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Ïà¹Øº¯Êý   signal£¬sleep
±íÍ·Îļþ   #include<unistd.h>
¶¨Ò庯Êý   unsigned int alarm(unsigned int seconds);
º¯Êý˵Ã÷   alarm()ÓÃÀ´ÉèÖÃÐźÅSIGALRMÔÚ¾­¹ý²ÎÊýsecondsÖ¸¶¨µÄÃëÊýºó´«Ë͸øÄ¿Ç°µÄ½ø³Ì¡£Èç¹û²ÎÊýseconds Ϊ0£¬Ôò֮ǰÉèÖõÄÄÖÖӻᱻȡÏû£¬²¢½«Ê£ÏµÄʱ¼ä·µ»Ø¡£
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·¶Àý   #include<unistd.h>
#include<signal.h>
void handler() {
printf(“hello\n”);
}
main()
{
int i;
signal(SIGALRM,handler);
alarm(5);
for(i=1;i<7;i++){
printf(“sleep %d ...\n”,i);
sleep(1);
}
}
Ö´ÐР  sleep 1 ...
sleep 2 ...
sleep 3 ...
sleep 4 ...
sleep 5 ...
hello
sleep 6 ...
kill£¨´«ËÍÐźŸøÖ¸¶¨µÄ½ø³Ì£©  
Ïà¹Øº¯Êý   raise£¬signal
±íÍ·Îļþ   #include<sys/types.h>
#include<signal.h>
¶¨Ò庯Êý   int kill(pid_t pid,int sig);
º¯Êý˵Ã÷   kill()¿ÉÒÔÓÃÀ´ËͲÎÊýsigÖ¸¶¨µÄÐźŸø²ÎÊýpidÖ¸¶¨µÄ½ø³Ì¡£²ÎÊýpidÓм¸ÖÖÇé¿ö:
pid>0 ½«ÐźŴ«¸ø½ø³Ìʶ±ðÂëΪpid µÄ½ø³Ì¡£
pid=0 ½«ÐźŴ«¸øºÍÄ¿Ç°½ø³ÌÏàͬ½ø³Ì×éµÄËùÓнø³Ì
pid=-1 ½«ÐźŹ㲥´«Ë͸øϵͳÄÚËùÓеĽø³Ì
pid<0 ½«ÐźŴ«¸ø½ø³Ì×éʶ±ðÂëΪpid¾ø¶ÔÖµµÄËùÓнø³Ì
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EPERM ȨÏÞ²»¹»ÎÞ·¨´«ËÍÐźŸøÖ¸¶¨½ø³Ì
·¶Àý   #include<unistd.h>
#include<signal.h>
#include<sys/types.h>
#include<sys/wait.h>
main()
{
pid_t pid;
int status;
if(!(pid= fork())){
printf(“Hi I am child process!\n”);
sleep(10);
return;
}
else{
printf(“send signal to child process (%d) \n”,pid);
sleep(1);
kill(pid ,SIGABRT);
wait(&status);
if(WIFSIGNALED(status))
printf(“chile process receive signal %d\n”,WTERMSIG(status));
}
}
Ö´ÐР  sen signal to