cmd_runner.cc

#include <string>
// #include <vector>
#include <unistd.h>

void execute(const char*, const char*);

int main(int argc, char *argv[]) {
    if (argv[1] == NULL || argv[2] == NULL) {
      printf("Usage %s PATH 'cmd0 ; cmd1 ; ...\n", argv[0]);
      exit(2);
    }

    const std::string delim = ";", s = argv[2];

    unsigned start = 0U;
    size_t end = s.find(delim);
    // std::vector<std::string> tokens;
    if (end == std::string::npos) {
        execute(argv[1], s.c_str());
        // tokens.push_back(s);
    }
    else while (end != std::string::npos) { 
        execute(argv[1], s.substr(start, end - start).c_str());
        // tokens.push_back(s.substr(start, end - start));
        start = end + delim.length();
        end = s.find(delim, start);
    }

    printf("%s\n", s.substr(start, end).c_str());
}

void execute(const char* path, const char* command) {
    printf("execute(%s) with PATH: %s\n", command, path);

    const pid_t i = fork();
    printf("i = %d\n", i);
    if (i > -1) {
        char* p = strdup(path);
        const int ret = execl(strcat(p, strcat("/", command)), "-1", (char *)0);
        free(p);
        _exit(ret);
    } else {
        perror("fork failed");
        _exit(3);
    }
}

output.txt

$ g++ -std=c++11 -Wno-writable-strings cmd_runner.cc -o cmd_runner && ./cmd_runner /bin ls
execute(ls) with PATH: /bin
i = 11202
i = 0
Bus error: 10