Question

I’m looking for a solution to writing a piece of program in C++ on Linux that parses a file which contains programs with a set arguments, then runs those programs with their arguments arguments.

Each program (line) is executed one at a time and then the parent process waits for each child to exit and inspects it’s exit status (i’m only interested if it is 0).

Example of text to be parsed:

prog1 -a arg1 -m arg2 -c arg3
prog2 arg1 arg2 arg3 arg4
….

I believe it is best to store everything in a vector of strings, eg:

vector <std::string> p_vector;
while (getline(file, line))
    p_vector.push_back(line);

then, for each element i from 0 to p_vector.size() I need to do something like the example I found on the net:

if(fork() = 0) //? shouldn't here be == ?
{
    execv(fullpath,argv);//does full path mean my p_vector[i]? or the child process and then argv is a list of space delimited arguments?
    exit(1);
}
else
{
    int *status;
    wait(status);
    if(*status == 0)
    printf("%s exited correctly", fullpath);//fullpath, right?
    else
    //other printf error
}

or, should I better use for this

string command = p_vector[i]; // eg: ls -l -a -l folder_one , put more arguments because I do not know the exact number of them for each parsed line

int exitCode = system(command.c_str());

If anyone has also an idea of how to do this using a script, that would be welcome too, although the scope of my question is C++!

I could have used Qt’s QProcess as I know how to use that one but that might raise some legal issues of which I’m now aware right now (there’s no problem with sharing the code however, the company I work for may not allow that)

Thanks and looking forward to getting some answers from you!

Answer 1

I agree with Ignacio. But if you have to do it , then I would prefer you using System/popen command.

BUT MAKE SURE YOU ARE NOT RUNNING ANY COMMAND THAT WOULD LAND YOU TO TROUBLE.. like ” rm -rf * “.

This is very likely to happen if you are going to read from a file which cannot be trusted with.

And no need to copy it to new string you can do “system(p_vector[i].c_str());”