The CUPS notifier interface provides a standard method for adding support for
new event notification methods to CUPS. Each notifier delivers one or more IPP
events from the standard input to the specified recipient.
Notifiers must read IPP messages from the standard input using the
ippNew and ippReadFile functions and exit on error. Notifiers are encouraged to
exit after a suitable period of inactivity, however they may exit after reading
the first message or stay running until an error is seen.
Messages sent to stderr are generally logged to the current ErrorLog.
Each line begins with a standard prefix:
ALERT: message
Sets the printer-state-message attribute and adds the specified
message to the current ErrorLog using the "alert" log level.
CRIT: message
Sets the printer-state-message attribute and adds the specified
message to the current ErrorLog using the "critical" log level.
DEBUG: message
Sets the printer-state-message attribute and adds the specified
message to the current ErrorLog using the "debug" log level.
DEBUG2: message
Sets the printer-state-message attribute and adds the specified
message to the current ErrorLog using the "debug2" log level.
EMERG: message
Sets the printer-state-message attribute and adds the specified
message to the current ErrorLog using the "emergency" log level.
ERROR: message
Sets the printer-state-message attribute and adds the specified
message to the current ErrorLog using the "error" log level.
INFO: message
Sets the printer-state-message attribute. If the current LogLevel
is set to "debug2", also adds the specified message to the
current ErrorLog using the "info" log level.
NOTICE: message
Sets the printer-state-message attribute and adds the specified
message to the current ErrorLog using the "notice" log level.
WARNING: message
Sets the printer-state-message attribute and adds the specified
message to the current ErrorLog using the "warning" log level.