CODEWITHSUNDEEP
cfilehttp-redirectexecv
user1162954
user1162954

Reputation: 267

redirecting output of execvp into a file in C

I don't know what I am doing wrong... but here is the snippet of code that is being executed:

if (fork() == 0)
    {       
             // child
        int fd = open(fileName, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR);

        dup2(fd, 1);   // make stdout go to file

        execvp("ls","ls");
        close(fd);
            exit(0);
    }
if(wait(&status) == -1)
    {
        printf("ERROR REDIRECT\n");
    }

fileName gets created but there is nothing inside.What am I doing wrong?

Upvotes: 3

Views: 12764

Answers (2)

Sandeep Raju
Sandeep Raju

Reputation: 11

close fd before execvp. because the code after execvp never runs unless execvp fails.

Upvotes: 1

cnicutar
cnicutar

Reputation: 182649

My guess is that the execvp doesn't work but since you don't handler errors you don't see it.

Try this:

char *const args[] = {"ls", NULL};
execvp(args[0], args);

/* If this is reached execvp failed. */

perror("execvp");

Alternatively you can use compound literals:

execvp("ls", (char *[]){"ls", NULL});

Second idea: try to run things normally, without redirect and see how it works.

Upvotes: 6

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