Unix commands in C code

Question

I need to implement ps -auxj, grep "user id", and wc. I already have word count, but I'm not sure how to do the others while they have parameters. This is what I have so far.

int main() {
int pfd[2];
int pid;

if (pipe(pfd) == -1) {
    perror("pipe failed");
    exit(-1);
}
if ((pid = fork()) < 0) {
    perror("fork failed");
    exit(-2);
}
if (pid == 0) {
    close(pfd[1]);
    dup2(pfd[0], 0);
    close(pfd[0]);
    execlp("wc", "wc", (char *) 0);
    perror("wc failed");
    exit(-3);
} 
else {
    close(pfd[0]);
    dup2(pfd[1], 1);
    close(pfd[1]);
    execlp("ls", "ls", (char *) 0);
    perror("ls failed");
    exit(-4);
}
exit(0);

}

Any help in the right direction would be great.

Have you looked at man 3 exec yet? It should explain everything you need to know about argument passing using the exec* functions. — user142162
– user142162, Commented Oct 29, 2013 at 23:41

sraok · Accepted Answer · 2013-10-29 23:44:12Z

3

exec gives details about how to pass arguments to the exec family of functions. e.g.

execl("ls", "ls", "-l",(char *) 0);

you can choose from there whatever suits you.

answered Oct 29, 2013 at 23:44

sraok

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