Working with the Unix OS

Processes II
{
}
char process_name[MAXLEN];
char line[MAXLEN];
sprintf(process_name, "parent");
while (1) {
printf("%s> ",process_name);
fgets(line, MAXLEN, stdin);
if (strcmp(line, "dir") == 0)
directory(process_name);
else if (strcmp(line, "start") == 0)
start(process_name);
else if (strcmp(line, "exit") == 0)
exit(0) ;
else if (strcmp(line, "") == 0)
continue;
else
printf("there is no help yet\n");
}
directory(char *pname)
{
int fd, nread,size;
char *dname,*path;
static struct dirent dlink;
getpath(pname, path);
}
if ((fd=open(path, 0)) == -1) {
fprintf(stderr, "no such directory\n");
exit(1);
}
dlink.d_name[DIRSIZ] = '\0';
size = sizeof(struct dirent);
while((nread=read(fd, &dlink, size)) == size)
if (dlink.d_ino != 0){}
Interprocess Communication
- IPC between two processes on a single system
user
process
user
process
kernel
- IPC between two processes on different systems
user
process
user
process
kernel
kernel
There are several ways to implement IPCs:
- Pipes
- FIFOs
- message queues
- semaphores
- shared memory
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