alarm(3)
Name
alarm − schedule signal after specified time
Syntax
#include <unistd.h>
unsigned alarm(seconds)
unsigned seconds;
Description
The alarm subroutine causes signal SIGALRM, see signal(,), to be sent to the invoking process in a number of seconds given by the argument. Unless caught or ignored, the signal terminates the process.
The alarm requests are not stacked. Successive calls reset the alarm clock. If the argument is 0, any alarm request is canceled. Because of scheduling delays, resumption of execution of when the signal is caught may be delayed an arbitrary amount. The longest specifiable delay time is 100000000 seconds. Values larger than 100000000 will be silently rounded down to 100000000.
The return value is the amount of time previously remaining in the alarm clock.
Environment
When your program is compiled using the System V environment, alarm rounds up any positive fraction of a second to the next second.
When your program is compiled using the POSIX environment, alarm takes a parameter of type unsigned, and returns a value of type unsigned.