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 RLIMITNICE 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 RLIMITRTPRIO 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 AFUNIX 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 AFUNIX 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 RLIMITRTPRIO (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 CAPNICE 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 RLIMITNICE 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:
$PULSESERVER: 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).
$PULSESINK: 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.
$PULSESOURCE: 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.
$PULSEBINARY: path of PulseAudio executable to run when server auto- spawning is used.
$PULSECLIENTCONFIG: path of file that shall be read instead of client.conf (see above) for client configuration.
$PULSECOOKIE: 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
freedesktop (dot) org>; PulseAudio is available from http://pulseau‐ dio.org/ SEE ALSO pulse-daemon.conf(5), default.pa(5), pulse-client.conf(5), pacmd(1) Manuals User pulseaudio(1)