Fill in the blanks. include include #include include int main (void) pid.t child

Question

Fill in the blanks.

include include #include include int main (void) pid.t childpid; int fd [2]; ) setup a pipe */ perror (" Failed to setup pipeline"); return 1: * fork a child * perror (" Failed to fork a child"); return 1; )/*env is the child / perror (" Failed to redirect stdout of env"); perror (" Failed to close extra pipe descriptors on env"); execl perror("Failed to exec env”); else if ( ) /*close unused file descriptor */ else execute env return 1; grep is the parent else f else perror(" Failed to redirect stdin of grep"); perror(" Failed to close extra pipe file descriptors on grep"); execl ) *execute "grep HOME" perror(" Failed to exec grep"); return 1: Asg red o.c

Explanation / Answer

#include <errno.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
int main(void){
pid_t childpid;
int fd[2];
if(pipe(fd) == -1){ /*setup a pipe*/
perror("Failed to setup pipeline");
return 1;
}
if((childpid = fork()) == -1){ /*fork a child*/
perror("Failed to fork a child");
return 1;
}
if(childpid == 0){ /*env is the child*/
if(dup2(fd[1],STDOUT_FILENO)==-1)
perror("Failed to redirect stdout of env");
else if(close(fd[0] == -1)) /*close unused file descriptor*/
perror("Failed to close extra pipe descriptors on env");
else{
execl("/usr/bin/env", "env", NULL); /*execute env*/
perror("Failed to exec env");
}
return 1;
}
if(dup2(fd[0],STDIN_FILENO)==-1) /*grep is the parent*/
perror("Failed to redirect stdin of grep");
//else if(close(fd[1]==-1))
//perror("Failed to close extra pipe file descriptors on grep");
else{
execl("/bin/grep", "grep", "HOME", NULL); /*execute "grep HOME"*/
perror("Failed to exec grep");
}
return 1;
}

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