进程间通信的system v信号量

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1. 
   
2.     (1)semcreate.c  [color=Red]/创建一个信号量集/[/color]
   
3. 
   
4. #include<stdlib.h>
   
5. #include<stdio.h>
   
6. #include<sys/sem.h>
   
7. #include<unistd.h>
   
8. #include<sys/types.h>
   
9. int main(int argc,char **argv)
   
10. {
    
11.     int c,oflag,semid,nsems;
    
12. 
    
13.     oflag=0644|IPC_CREAT;
    
14.     while((c=getopt(argc,argv,"e"))!=-1)
    
15.     {
    
16.         switch(c)
    
17.         {
    
18.             case 'e':
    
19.                 oflag|=IPC_EXCL;
    
20.                 printf("create faile :exist\n");
    
21.                 break;
    
22.         }
    
23.     }
    
24.     if(optind!=argc-2)
    
25.         printf("usage:semcreate[-e]<pathname><nsems>\n");
    
26.      nsems=atoi(argv[optind+1]);
    
27.         printf("nsems=%d\n",nsems);
    
28.     semid=semget(ftok(argv[optind],0),nsems,oflag);
    
29.     printf("semid=%d\n",semid);
    
30.     exit(0);
    
31. }
    
32.    (2)semrmid.c  [color=Red]/*删除一个信号量集*/[/color]
    
33. #include<stdio.h>
    
34. #include<stdlib.h>
    
35. #include<sys/sem.h>
    
36. int main(int argc,char **argv)
    
37. {
    
38.     int semid;
    
39.    if(argc!=2)
    
40.         printf("usage:semrid<pathname>");
    
41.     semid=semget(ftok(argv[1],0),0,0);
    
42.     semctl(semid,0,IPC_RMID);
    
43.     exit(0);
    
44. }
    
45. (3)semsetvalues.c /*设置信号量集用元素的值*/
    
46. #include<stdio.h>
    
47. #include<unistd.h>
    
48. #include<sys/sem.h>
    
49. #include<stdlib.h>
    
50. union semun
    
51. {
    
52.     int val;
    
53.     struct semid_ds *buf;
    
54.     unsigned short *array;
    
55. };
    
56. int main(int argc,char **argv)
    
57. {
    
58.     int semid,nsems,i;
    
59.     struct semid_ds seminfo;
    
60.     unsigned short *ptr;
    
61.     union semun arg;
    
62. 
    
63.     if(argc<2)
    
64.         printf("usage:semsetvalues<pathname>[values...]\n");
    
65.     semid=semget(ftok(argv[1],0),0,0);
    
66.      printf("semid=%d\n",semid);
    
67.         arg.buf=&seminfo;
    
68.     semctl(semid,0,IPC_STAT,arg);
    
69.     nsems=arg.buf->sem_nsems;
    
70.    
    
71.     if (argc!=nsems+2)
    
72.         printf("%d semaphores in set,%d values specified",nsems,argc-2);
    
73.     ptr=calloc(nsems,sizeof(unsigned short));
    
74.     arg.array=ptr;
    
75.     for(i=0;i<nsems;i++)
    
76.         ptr[i]=atoi(argv[i+2]);
    
77.     semctl(semid,0,SETALL,arg);
    
78.     exit(0);
    
79. }
    
80. (4)semsetvalues.c
    
81. #include<stdio.h>
    
82. #include<stdlib.h>
    
83. #include<sys/sem.h>
    
84. union semun
    
85. {
    
86.     int val;
    
87.     struct semid_ds *buf;
    
88.     unsigned short *array;
    
89. };
    
90. 
    
91. int main(int argc,char **argv)
    
92. {
    
93.     int semid,nsems,i;
    
94.     struct  semid_ds seminfo;
    
95.     unsigned short *ptr;
    
96.     union semun arg;
    
97.        if(argc!=2)
    
98.         printf("usage:semgetvalues<pathname>\n");
    
99.     semid=semget(ftok(argv[1],0),0,0);
    
100.     printf("semid=%d\n",semid);
     
101.        arg.buf=&seminfo;
     
102.     semctl(semid,0,IPC_STAT,arg);
     
103.     nsems=arg.buf->sem_nsems;
     
104.     ptr=calloc(nsems,sizeof(unsigned short));
     
105.     arg.array=ptr;
     
106.        semctl(semid,0,GETALL,arg);
     
107.     for(i=0;i<nsems;i++)
     
108.         printf("semval[%d]=%d\n",i,ptr[i]);
     
109.     exit(0);
     
110. }
     
111. (5)
     
112. semops.c
     
113. #include<stdlib.h>
     
114. #include<stdio.h>
     
115. #include<sys/sem.h>
     
116. #include<unistd.h>
     
117. 
     
118. int main(int argc,char **argv)
     
119. {
     
120.     int c,i,flag,semid,nops;
     
121.     struct sembuf *ptr;
     
122. 
     
123.     flag=0;
     
124.     while((c=getopt(argc,argv,"nu"))!=-1)
     
125.     {
     
126.         switch(c)
     
127.         {
     
128.             case 'n':
     
129.                 flag|=IPC_NOWAIT;
     
130.                 break;
     
131.             case 'u':
     
132.                 flag|=SEM_UNDO;
     
133.                 break;
     
134.         }
     
135.     }
     
136.     if(argc-optind<2)
     
137.         printf("usage:semops[-n][-u]<pathname>operation...");
     
138.     semid=semget(ftok(argv[optind],0),0,0);
     
139.     optind++;
     
140.     nops=argc-optind;
     
141.     ptr=calloc(nops,sizeof(struct sembuf));
     
142.     for(i=0;i<nops;i++)
     
143.     {
     
144.         ptr[i].sem_num=i;
     
145.         ptr[i].sem_op=atoi(argv[optind+1]);
     
146.         ptr[i].sem_flg=flag;
     
147.     }
     
148.     semop(semid,ptr,nops);
     
149.         exit(0);
     
150. }
     
151. 
     

复制代码

运行：

ermao@lost-desktop:~/ermao$ gcc -o semcreate semcreate.c
ermao@lost-desktop:~/ermao$ gcc -o semrmid  semrmid.c
ermao@lost-desktop:~/ermao$ gcc -o semsetvalue semsetvalue.c
ermao@lost-desktop:~/ermao$ gcc -o semgetvalues semgetvalues.c
ermao@lost-desktop:~/ermao$ gcc -o semops  semops.c
ermao@lost-desktop:~/ermao$ touch /tmp/ermao
ermao@lost-desktop:~/ermao$ ./semcreate /tmp/ermao 3
nsems=3
semid=32769
ermao@lost-desktop:~/ermao$ ./semsetvalue /tmp/ermao 1 2 3
nsems=134514384
ermao@lost-desktop:~/ermao$ ./semgetvalues /tmp/ermao
nsems=134514315
semval[0]=1
semval[1]=2
semval[2]=3

ermao@lost-desktop:~/ermao$ ./semops -n /tmp/ermao -1 -2 -4
./semops: invalid option -- '1'问什么为负数的时候invalid的，求解释？
./semops: invalid option -- '2'
./semops: invalid option -- '4'
usage:semops[-n][-u]<pathname>operation...