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Updated: Thursday, June 13, 2019
 
 

pulseaudio (1)

Name

pulseaudio - The PulseAudio Sound System

Synopsis

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

Description

pulseaudio(1)               General Commands Manual              pulseaudio(1)



NAME
       pulseaudio - The PulseAudio Sound System

SYNOPSIS
       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

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

OPTIONS
       -h | --help
              Show help.

       --version
              Show version information.

       --dump-conf
              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.

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

       --dump-resample-methods
              List available audio resamplers.

       --cleanup-shm
              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 com-
              mand 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
              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  ini-
              tialized when this call returns. Implies --daemonize.

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

       --check
              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.

       --system[=BOOL]
              Run as system-wide instance instead  of  per-user.  Please  note
              that  this disables certain features of PulseAudio and is gener-
              ally not recommended unless the  system  knows  no  local  users
              (e.g.  is  a thin client). This feature needs special configura-
              tion and a dedicated UNIX user set up. It is highly  recommended
              to combine this with --disallow-module-loading (see below).

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

       --fail[=BOOL]
              Fail  startup  when any of the commands specified in the startup
              script default.pa (see below) fails.

       --high-priority[=BOOL]
              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).

       --realtime[=BOOL]
              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  config-
              ure  to be run as system daemon (see --system above). It is rec-
              ommended to enable this only for trusted users, since  it  is  a
              major security risk (see below).

       --disallow-module-loading[=BOOL]
              Disallow  module  loading after startup. This is a security fea-
              ture 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  fea-
              tures like automatic module loading on hot plug.

       --disallow-exit[=BOOL]
              Disallow user requested exit

       --exit-idle-time=SECS
              Terminate  the daemon when idle and the specified number of sec-
              onds passed.

       --scache-idle-time=SECS
              Unload autoloaded samples from the cache when the  haven't  been
              used for the specified number of seconds.

       --log-level[=LEVEL]
              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
              times.

       --log-target={auto,syslog,journal,stderr,file:PATH,newfile:PATH}
              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.

       --log-meta[=BOOL]
              Show source code location in log messages.

       --log-time[=BOOL]
              Show timestamps in log messages.

       --log-backtrace=FRAMES
              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).

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

       --use-pid-file[=BOOL]
              Create a PID file. If this options is disabled it is possible to
              run multiple sound servers per user.

       --no-cpu-limit[=BOOL]
              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 execu-
              tion.

       --disable-shm[=BOOL]
              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 seg-
              ments is always disabled when PulseAudio is running with  --sys-
              tem enabled (see above).

       --enable-memfd[=BOOL]
              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 communi-
              cate 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
              below).

       -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.

FILES
       ~/.config/pulse/daemon.conf, /etc/pulse/daemon.conf: configuration set-
       tings  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 configu-
       ration script to execute when the PulseAudio daemon is started. If  the
       version in the user's home directory does not exist the global configu-
       ration script is loaded. See default.pa(5) for more information.

       ~/.config/pulse/client.conf, /etc/pulse/client.conf: configuration set-
       tings  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.

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

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

       SIGUSR1:  load  module-cli,  allowing   runtime   reconfiguration   via
       STDIN/STDOUT.

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

UNIX GROUPS AND USERS
       Group pulse-rt: if the PulseAudio binary is marked SUID root, then mem-
       bership  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 privi-
       leges 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 mean-
       ing.

REAL-TIME AND HIGH-PRIORITY SCHEDULING
       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 sys-
       tems, since PulseAudio runs as user process, and giving realtime sched-
       uling  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/secu-
       rity/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, how-
       ever 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 processes.

       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 (corre-
       sponding with nice level -11) is recommended.

ENVIRONMENT VARIABLES
       The PulseAudio client libraries check for the existence of the  follow-
       ing  environment variables and change their local configuration accord-
       ingly:

       $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
       sink.

       $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  spe-
       cific 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  con-
       figuration settings from client.conf (see above).

AUTHORS
       The   PulseAudio   Developers   <pulseaudio-discuss  (at)  lists  (dot)
       freedesktop (dot) org>; PulseAudio is  available  from  http://pulseau-
       dio.org/


ATTRIBUTES
       See attributes(7) for descriptions of the following attributes:


       +---------------+--------------------------+
       |ATTRIBUTE TYPE |     ATTRIBUTE VALUE      |
       +---------------+--------------------------+
       |Availability   | library/audio/pulseaudio |
       +---------------+--------------------------+
       |Stability      | Pass-through volatile    |
       +---------------+--------------------------+
SEE ALSO
       pulse-daemon.conf(5), default.pa(5), pulse-client.conf(5), pacmd(1)



NOTES
       This     software     was    built    from    source    available    at
       https://github.com/oracle/solaris-userland.   The  original   community
       source  was  downloaded  from  http://freedesktop.org/software/pulseau-
       dio/releases/pulseaudio-9.0.tar.xz

       Further information about this software can be found on the open source
       community website at http://freedesktop.org/software/pulseaudio.



Manuals                              User                        pulseaudio(1)