table of contents
ALSACTL_INIT(7) | alsactl init | ALSACTL_INIT(7) |
NAME¶
alsactl_init - alsa control management - initializationDESCRIPTION¶
"alsactl init" provides soundcard specific initialization.CONFIGURATION¶
All "alsactl init" configuration files are placed in /usr/share/alsa/init/ directory. The top level configuration file is /usr/share/alsa/init/00main. The default top-level file can be also specified using -i or --initfile parameter for the alsactl tool. Every file consists of a set of lines of text. All empty lines or lines beginning with '#' will be ignored.Rules files¶
The "alsactl init" rules are read from the files located in the /usr/share/alsa/init/*. The top level configuration file is /usr/share/alsa/init/00main. Every line in the rules file contains at least one key value pair. There are two kind of keys, match and assignment keys. If all match keys are matching against its value, the rule gets applied and the assign keys get the specified value assigned. A rule may consists of a list of one or more key value pairs separated by a comma. Each key has a distinct operation, depending on the used operator. Valid operators are: ==Compare for equality.
!=
Compare for non-equality.
=
Assign a value to a key. Keys that represent a
list, are reset and only this single value is assigned.
+=
Add the value to a key that holds a list of
entries.
:=
Assign a value to a key finally; disallow any
later changes, which may be used to prevent changes by any later rules.
The following key names can be used to match against device properties:
CARDINDEX
Match the card index of the ALSA driver.
CTL{attribute}
Set or test universal control attribute.
Possible attributes:
numid
CONFIG{sysfs_device}
Numeric control identification.
iface, interface
Control interface name (CARD, HWEDEP, MIXER,
PCM, RAWMIDI, TIMER, SEQUENCER)
subdev, subdevice
Subdevice number.
name
Control name
index
Control index
type
Control type (BOOLEAN, INTEGER, INTEGER64,
ENUMERATED, BYTES, IEC958)
attr, attribute
Attributes (stored in a string - use match
characters * and ?):
r
owner
control is readable
w
control is writable
v
control is volatile
i
control is inactive
l
control is locked
R
control is TLV readable
W
control is TLV writable
C
control is TLV commandable
o
process is owner of this control
u
control created in user space
Control owner process PID number
count
Control count of values
min
Value range - minimum value
max
Value range - maximum value
step
Value range - step value
dBmin
Value range - minimum dB value
dBmax
Value range - maximum dB value
items
Enumerated value - number of text items
enums
Enumerated value - list of text names stored
between '|' character
value
Value of control stored to a string delimited
by comma (,).
do_search
Search for a control. Value "1" is
returned if a control was found. The CTL{name} key might contain match
characters * and ?. An control index might be specified as first argument
starting from zero (e.g. CTL{do_search 2}="1").
do_count
Search for a controls and return total count
of matched ones. The CTL{name} key might contain match characters * and
?.
The relative path to sysfs subsystem
specifying the root directory of a soundcard device. Usually, it should be set
to "/class/sound/card$cardinfo{card}/device".
ATTR{filename}
Match sysfs attribute values of the soundcard
device. The relative path to sysfs tree must be defined by
CONFIG{sysfs_device} key. Trailing whitespace in the attribute values is
ignored, if the specified match value does not contain trailing whitespace
itself. Depending on the type of operator, this key is also used to set the
value of a sysfs attribute.
ENV{key}
Match against the value of an environment
variable. Up to five ENV keys can be specified per rule. Depending on
the type of operator, this key is also used to export a variable to the
environment.
PROGRAM
Execute external program. The key is true, if
the program returns without exit code zero. The whole event environment is
available to the executed program. The program's output printed to stdout is
available for the RESULT key.
Several buildin commands are available:
__ctl_search
RESULT
Search for a control. The CTL{name} key might
contain match characters * and ?. An control index might be specified as first
argument starting from zero (e.g. PROGRAM="__ctl_search 2").
__ctl_count
Search for a controls and return total count
of matched ones. The CTL{name} key might contain match characters * and
?.
Match the returned string of the last PROGRAM
call. This key can be used in the same or in any later rule after a PROGRAM
call.
Most of the fields support a shell style pattern matching. The following pattern
characters are supported:
*
Matches zero, or any number of
characters.
?
Matches any single character.
[]
Matches any single character specified within
the brackets. For example, the pattern string 'tty[SR]' would match either
'ttyS' or 'ttyR'. Ranges are also supported within this match with the '-'
character. For example, to match on the range of all digits, the pattern [0-9]
would be used. If the first character following the '[' is a '!', any
characters not enclosed are matched.
The following keys can get values assigned:
CTL{numid}, CTL{iface}, CTL{device}, CTL{subdev},
CTL{name}, CTL{index},
Select universal control element.
CTL{value}
Value is set (written) also to soundcard's
control device and RESULT key is set to errno code. The result of set
operation is always true (it means continue with next key on line).
CTL{values}
Value is set (written) also to soundcard's
control device (all control values are set to specified value) and RESULT key
is set to errno code. The result of set operation is always true (it means
continue with next key on line).
CTL{write}
Value is set (written) also to soundcard's
control device (all control values are set to specified value). The result of
set operation is true when operation succeed (it means continue with next key
on line).
ENV{key}
Export a variable to the environment.
Depending on the type of operator, this key is also to match against an
environment variable.
RESULT
Set RESULT variable. Note that PROGRAM also
sets this variable, but setting this variable manually might be useful to
change code execution order (included files).
LABEL
Named label where a GOTO can jump to.
GOTO
Jumps to the next LABEL with a matching name.
The goto cannot jump backward.
INCLUDE
Include specified filename or all files in
specified directory
ACCESS
Check if specified file or directory
exists
CONFIG{sysfs_device}
The relative path to sysfs subsystem
specifying the root directory of a soundcard device. Usually, it should be set
to "/class/sound/card$cardinfo{card}/device".
PRINT
PRINT value to stdout.
ERROR
PRINT value to stderr.
EXIT
Exit immediately and set program exit code to
value (should be integer). If value is "return" string, parser
leaves current included file and returns to parent configuration file.
The PROGRAM, RESULT, CTL{value}, PRINT,
ERROR, EXIT, CONFIG{} fields support simple printf-like
string substitutions. It allows the use of the complete environment set by
earlier matching rules. For all other fields, substitutions are applied while
the individual rule is being processed. The available substitutions are:
$cardinfo{attribute},
%i{attribute }
See CARDINFO{} for more details.
$ctl{attribute},
%C{attribute}
See CTL{} for more details.
$attr{file}, %s{file}
The value of a sysfs attribute found at the
device, where all keys of the rule have matched. If the attribute is a
symlink, the last element of the symlink target is returned as the
value.
$env{key}, %E{key}
The value of an environment variable.
$result, %c
The string returned by the external program
requested with PROGRAM. A single part of the string, separated by a space
character may be selected by specifying the part number as an attribute:
%c{N}. If the number is followed by the '+' char this part plus all
remaining parts of the result string are substituted: %c{N+}
$sysfsroot, %r
Root directory where sysfs file-system is
mounted. Ususally, this value is just "/sys".
$config{key}, %g{key}
The value of a configuration variable. See
CONFIG{} for more details.
%%
The '%' character itself.
$$
The '$' character itself.
The count of characters to be substituted may be limited by specifying the
format length value. For example, '%3s{file}' will only insert the first three
characters of the sysfs attribute
AUTHOR¶
Written by Jaroslav Kysela perex@perex.cz Some portions are written by Greg Kroah-Hartman greg@kroah.com and Kay Sievers kay.sievers@vrfy.org.SEE ALSO¶
alsactl(1)July 2008 | alsactl |