SIGRTMIN and SIGRTMAX

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**SIGRTMIN**
SA_SIGINFO macros
Description:	First real-time signal
Default action:	Abnormal termination of the process
None

**SIGRTMAX**
SA_SIGINFO macros
Description:	Last real-time signal
Default action:	Abnormal termination of the process
None

On POSIX-compliant platforms, SIGRTMIN through SIGRTMAX are signals sent to computer programs for user-defined purposes. The symbolic constants for SIGRTMIN and SIGRTMAX are defined in the header file signal.h. Symbolic signal names are used because signal numbers can vary across platforms.

[edit] Etymology

SIG is a common prefix for signal names. RTMIN is an abbreviation for real-time minimum; RTMAX is an abbreviation for real-time maximum.

[edit] Usage

The real-time signals, ranging from SIGRTMIN to SIGRTMAX, are a set of signals that can be used for application-defined purposes.

Because SIGRTMIN may have different values on different Unix-like systems, applications should always refer to the signals in the form SIGRTMIN+n, where n is a constant integer expression.

The real-time signals have a number of properties that differentiate them from other signals and make them suitable for application-defined purposes:

Multiple instances of a real-time signal can be sent to a process and all will be delivered.
Real-time signals can be accompanied by an integer or pointer value.
Real-time signals are guaranteed to be delivered in the order they were emitted.

On Linux 2.6, LinuxThreads uses the first three real-time signals, so threaded applications that support LinuxThreads should not use these signals for their own purposes.

POSIX Signals