<s>
In	O
the	B-Language
C	I-Language
Standard	I-Language
Library	I-Language
,	O
signal	O
processing	O
defines	O
how	O
a	O
program	O
handles	O
various	O
signals	B-Operating_System
while	O
it	O
executes	O
.	O
</s>
<s>
A	O
signal	O
can	O
report	O
some	O
exceptional	O
behavior	O
within	O
the	O
program	O
(	O
such	O
as	O
division	B-Algorithm
by	I-Algorithm
zero	I-Algorithm
)	O
,	O
or	O
a	O
signal	O
can	O
report	O
some	O
asynchronous	O
event	O
outside	O
the	O
program	O
(	O
such	O
as	O
someone	O
striking	O
an	O
interactive	B-General_Concept
attention	I-General_Concept
key	I-General_Concept
on	O
a	O
keyboard	O
)	O
.	O
</s>
<s>
The	O
C	O
standard	O
defines	O
only	O
6	O
signals	B-Operating_System
.	O
</s>
<s>
They	O
are	O
all	O
defined	O
in	O
signal.h	B-Language
header	O
(	O
csignal	B-Language
header	O
in	O
C++	B-Language
)	O
:	O
</s>
<s>
SIGINT	B-General_Concept
–	O
"	O
interrupt	O
"	O
,	O
interactive	O
attention	O
request	O
sent	O
to	O
the	O
program	O
.	O
</s>
<s>
SIGSEGV	B-Error_Name
–	O
"	O
segmentation	B-Error_Name
violation	I-Error_Name
"	O
,	O
invalid	O
memory	O
access	O
.	O
</s>
<s>
Additional	O
signals	B-Operating_System
may	O
be	O
specified	O
in	O
the	O
signal.h	B-Language
header	O
by	O
the	O
implementation	O
.	O
</s>
<s>
For	O
example	O
,	O
Unix	B-Application
and	O
Unix-like	B-Operating_System
operating	I-Operating_System
systems	I-Operating_System
(	O
such	O
as	O
Linux	B-Application
)	O
define	O
more	O
than	O
15	O
additional	O
signals	B-Operating_System
;	O
see	O
Unix	B-General_Concept
signal	I-General_Concept
.	O
</s>
<s>
It	O
's	O
platform-dependent	O
and	O
may	O
be	O
used	O
on	O
Unix-like	B-Operating_System
operating	I-Operating_System
systems	I-Operating_System
.	O
</s>
<s>
A	O
signal	B-Operating_System
handler	I-Operating_System
is	O
a	O
function	O
which	O
is	O
called	O
by	O
the	O
target	O
environment	O
when	O
the	O
corresponding	O
signal	O
occurs	O
.	O
</s>
<s>
The	O
target	O
environment	O
suspends	O
execution	O
of	O
the	O
program	O
until	O
the	O
signal	B-Operating_System
handler	I-Operating_System
returns	O
or	O
calls	O
longjmp( )	O
.	O
</s>
<s>
Signal	B-Operating_System
handlers	I-Operating_System
can	O
be	O
set	O
with	O
signal( )	O
or	O
sigaction( )	O
.	O
</s>
<s>
Signal	B-Operating_System
handlers	I-Operating_System
can	O
be	O
specified	O
for	O
all	O
but	O
two	O
signals	B-Operating_System
(	O
SIGKILL	B-General_Concept
and	O
SIGSTOP	B-General_Concept
cannot	O
be	O
caught	O
,	O
blocked	O
or	O
ignored	O
)	O
.	O
</s>
<s>
If	O
the	O
signal	O
reports	O
an	O
error	O
within	O
the	O
program	O
(	O
and	O
the	O
signal	O
is	O
not	O
asynchronous	O
)	O
,	O
the	O
signal	B-Operating_System
handler	I-Operating_System
can	O
terminate	O
by	O
calling	O
abort( )	O
,	O
exit( )	O
,	O
or	O
longjmp( )	O
.	O
</s>
