pulseaudio

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
              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
              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).

       --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
              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
              below).

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

       --exit-idle-time=SECS
              Terminate the daemon after the last client quit and this time in
              seconds passed. Use a negative value to disable this feature.
              Defaults to 20.

              When PulseAudio runs in the per-user mode and detects a login
              session, then any positive value will be reset to 0 so that
              PulseAudio will terminate immediately on logout. A positive
              value therefore has effect only in environments where there's no
              support for login session tracking. A negative value can still
              be used to disable any automatic exit.

              When PulseAudio runs in the system mode, automatic exit is
              always disabled, so this option does nothing.

       --scache-idle-time=SECS
              Unload autoloaded samples from the cache when they 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
              execution.

       --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
              segments is always disabled when PulseAudio is running with
              --system 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
              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
              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
       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.

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
       reconfiguration 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
       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
       meaning.

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
       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
       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
       (corresponding with nice level -11) is recommended.

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

       $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
       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).

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

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



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