sighold(2)
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sighold System Call
Add a signal to the calling process's set of blocked signals.
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SYNTAX
#include <signal.h>
int sighold (signal_number)
int signal_number;
PARAMETERS
signal_number The signal to be blocked.
DESCRIPTION
Sighold adds the specified signal to the calling process's set of
signals blocked from presentation. If the specified signal is
already blocked, no error is reported, but this call has no
effect as block operations do not nest.
It is not possible to block SIGKILL, SIGSTOP, or SIGCONT. It may
or may not be possible to block signals that are not defined by
the system. An attempt to block these signals will produce the
error EINVAL.
Note that this system call performs exactly the same basic
operation as the system call 'sigset' with the function parameter
set to SIG_HOLD and as the system call 'sigblock' with a mask
specifying a single signal. These three system calls differ in
their return values and in reporting attempts to block a signal
that cannot be blocked.
ACCESS CONTROL
None.
RETURN VALUE
0 The operation succeeded.
-1 The operation failed.
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sighold(2)
EXCEPTIONS
Errno may be set to the following error code:
EINVAL <Signal_number> is an illegal signal number or one
which may not be blocked.
SEE ALSO
The related system calls: sigset, sighold, sigrelse, sigignore,
sigpause
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