Writing udev rules for handling CP special messages

change events

The smsgiucv_app device driver generates change uevents for each CP special message that is received.

For example, the special message:

#CP SMSG LXGUEST1 APP THIS IS A TEST MESSAGE

might trigger the following uevent:

UEVENT[1263487666.708881] change /devices/iucv/smsgiucv_app (iucv)
ACTION=change
DEVPATH=/devices/iucv/smsgiucv_app
SUBSYSTEM=iucv
SMSG_SENDER=MAINT
SMSG_ID=APP
SMSG_TEXT=THIS IS A TEST MESSAGE
DRIVER=SMSGIUCV
SEQNUM=1493

add and remove events

In addition to the change event for received CP special messages, generic add and remove events are generated when the module is loaded or unloaded, for example:

UEVENT[1263487583.511146] add /module/smsgiucv_app (module)
ACTION=add
DEVPATH=/module/smsgiucv_app
SUBSYSTEM=module
SEQNUM=1487

UEVENT[1263487583.514622] add /devices/iucv/smsgiucv_app (iucv)
ACTION=add
DEVPATH=/devices/iucv/smsgiucv_app
SUBSYSTEM=iucv
DRIVER=SMSGIUCV
SEQNUM=1488

UEVENT[1263487628.955149] remove /devices/iucv/smsgiucv_app (iucv)
ACTION=remove
DEVPATH=/devices/iucv/smsgiucv_app
SUBSYSTEM=iucv
SEQNUM=1489

UEVENT[1263487628.957082] remove /module/smsgiucv_app (module)
ACTION=remove
DEVPATH=/module/smsgiucv_app
SUBSYSTEM=module
SEQNUM=1490

With the information from the uevents, you can create custom udev rules to trigger actions that depend on the settings of the SMSG_* environment variables.

For your udev rules, use the add and remove uevents to initialize and clean up resources. To handle CP special messages, write udev rules that match change uevents. For more information about writing udev rules, see the udev man page.