alsactl_init man page on ElementaryOS

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ALSACTL_INIT(7)			 alsactl init		       ALSACTL_INIT(7)

NAME
       alsactl_init - alsa control management - initialization

DESCRIPTION
       "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
	       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
		   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

	   owner
	       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 ?.

       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".

       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
	       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 ?.

       RESULT
	   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 the specified filename or files in specified directory.

	   When a directory is specified, only the files with the extension
	   ".conf" are read. Also they are read in the alphabetical order.
	   Thus it's highly recommended to use some number prefix (e.g.
	   "01-something.conf") to assure the order of execucions.

       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)

alsactl				   July 2008		       ALSACTL_INIT(7)
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