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User-Added Signals

Restrictions on Synchronous and Asynchronous Signals

User signals can be synchronous or asynchronous; you can define as many as eight of each type. Synchronous signals generally must be handled immediately, while asynchronous signals either do not need to be handled immediately or cannot be handled immediately for technical reasons.

Synchronous signals must be assigned one of the signal numbers defined by the symbols SIGUSR1 through SIGUSR8. Asynchronous signals must be assigned one of the signal numbers defined by the symbols SIGASY1 through SIGASY8. When you write the routine to define the signal, you can rename it to have a more useful and mnemonic name.

There are no special requirements for defining asynchronous signals. Additional considerations may apply, however, when defining asynchronous signals for programs that use pause , sigpause , sigsuspend , or sleep ; refer to the description of the ECBPP field of ZENQARGS in Routine for Asynchronous Signals: L$CZENQ.

The following list describes the requirements for defining a signal as synchronous.


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