There is assertion when specify iface=PCM or iface=PCM,name='' when using amixer -c0 cget
according to the synthax
[[iface=<iface>,][name='name',][index=<index>,][device=<device>,][subdevice=<subdevice>]]|[numid=<numid>]
amixer -c0 cget iface=PCM amixer: control.c:258: snd_ctl_elem_info: Assertion `ctl && info && (info->id.name[0] || info->id.numid)' failed. Aborted
amixer -c0 cget iface=PCM,name='' amixer: control.c:258: snd_ctl_elem_info: Assertion `ctl && info && (info->id.name[0] || info->id.numid)' failed. Aborted
amixer -c0 cget Specify a full control identifier: [[iface=<iface>,][name='name',][index=<index>,][device=<device>,][subdevice=<subdevice>]]|[numid=<numid>]
amixer -c0 cget iface=PCM,name='ILD' amixer: Cannot find the given element from control hw:0
amixer -c0 cget iface=PCM,name='ILD',device=2 numid=45,iface=PCM,name='ILD',device=2 ; type=INTEGER,access=rw------,values=2,min=0,max=2147483647,step=0 : values=0,0