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|
#!/bin/sh
#
# volmon -- Panel applet to monitor ALSA mixer volume
#
# Copyright (C) 2018 Patrick "P. J." McDermott
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be included
# in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
# IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
# CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
# TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
# SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
set -eu
# Default values, overridden in ~/.config/panel/volmonrc
scontrol='Master,0'
db_format_on='%3.0f'
db_format_off='off'
output='dB Vol:\n${Front_Left} ${Front_Right}\n${Side_Left} ${Side_Right}\n'
output="${output}"'${Rear_Left} ${Rear_Right}\n'
volmon()
{
local pb_bre=
local channel_var=
local db_vol=
local on_off=
local vol_str=
pb_bre='^ \([^:][^:]*\): Playback [0-9][0-9]* \[[0-9][0-9]*%\]'
pb_bre="${pb_bre}"' \[\(-*[0-9][0-9]*.[0-9][0-9]\)dB\] \[\(o[nf]*\)\]$'
while :; do
if ! read -r channel_var; then
break
fi
if ! read -r db_vol on_off; then
break
fi
case "${on_off}" in
'on')
vol_str="$(printf "${db_format_on}" ${db_vol})"
;;
'off')
vol_str="$(printf "${db_format_off}" ${db_vol})"
;;
esac
eval "${channel_var}=\"\${vol_str}\""
done <<-EOF
$(amixer get "${scontrol}" | sed -n "
/${pb_bre}/{ # Playback channel lines.
h; # Save original line.
s/${pb_bre}/\1/; # Extract channel name.
s/[^A-Za-z0-9]/_/g; # Make safe for var name.
p; # And print it.
g; # Restore original line.
s/${pb_bre}/\2 \3/; # Extract volume and mute.
p; # And print it.
};")
EOF
eval "printf \"${output}\""
return 0
}
usage()
{
printf 'Usage: %s\n' "${0}"
return 0
}
main()
{
if [ ${#} -ne 0 ]; then
usage 1>&2
return 1
fi
# POSIX on the dot utility:
# "If no readable file is found, a non-interactive shell shall abort"
# So to survive an ENOENT or other error, we need this eval/cat command.
eval "$(cat ~/.config/panel/volmonrc 2>/dev/null || :)"
volmon
return 0
}
main "${@}"
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