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ไปที่ Terminal
เปิด Terminal
ติดตั้ง C/C++ Compiler
sudo apt install build-essentialพิมพ์ y แล้ว Enter 
ทำการ Check ว่า C/C++ Compiler ติดตั้งสมบูรณ์มั๊ยด้วย
gccg++ดูได้จากรูป
สร้างไฟล์ใน VSCode แล้วลง Extension
#include <stdio.h>#include <unistd.h>#include <sys/types.h>int main(){ pid_t p; p=fork(); if(p==0) //child { printf("I am child having PID %d\n",getpid()); printf("My parent PID is %d\n",getppid()); } else //parent { printf("I am parent having PID %d\n",getpid()); printf("My child PID is %d\n",p); }}OUTPUT
I am parent having PID 9445My child PID is 9446I am child having PID 9446My parent PID is 1835
#include <stdio.h>#include <unistd.h>#include <sys/types.h>int main(){ pid_t p; p=fork(); if(p==0) { sleep(5); //child goes to sleep and in the mean time parent terminates printf("I am child having PID %d\n",getpid()); printf("My parent PID is %d\n",getppid()); } else { printf("I am parent having PID %d\n",getpid()); printf("My child PID is %d\n",p); }}OUTPUT
#include <stdio.h>#include <unistd.h>#include <sys/types.h>int main(){ pid_t t; t=fork(); if(t==0) { printf("Child having id %d\n",getpid()); } else { printf("Parent having id %d\n",getpid()); sleep(15); // Parent sleeps. Run the ps command during this time }}OUTPUT
#include <unistd.h>#include <sys/types.h>#include <stdio.h>#include <sys/wait.h>int main(){ pid_t p; printf("before fork\n"); p=fork(); if(p==0)//child { printf("I am child having id %d\n",getpid()); printf("My parent's id is %d\n",getppid()); } else//parent { wait(NULL); printf("My child's id is %d\n",p); printf("I am parent having id %d\n",getpid()); } printf("Common\n");}OUTPUT
#include<stdio.h>#include<stdlib.h>#include<unistd.h>#include<sys/shm.h>#include<string.h>int main(){ int i; void *shared_memory; char buff[100]; int shmid;
/* creates shared memory segment with key 2345, having size 1024 bytes. IPC_CREAT is used to create the shared segment if it does not exist. 0666 are the permisions on the shared segment */ shmid=shmget((key_t)2345, 1024, 0666|IPC_CREAT); printf("Key of shared memory is %d\n",shmid);
//process attached to shared memory segment shared_memory=shmat(shmid,NULL,0);
//this prints the address where the segment is attached with this process printf("Process attached at %p\n",shared_memory);
printf("Enter some data to write to shared memory\n"); //get some input from user read(0,buff,100); //data written to shared memory strcpy(shared_memory,buff); printf("You wrote : %s\n",(char *)shared_memory);}OUTPUT
#include <stdio.h>#include <stdlib.h>#include <unistd.h>#include <sys/shm.h>#include <string.h>int main(){ int i; void *shared_memory; char buff[100]; int shmid; shmid=shmget((key_t)2345, 1024, 0666); printf("Key of shared memory is %d\n",shmid); shared_memory=shmat(shmid,NULL,0); //process attached to shared memory segment printf("Process attached at %p\n",shared_memory); printf("Data read from shared memory is : %s\n",(char *)shared_memory);}OUTPUT
#include<stdlib.h>#include<stdio.h>#include<string.h>#include<unistd.h>#include<sys/types.h>#include<sys/ipc.h>#include<sys/msg.h>
#define MAX_TEXT 512 //maximum length of the message that can be sent allowed
struct my_msg{ long int msg_type; char some_text[MAX_TEXT];};
int main(){ int running=1; int msgid; struct my_msg some_data; char buffer[50]; //array to store user input msgid=msgget((key_t)14534,0666|IPC_CREAT);
if (msgid == -1) // -1 means the message queue is not created { printf("Error in creating queue\n"); exit(0); }
while(running) { printf("Enter some text:\n"); fgets(buffer,50,stdin); some_data.msg_type=1; strcpy(some_data.some_text,buffer); if(msgsnd(msgid,(void *)&some_data, MAX_TEXT,0)==-1) // msgsnd returns -1 if the message is not sent { printf("Msg not sent\n"); } if(strncmp(buffer,"end",3)==0) { running=0; } }}OUTPUT
#include<stdlib.h>#include<stdio.h>#include<string.h>#include<unistd.h>#include<sys/types.h>#include<sys/ipc.h>#include<sys/msg.h>
struct my_msg{ long int msg_type; char some_text[BUFSIZ];};
int main(){ int running=1; int msgid; struct my_msg some_data; long int msg_to_rec=0; msgid=msgget((key_t)14534,0666|IPC_CREAT); while(running) { msgrcv(msgid,(void *)&some_data,BUFSIZ,msg_to_rec,0); printf("Data received: %s\n",some_data.some_text); if(strncmp(some_data.some_text,"end",3)==0) { running=0; } } msgctl(msgid,IPC_RMID,0);}OUTPUT
#include <stdio.h>#include <stdlib.h>#include <fcntl.h>#include <sys/shm.h>#include <sys/stat.h>#include <sys/mman.h>#include <unistd.h>#include <sys/types.h>
int main(){ const int SIZE = 4096; const char *name = "OS"; const char *message_0 = "Hello"; const char *message_1 = "World!"; int fd; char *ptr; fd = shm_open(name, O_CREAT|O_RDWR,0666); ftruncate(fd, SIZE); ptr = (char*)mmap(0, SIZE, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); sprintf(ptr, "%s", message_0); ptr += strlen(message_0); sprintf(ptr, "%s", message_1); ptr += strlen(message_1); getchar(); return 0;}#include <stdio.h>#include <stdlib.h>#include <string.h>#include <fcntl.h>#include <sys/shm.h>#include <sys/stat.h>#include <sys/mman.h>#include <unistd.h>#include <sys/types.h>
int main(){ const int SIZE = 4096; const char *name = "OS"; int fd; char *ptr; fd = shm_open(name, O_RDWR,0666); ptr = (char*)mmap(0, SIZE, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); printf("%s\n", (char *)ptr); shm_unlink(name); return 0;}OUTPUT
HelloWorld!