PROLOG<\/a> This manual page is part of the POSIX Programmer\u2019s Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.<\/p>\n signal \u2014 signal management<\/p>\n #include void (*signal(int sig<\/i>, void (*func<\/i>)(int)))(int);<\/p>\n The functionality described on this reference page is aligned with the ISO\u00a0C standard. Any conflict between the requirements described here and the ISO\u00a0C standard is unintentional. This volume of POSIX.1-2017 defers to the ISO\u00a0C standard.<\/p>\n The signal<\/i>() function chooses one of three ways in which receipt of the signal number sig<\/i> is to be subsequently handled. If the value of func<\/i> is SIG_DFL, default handling for that signal shall occur. If the value of func<\/i> is SIG_IGN, the signal shall be ignored. Otherwise, the application shall ensure that func<\/i> points to a function to be called when that signal occurs. An invocation of such a function because of a signal, or (recursively) of any further functions called by that invocation (other than functions in the standard library), is called a \u2018\u2018signal handler\u2019\u2019.<\/p>\n When a signal occurs, and func<\/i> points to a function, it is implementation-defined whether the equivalent of a:<\/p>\n signal(sig<\/i>, SIG_DFL);<\/p>\n is executed or the implementation prevents some implementation-defined set of signals (at least including sig<\/i>) from occurring until the current signal handling has completed. (If the value of sig<\/i> is SIGILL, the implementation may alternatively define that no action is taken.) Next the equivalent of:<\/p>\n (*func)(sig);<\/p>\n is executed. If and when the function returns, if the value of sig<\/i> was SIGFPE, SIGILL, or SIGSEGV or any other implementation-defined value corresponding to a computational exception, the behavior is undefined. Otherwise, the program shall resume execution at the point it was interrupted. The ISO\u00a0C standard places a restriction on applications relating to the use of raise<\/i>() from signal handlers. This restriction does not apply to POSIX applications, as POSIX.1-2008 requires raise<\/i>() to be async-signal-safe (see Section 2.4.3<\/i>, Signal Actions<\/i>).<\/p>\n If the process is multi-threaded, or if the process is single-threaded and a signal handler is executed other than as the result of:<\/p>\n
NAME<\/a>
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DESCRIPTION<\/a>
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EXAMPLES<\/a>
APPLICATION USAGE<\/a>
RATIONALE<\/a>
FUTURE DIRECTIONS<\/a>
SEE ALSO<\/a>
COPYRIGHT<\/a> <\/p>\n
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