System_Software_HandsOnList2/017.c at main · superv13/System_Software_HandsOnList2 · GitHub

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/*
..........................................................................................................................................
Name : 014.c
Author : SHRUTI VERMA
Description : Write a program to execute ls -l | wc.
                a. use dup
                b. use dup2
                c. use fcntl
Date : 10 Sep 2025
..........................................................................................................................................
*/

#include<unistd.h>
#include<stdlib.h>
#include<fcntl.h>
#include<stdio.h>

void byDup() {
    int fd[2];
    pipe(fd);
        if(!fork()) {
            close(1);
            dup(fd[1]);
            close(fd[0]);
            execlp("ls", "ls", "-l", NULL);
        }
        else {
            close(0);
            dup(fd[0]);
            close(fd[1]);
            execlp("wc", "wc", NULL);
        }

}

void byDup2() {
    int fd[2];
    pipe(fd);
    if(!fork()) {
        dup2(fd[1], STDOUT_FILENO);
        close(fd[0]);
        close(fd[1]);
        execlp("ls", "ls", "-l", NULL);
    }
    else {
        dup2(fd[0], STDIN_FILENO);
        close(fd[1]);
        close(fd[0]);
        execlp("wc", "wc", NULL);
    }
}

void byFcntl() {
    int fd[2];
    pipe(fd);

    if(!fork()) {
        close(1);
        fcntl(fd[1], F_DUPFD, STDOUT_FILENO);
        close(fd[1]);
        close(fd[0]);
        execlp("ls", "ls", "-l", NULL);
    } else {
        close(0);
        fcntl(fd[0], F_DUPFD, STDIN_FILENO);
        close(fd[0]);
        close(fd[1]);
        execlp("wc", "wc", NULL);
    }

}

int main() {
    int n;
    printf("1 : dup \t 2 : dup2 \t 3 : fcntl \n enter a choice :  ");
    scanf("%d/n", &n);

    if(n==1) byDup();
    if(n==2) byDup2();
    if(n==3) byFcntl();

}

/*---------------------------------------------------OUTPUT------------------------------------------------------

       vumma@vumma-VivoBook-15-ASUS-Laptop-X507UF:~/Desktop/SS/HOL2$ gcc 017.c -o 017.out
vumma@vumma-VivoBook-15-ASUS-Laptop-X507UF:~/Desktop/SS/HOL2$ ./017.out
1 : dup          2 : dup2        3 : fcntl
 enter a choice :  2
      9      74     417
vumma@vumma-VivoBook-15-ASUS-Laptop-X507UF:~/Desktop/SS/HOL2$ gcc 017.c -o 017.out
vumma@vumma-VivoBook-15-ASUS-Laptop-X507UF:~/Desktop/SS/HOL2$ ./017.out
1 : dup          2 : dup2        3 : fcntl
 enter a choice :  1
      9      74     417
vumma@vumma-VivoBook-15-ASUS-Laptop-X507UF:~/Desktop/SS/HOL2$ gcc 017.c -o 017.out
vumma@vumma-VivoBook-15-ASUS-Laptop-X507UF:~/Desktop/SS/HOL2$ ./017.out
1 : dup          2 : dup2        3 : fcntl
 enter a choice :  3
      9      74     417
*/