>
      <p><opt>--p | --dl-search-path</opt><arg>=PATH</arg></p>

      <optdesc><p>Set the search path for dynamic shared objects
      (plugins).</p></optdesc>
    </option>

    <option>
      <p><opt>--resample-method</opt><arg>=METHOD</arg></p>

      <optdesc><p>Use the specified resampler by default (See
      <opt>--dump-resample-methods</opt> above for possible
      values).</p></optdesc>
    </option>

    <option>
      <p><opt>--use-pid-file</opt><arg>[=BOOL]</arg></p>

      <optdesc><p>Create a PID file. If this options is disabled it is possible to run multiple sound servers per user.</p></optdesc>
    </option>

    <option>
      <p><opt>--no-cpu-limit</opt><arg>[=BOOL]</arg></p>

      <optdesc><p>Do not install CPU load limiter on platforms that
      support it. By default, PulseAudio will terminate itself when it
      notices that it takes up too much CPU time. This is useful as a
      protection against system lockups when real-time scheduling is
      used (see below). Disabling this meachnism is useful when
      debugging PulseAudio with tools like <manref name="valgrind"
      section="1"/> which slow down execution.</p></optdesc>
    </option>

    <option>
      <p><opt>--disable-shm</opt><arg>[=BOOL]</arg></p>

      <optdesc><p>PulseAudio clients and the server can exchange audio
      data via POSIX shared memory segments (on systems that support
      this). If disabled PulseAudio will communicate exclusively over
      sockets. Please note that data transfer via shared memory
      segments is always disabled when PulseAudio is running with
      <opt>--system</opt> enabled (see above).</p></optdesc>
    </option>

    <option>
      <p><opt>-L | --load</opt><arg>="MODULE ARGUMENTS"</arg></p>

      <optdesc><p>Load the specified plugin module with the specified
      arguments.</p></optdesc>
    </option>

    <option>
      <p><opt>-F | --file</opt><arg>=FILENAME</arg></p>

      <optdesc><p>Run the specified script on startup. May be
      specified multiple times to specify multiple scripts to be run
      in order. Combine with <opt>-n</opt> to disable loading of the
      default script <file>default.pa</file> (see below).</p></optdesc>
    </option>
    <option>
      <p><opt>-C</opt></p>

      <optdesc><p>Open a command interpreter on STDIN/STDOUT after
      startup. This may be used to configure PulseAudio dynamically
      during runtime. Equivalent to
      <opt>--load</opt><arg>=module-cli</arg>.</p></optdesc>
    </option>
    <option>
      <p><opt>-n</opt></p>

      <optdesc><p>Don't load default script file
      <file>default.pa</file> (see below) on startup. Useful in
      conjunction with <opt>-C</opt> or
      <opt>--file</opt>.</p></optdesc>
    </option>


  </options>

  <section name="Files">

    <p><file>~/.pulse/daemon.conf</file>,
    <file>@PA_DEFAULT_CONFIG_DIR@/daemon.conf</file>: configuration settings
    for the PulseAudio daemon. If the version in the user's home
    directory does not exist the global configuration file is
    loaded. See <manref name="pulse-daemon.conf" section="5"/> for
    more information.</p>

    <p><file>~/.pulse/default.pa</file>,
    <file>@PA_DEFAULT_CONFIG_DIR@/default.pa</file>: the default configuration
    script to execute when the PulseAudio daemon is started. If the
    version in the user's home directory does not exist the global
    configuration script is loaded. See <manref name="default.pa"
    section="5"/> for more information.</p>

    <p><file>~/.pulse/client.conf</file>,
    <file>@PA_DEFAULT_CONFIG_DIR@/client.conf</file>: configuration settings
    for PulseAudio client applications. If the version in the user's
    home directory does not exist the global configuration file is
    loaded.  See <manref name="pulse-client.conf" section="5"/> for
    more information.</p>

  </section>

  <section name="Signals">

    <p><arg>SIGINT, SIGTERM</arg>: the PulseAudio daemon will shut
    down (Same as <opt>--kill</opt>).</p>

    <p><arg>SIGHUP</arg>: dump a long status report to STDOUT or
    syslog, depending on the configuration.</p>

    <p><arg>SIGUSR1</arg>: load module-cli, allowing runtime
    reconfiguration via STDIN/STDOUT.</p>

    <p><arg>SIGUSR2</arg>: load module-cli-protocol-unix, allowing
    runtime reconfiguration via a AF_UNIX socket. See <manref
    name="pacmd" section="1"/> for more information.</p>

  </section>

  <section name="UNIX Groups and users">

    <p>Group <arg>pulse-rt</arg>: if the PulseAudio binary is marked
    SUID root, then membership of the calling user in this group
    decides whether real-time and/or high-priority scheduling is
    enabled. Please note that enabling real-time scheduling is a
    security risk (see below).</p>

    <p>Group <arg>pulse-access</arg>: if PulseAudio is running as a system
    daemon (see <opt>--system</opt> above) access is granted to
    members of this group when they connect via AF_UNIX sockets. If
    PulseAudio is running as a user daemon this group has no
    meaning.</p>

    <p>User <arg>pulse</arg>, group <arg>pulse</arg>: if PulseAudio is running as a system
    daemon (see <opt>--system</opt> above) and is started as root the
    daemon will drop priviliges and become a normal user process using
    this user and group. If PulseAudio is running as a user daemon
    this user and group has no meaning.</p>
  </section>

  <section name="Real-time and high-priority scheduling">
    <p>To minimize the risk of drop-outs during playback it is
    recommended to run PulseAudio with real-time scheduling if the
    underlying platform supports it. This decouples the scheduling
    latency of the PulseAudio daemon from the system load and is thus
    the best way to make sure that PulseAudio always gets CPU time
    when it needs it to refill the hardware playback
    buffers. Unfortunately this is a security risk on most systems,
    since PulseAudio runs as user process, and giving realtime
    scheduling priviliges to a user process always comes with the risk
    that the user misuses it to lock up the system -- which is
    possible since making a process real-time effectively disables
    preemption.</p>

    <p>To minimize the risk PulseAudio by default does not enable
    real-time scheduling. It is however recommended to enable it
    on trusted systems. To do that start PulseAudio with
    <opt>--realtime</opt> (see above) or enabled the appropriate option in
    <file>daemon.conf</file>. Since acquiring realtime scheduling is a
    priviliged operation on most systems, some special changes to the
    system configuration need to be made to allow them to the calling
    user. Two options are available:</p>

    <p>On newer Linux systems the system resource limit RLIMIT_RTPRIO
    (see <manref name="setrlimit" section="2"/> for more information)
    can be used to allow specific users to acquire real-time
    scheduling. This can be configured in
    <file>/etc/security/limits.conf</file>, a resource limit of 9 is recommended.</p>

    <p>Alternatively, the SUID root bit can be set for the PulseAudio
    binary. Then, the daemon will drop root priviliges immediately on
    startup, however retain the CAP_NICE capability (on systems that
    support it), but only if the calling user is a member of the
    <arg>pulse-rt</arg> group (see above). For all other users all
    capababilities are dropped immediately. The advantage of this
    solution is that the real-time priviliges are only granted to the
    PulseAudio daemon -- not to all the user's processes.</p>

    <p>Alternatively, if the risk of locking up the machine is
    considered too big to enable real-time scheduling, high-priority
    scheduling can be enabled instead (i.e. negative nice level). This
    can be enabled by passing <opt>--high-priority</opt> (see above)
    when starting PulseAudio and may also be enabled with the
    approriate option in <file>daemon.conf</file>. Negative nice
    levels can only be enabled when the appropriate resource limit
    RLIMIT_NICE is set (see <manref name="setrlimit" section="2"/> for
    more information), possibly configured in
    <file>/etc/security/limits.conf</file>. A resource limit of 31
    (corresponding with nice level -11) is recommended.</p>
  </section>

  <section name="Environment variables">

    <p>The PulseAudio client libraries check for the existance of the
    following environment variables and change their local configuration accordingly:</p>

    <p><arg>$PULSE_SERVER</arg>: the server string specifying the server to connect to when a client asks for a sound server connection and doesn't explicitly ask for a specific server.</p>

    <p><arg>$PULSE_SINK</arg>: the symbolic name of the sink to connect to when a client creates a playback stream and doesn't explicitly ask for a specific sink.</p>

    <p><arg>$PULSE_SOURCE</arg>: the symbolic name of the source to connect to when a client creates a record stream and doesn't explicitly ask for a specific source.</p>

    <p><arg>$PULSE_BINARY</arg>: path of PulseAudio executable to run when server auto-spawning is used.</p>

    <p><arg>$PULSE_CLIENTCONFIG</arg>: path of file that shall be read instead of <file>client.conf</file> (see above) for client configuration.</p>

    <p>These environment settings take precedence -- if set -- over the configuration settings from <file>client.conf</file> (see above).</p>

  </section>

  <section name="Authors">
    <p>The PulseAudio Developers &lt;@PACKAGE_BUGREPORT@&gt;; PulseAudio is available from <url href="@PACKAGE_URL@"/></p>
  </section>

  <section name="See also">
    <p>
      <manref name="pulse-daemon.conf" section="5"/>, <manref name="default.pa" section="5"/>, <manref name="pulse-client.conf" section="5"/>, <manref name="pacmd" section="1"/>
    </p>
  </section>

</manpage>