ssignal(3C)ssignal(3C)NAMEssignal(), gsignal() - software signals
and implement a software facility similar to signal(5). This facility
is used by the Standard C Library to enable users to indicate the dis‐
position of error conditions, and is also made available to users for
their own purposes.
Software signals made available to users are associated with integers
in the inclusive range 1 through 15. A call to associates a procedure,
action, with the software signal sig; the software signal, sig, is
raised by a call to Raising a software signal causes the action estab‐
lished for that signal to be taken.
The first argument to is a number identifying the type of signal for
which an action is to be established. The second argument defines the
action; it is either the name of a (user-defined) action function or
one of the manifest constants (default) or (ignore). returns the
action previously established for that signal type; if no action has
been established or the signal number is illegal, returns
raises the signal identified by its argument, sig:
· If an action function has been established for sig, that
action is reset to and the action function is entered with
argument sig. returns the value returned to it by the action
· If the action for sig is returns the value 1 and takes no
· If the action for sig is returns the value 0 and takes no
· If sig has an illegal value or no action was ever specified
for sig, returns the value 0 and takes no other action.
SEE ALSOsignal(5), thread_safety(5).
Some additional signals with numbers outside the range 1 through 15 are
used by the Standard C Library to indicate error conditions. Those
signal numbers outside the range 1 through 15 are legal, although their
use may interfere with the operation of the Standard C Library.