I/O System Calls > C Program

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I/O System Calls > C Programs

Program 1

#include<stdio.h>
#include<stdlib.h>
#include<sys/types.h>
#include<sys/stat.h>
#include<unistd.h>
#include<errno.h>
int main(int argc,char*argv[])
{
pid_t pid;
pid=fork();

printf("1st fork\n");
printf("Process Id:%d,Parent ProcessId:%d\n",getpid(),getppid());
printf("2nd fork\n");
printf("Process Id:%d,Parent ProcessId:%d\n",getpid(),getppid());
printf("3rd fork\n");
printf("Process Id:%d,Parent ProcessId:%d\n",getpid(),getppid());
return 0;
}
/*
OUTPUT----------
[root@Server Desktop]# gcc systemcall.c
[root@Server Desktop]# ./a.out
1st fork
Process Id:3622,Parent ProcessId:3621
2nd fork
Process Id:3622,Parent ProcessId:3621
3rd fork
Process Id:3622,Parent ProcessId:3621
1st fork
Process Id:3621,Parent ProcessId:3567
2nd fork
Process Id:3621,Parent ProcessId:3567
3rd fork
Process Id:3621,Parent ProcessId:3567
[root@Server Desktop]# ./a.out
1st fork
Process Id:3624,Parent ProcessId:3623
2nd fork
Process Id:3624,Parent ProcessId:3623
3rd fork
Process Id:3624,Parent ProcessId:3623
1st fork
Process Id:3623,Parent ProcessId:3567
2nd fork
Process Id:3623,Parent ProcessId:3567
3rd fork
Process Id:3623,Parent ProcessId:3567

*/

Program 2

#include<sys/stat.h>

#include<fcntl.h>

#include<sys/types.h>

#include<stdio.h>

int main()

{

int n, i=0;

int f1, f2;

clrscr();

char c, strin[100];

f1=open("data",O_RDWR|O_CREAT|O_TRUNC);

c=getchar();

while(c!='\n') {

strin[i++]=c;

}

strin[i]='\0';

write(f1, strin, i);

close(f1);

f2=open("data",O_RDONLY);

read(f2, strin, 0);

printf("\n%s\n",strin[i]);

close(f2);

return 0;

}

Output:

Hello

Hello