pulseaudio - The PulseAudio Sound System


   pulseaudio [options]

   pulseaudio --help

   pulseaudio --version

   pulseaudio --dump-conf

   pulseaudio --dump-modules

   pulseaudio --dump-resample-methods

   pulseaudio --cleanup-shm

   pulseaudio --start

   pulseaudio --kill

   pulseaudio --check


   PulseAudio is a networked low-latency sound server for Linux, POSIX and
   Windows systems.


   -h | --help
          Show help.

          Show version information.

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

          List  available  loadable  modules.  Combine  with -v for a more
          elaborate listing.

          List available audio resamplers.

          Identify  stale  PulseAudio  POSIX  shared  memory  segments  in
          /dev/shm  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
          /dev/shm (e.g. Linux).

          Start PulseAudio if it is not running  yet.  This  is  different
          from  starting PulseAudio without --start which would fail if PA
          is  already  running.  PulseAudio  is  guaranteed  to  be  fully
          initialized when this call returns. Implies --daemonize.

   -k | --kill
          Kill  an  already  running PulseAudio daemon of the calling user
          (Equivalent to sending a SIGTERM).

          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.

          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 --disallow-module-loading (see

   -D | --daemonize[=BOOL]
          Daemonize after startup, i.e. detach  from  the  terminal.  Note
          that   when   running  as  a  systemd  service  you  should  use
          --daemonize=no for systemd notification to work.

          Fail startup when any of the commands specified in  the  startup
          script default.pa (see below) fails.

          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
          --system  above).  It is recommended to enable this, since it is
          only a negligible security risk (see below).

          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 --system above). It is
          recommended to enable this only for trusted users, since it is a
          major security risk (see below).

          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
          --system  is  used  (see  above). Note however, that this breaks
          certain features like automatic module loading on hot plug.

          Disallow user requested exit

          Terminate the daemon when  idle  and  the  specified  number  of
          seconds passed.

          Unload  autoloaded  samples from the cache when the haven't been
          used for the specified number of seconds.

          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
          error,  warn,  notice, info, debug. Default log level is notice,
          i.e. all log messages with lower log levels are printed:  error,
          warn, notice.

   -v | --verbose
          Increase  the configured verbosity level by one (see --log-level
          above). Specify multiple times to increase  log  level  multiple

          Specify  the  log target. If set to auto (which is the default),
          then logging is directed to syslog when --daemonize  is  passed,
          otherwise  to  STDERR.  If set to journal logging is directed to
          the systemd journal. If set to file:PATH, logging is directed to
          the  file  indicated by PATH. newfile:PATH is otherwise the same
          as file:PATH, but existing files are never overwritten.  If  the
          specified  file  already  exists,  a suffix is added to the file
          name to avoid overwriting.

          Show source code location in log messages.

          Show timestamps in log messages.

          When FRAMES is greater than 0, log  for  each  message  a  stack
          trace up to the number of specified stack frames.

   -p | --dl-search-path=PATH
          Set the search path for dynamic shared objects (plugins).

          Use  the  specified  resampler  by default (See --dump-resample-
          methods above for possible values).

          Create a PID file. If this options is disabled it is possible to
          run multiple sound servers per user.

          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  mechanism  is  useful  when  debugging
          PulseAudio  with  tools  like  valgrind(1)   which   slow   down

          PulseAudio  clients  and  the server can exchange audio data via
          POSIX or memfd 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
          --system enabled (see above).

          PulseAudio clients and the server can exchange  audio  data  via
          memfds  - the anonymous Linux Kernel shared memory mechanism (on
          kernels  that  support  this).  If  disabled   PulseAudio   will
          communicate via POSIX shared memory.

   -L | --load="MODULE ARGUMENTS"
          Load the specified plugin module with the specified arguments.

   -F | --file=FILENAME
          Run  the  specified script on startup. May be specified multiple
          times to specify multiple scripts to be run  in  order.  Combine
          with -n to disable loading of the default script default.pa (see

   -C     Open a command interpreter on STDIN/STDOUT after  startup.  This
          may  be used to configure PulseAudio dynamically during runtime.
          Equivalent to --load=module-cli.

   -n     Don't  load  default  script  file  default.pa  (see  below)  on
          startup. Useful in conjunction with -C or --file.


   ~/.config/pulse/daemon.conf,    /etc/pulse/daemon.conf:   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
   pulse-daemon.conf(5) for more information.

   ~/.config/pulse/default.pa,    /etc/pulse/default.pa:    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 default.pa(5) for more information.

   ~/.config/pulse/client.conf,    /etc/pulse/client.conf:   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 pulse-client.conf(5) for more information.


   SIGINT, SIGTERM: the PulseAudio daemon will shut down (Same as --kill).

   SIGHUP: dump a long status report to STDOUT or syslog, depending on the

   SIGUSR1:   load   module-cli,   allowing  runtime  reconfiguration  via

   SIGUSR2:    load     module-cli-protocol-unix,     allowing     runtime
   reconfiguration   via   a   AF_UNIX   socket.  See  pacmd(1)  for  more


   Group pulse-rt: 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).

   Group  pulse-access:  if  PulseAudio is running as a system daemon (see
   --system 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.

   User pulse, group pulse: if PulseAudio is running as  a  system  daemon
   (see  --system  above)  and  is  started  as  root the daemon will drop
   privileges 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


   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 privileges 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.

   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 --realtime (see above) or enabled the
   appropriate option in daemon.conf. Since acquiring realtime  scheduling
   is  a privileged 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:

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

   Alternatively, the SUID root bit can be set for the PulseAudio  binary.
   Then,  the  daemon  will  drop  root privileges 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 pulse-rt group (see
   above). For all other users all capabilities are  dropped  immediately.
   The  advantage  of  this  solution is that the real-time privileges are
   only granted to  the  PulseAudio  daemon  --  not  to  all  the  user's

   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 --high-priority (see above) when starting  PulseAudio  and  may
   also  be  enabled  with the appropriate option in daemon.conf. Negative
   nice levels can only be enabled when  the  appropriate  resource  limit
   RLIMIT_NICE  is  set  (see setrlimit(2) for more information), possibly
   configured  in  /etc/security/limits.conf.  A  resource  limit  of   31
   (corresponding with nice level -11) is recommended.


   The  PulseAudio  client  libraries  check  for  the  existence  of  the
   following environment variables and change  their  local  configuration

   $PULSE_SERVER:  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.  The  server  string is a list of server
   addresses separated by whitespace which are tried  in  turn.  A  server
   address  consists  of  an optional address type specifier (unix:, tcp:,
   tcp4:, tcp6:), followed by a path or host address. A host  address  may
   include  an optional port number. A server address may be prefixed by a
   string enclosed in {}. In this case the  following  server  address  is
   ignored  unless  the  prefix  string  equals  the local hostname or the
   machine id (/etc/machine-id).

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

   $PULSE_SOURCE: 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.

   $PULSE_BINARY: path of PulseAudio executable to run when  server  auto-
   spawning is used.

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

   $PULSE_COOKIE: path of file that contains the PulseAudio authentication
   cookie. Defaults to ~/.config/pulse/cookie.

   These  environment  settings  take  precedence  --  if  set -- over the
   configuration settings from client.conf (see above).


   The  PulseAudio  Developers  <pulseaudio-discuss   (at)   lists   (dot)
   freedesktop     (dot)    org>;    PulseAudio    is    available    from


   pulse-daemon.conf(5), default.pa(5), pulse-client.conf(5), pacmd(1)


Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.

Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.

Free Software

Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.

Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.

Free Books

The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.

Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.


Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.

Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.