$sig

Signal number that caused the event 

$sigstr

Name of $sig 

$sigcode

Subcode of $sig if applicable 

$sigcodestr

Name of $sigcode 

$sigsender

Process id of sender of the signal, if appropriate 

$exitcode

Value of the argument passed to _exit(2) or exit(3) or the return value of main 

$dlobj

Pathname of the load object dlopened or dlclosed 

$syscode

System call number 

$sysname

System call name 

$reason

One of signal, exit, kill, or detach