把他的程式重新改動一下，改為一次性為訊號集合申請兩個訊號量：
**變成：
#include #include#include
#include
#include
#define lock -1
#define unlock 1
/*semophore operation (lock/unlock)
*/void semop01(int semid,int
op);
/*semophore operation (lock/unlock)
*/void semop02(int semid,int
op);
intmain()
ctl_arg;
char *file01 = "
./sem01.txt
";
intchild_cnt01;
intline_cnt01;
if ((fp01 = fopen(file01,"
w")) ==null)
setvbuf(fp01,null,_ionbf,
0);
char *file02 = "
./sem02.txt
";
intchild_cnt02;
intline_cnt02;
if ((fp02 = fopen(file02,"
w")) ==null)
setvbuf(fp02,null,_ionbf,
0);
/*to create one semophore array which hold two semophore
*/if ((semid = semget(ipc_private,2,0600)) == -1)/*
initialize the first semophore with value 1
*/ctl_arg.val = 1
;
if (semctl(semid,0,setval,ctl_arg) == -1
)
/*initialize the second semophore with value 1
*/ctl_arg.val = 1
;
if (semctl(semid,1,setval,ctl_arg) == -1
)
/*fork three child process
*/for (child_cnt01 = 0; child_cnt01 < 3; ++child_cnt01)
semop01(semid,unlock);
/*unlock
*/printf(
"child process %d ends\n
",child_cnt01 + 1
); exit(exit_success);
}
}
/*fork another two child process
*/for (child_cnt02 = 0; child_cnt02< 2; ++child_cnt02)
semop02(semid,unlock);
/*unlock
*/printf(
"another child process %d ends\n
",child_cnt02 + 1
); exit(exit_success);
}
}
/*parent process, waitint for child process ending
*/for (child_cnt01 = 0; child_cnt01 < 5; ++child_cnt01)
/*delete semophore array
*/if (semctl(semid,0,ipc_rmid,ctl_arg) == -1
)
fclose(fp01);
fclose(fp02);
printf(
"parenet process ends\n
");
return
exit_success;
}
/*semophore operation (lock/unlock)
*/void semop01(int p_semid,int
p_op)
return
;
}
/*semophore operation (lock/unlock)
*/void semop02(int p_semid,int
p_op)
return
;
}
其中，三個子程序用第乙個訊號量，另外兩個子程序用第二個訊號量。互不干擾。
執行結果：
child process 1 begin
child process 2 begin
child process 3 begin
another child process 1 begin
another child process 2 begin
child process 1 ends
another child process 1 ends
child process 2 ends
another child process 2 ends
child process 3 ends
parenet process ends
檔案內容：
[root@gaorhel01 gao]# cat sem01.txt
child process 1 msg : 1
child process 1 msg : 2
child process 1 msg : 3
child process 1 msg : 4
child process 1 msg : 5
child process 2 msg : 1
child process 2 msg : 2
child process 2 msg : 3
child process 2 msg : 4
child process 2 msg : 5
child process 3 msg : 1
child process 3 msg : 2
child process 3 msg : 3
child process 3 msg : 4
child process 3 msg : 5
[root@gaorhel01 gao]# cat sem02.txxt
cat: sem02.txxt: no such file or directory
[root@gaorhel01 gao]# cat sem02.txt
another child process 1 msg : 1
another child process 1 msg : 2
another child process 1 msg : 3
another child process 1 msg : 4
another child process 1 msg : 5
another child process 2 msg : 1
another child process 2 msg : 2
another child process 2 msg : 3
another child process 2 msg : 4
another child process 2 msg : 5
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