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nasd - Network Audio System server
nasd [:listen port offset]
[-option ...]
nasd is the generic name for the Network Audio System
server. It is frequently a link or a copy of the appropriate server binary
for driving the most frequently used server on a given machine.
The server is usually started from /etc/rc or a user's startup
script.
When the Network Audio System server starts up, it takes over /dev/audio.
Note, that if ReleaseDevice is set to TRUE [default] in the nasd.conf file,
nasd will relinquish control of the audio device whenever it has finished
playing a sound. This means you can use other non-NAS applications when
nasd is running, as long as nasd isn't currently playing a song. If ReleaseDevice
is set to FALSE in the nasd.conf file, applications that attempt to access
/dev/audio themselves will fail while nasd is running.
The
Network Audio System server supports connections made using the following
reliable byte-streams:
- TCP/IP
The server listens on port 8000+n, where n is the listen port offset. - Unix
Domain
- The X server uses /tmp/.sockets/audion as the filename for the socket,
where n is the display number.
All of the Network Audio System servers
accept the following generic command line options. Options specific to
a particular server may also be available, and are not listed here. Try
'nasd -?' for a list of those options, if available.
- -aa
- Allows any client to
connect. By default, access is allowed only to authenticated clients.
- -local
- Allows only clients on the local host to connect. By default, access is
allowed to local and remote hosts.
- -v
- Enable verbose messages. This option
overrides the nasd.conf file setting.
- -V
- Print version information and exit
(ignoring other options).
- -b
- Fork a child to run in the background and exit
(daemon mode).
- -d n
- Enable debugging output at level n, where n is a positive
integer. The higher the level, the more output you will get. A value of
0 [default] disables debugging output. This option overrides the nasd.conf
file setting. When debugging is enabled, stderr is not closed by the nasd
process, and all debugging messages are written there.
- -pn
- -nopn [default]
- Enables or disables Partial Networking. Enabling Partial Networking allows
the server to start, even if the server cannot establish all of its well-known
sockets (connection points for clients), but establishes at least one.
- -config
file
- Use the config file file, instead of the default (/etc/nasd/nasd.conf).
The Network Audio System server attaches special meaning to the
following signals:
- SIGHUP
- This signal causes the server to close all existing
connections, free all resources, and restore all defaults.
- SIGTERM
- This
signal causes the server to exit cleanly.
- SIGUSR1
- This signal is used quite
differently from either of the above. When the server starts, it checks
to see if it has inherited SIGUSR1 as SIG_IGN instead of the usual SIG_DFL.
In this case, the server sends a SIGUSR1 to its parent process after it
has set up the various connection schemes.
Too numerous to list
them all.
- /tmp/.sockets/audio*
- Unix domain socket
- /usr/adm/audio*msgs
- /dev/audio
- Audio device
nas(1)
, auinfo(1)
, auplay(1)
, auctl(1)
,
nasd.conf(1)
If au dies before its clients, new clients won't be able
to connect until all existing connections have their TCP TIME_WAIT timers
expire.
The current access control support is weak at best.
Copyright
1993, Network Computing Devices, Inc.
The Network Audio System server was originally written by Greg Renda
and Dave Lemke, with large amounts of code borrowed from the sample X server.
The sample X server was originally written by Susan Angebranndt, Raymond
Drewry, Philip Karlton, and Todd Newman, from Digital Equipment Corporation,
with support from a large cast. It has since been extensively rewritten
by Keith Packard and Bob Scheifler, from MIT.
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