In below program I want to add (as part of the valid_cmds string) the pwd (print working directory), lo (logout), and cd (change directory) commands. However when I add those into original program ;
char *valid_cmds = " ls ps df pwd lo cd";
they are not working I have the cout message huh?
Original source code is below
Code:
#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <unistd.h>
using namespace std;
const int MAX =256;
const int CMD_MAX=10;
char *valid_cmds = " ls ps df ";
int
main( ){
char line_input[MAX], the_cmd[CMD_MAX];
char *new_args[CMD_MAX], *cp;
int i;
while (1) {
cout << "cmd> ";
if (cin.getline(line_input, MAX, '\n') != NULL) {
cp = line_input;
i = 0;
if ((new_args[i] = strtok(cp, " ")) != NULL) {
strcpy(the_cmd, new_args[i]);
strcat(the_cmd, " ");
if ((strstr(valid_cmds, the_cmd) - valid_cmds) % 4 == 1) {
do {
cp = NULL;
new_args[++i] = strtok(cp, " ");
} while (i < CMD_MAX && new_args[i] != NULL);
new_args[i] = NULL;
switch (fork( )) {
case 0:
execvp(new_args[0], new_args);
perror("exec failure");
exit(1);
case -1:
perror("fork failure");
exit(2);
default:
// In the parent we should be waiting for
// the child to finish
;
}
} else
cout << "huh?" << endl;
}
}
}
}
