Certain POSIX signals do not go through the condition handling
steps described above:
- SIGKILL and SIGSTOP cannot be caught or ignored; they always take
effect.
- SIGCONT immediately begins all stopped threads in a process if
SIG_DFL is set.
- SIGTTIN, SIGTTOU, and SIGSTP immediately stop all threads in a
process if SIG_DFL is set.
IBM® extensions to POSIX signals
that do not go through condition handing:
- SIGDUMP cannot be caught or ignored; it always takes effect.
- SIGTHSTOP and SIGTHCONT cannot be caught or ignored; they always
take effect.