p The return value of .Fn signalname is .Dv NULL if .Fa sig does not represent a valid signal number, or if the signal number given has no name.
p The .Fn signalnumber function converts the signal name .Fa name to the number corresponding to that signal. The .Fa name is handled in a case-insensitive manner. Any leading .Dq Dv SIG prefix in .Fa name is ignored.
p This implementation also accepts .Dv rtmax Ns [-n] and .Dv rtmin Ns [+n]
o where the optional .Ar n is a decimal integer between 0 and SIGRTMAX-SIGRTMIN
c to refer to the real time signals.
p The .Fn signalnumber function returns the signal number, or zero (0) if the name given does not represent a valid signal.
p The .Fn signalnext function takes a signal number, and returns the number of the next available bigger signal number. When no higher signal numbers remain, it returns zero (0). The parameter .Fa sig can be given as zero (0), to obtain the smallest implemented signal number.
p The .Fn signalnext function returns minus one (-1) on error, that is, if the given signal .Fa sig is neither a valid signal number nor zero. It returns zero when the input signal number, .Fa sig , is the biggest available signal number. Otherwise it returns the signal number of an implemented signal that is larger than .Fa sig and such that there are no implemented signals with values between .Fa sig and the value returned.
p The .Fn signalnext function can also be used to determine if a non-zero signal number is valid or not (0 is always invalid, but cannot be detected as such this way.) Given the non-zero signal number to check as .Fa sig , if .Fn signalnext returns anything other than minus one (-1) then .Fa sig represents a valid signal number. If the return value is -1 then .Fa sig is invalid. .Sh SEE ALSO .Xr kill 1 , .Xr intro 2 , .Xr psignal 3 , .Xr strsignal 3 .Sh HISTORY The .Fn signalname , .Fn signalnext , and .Fn signalnumber functions first appeared in .Nx 8.0 .