Perhaps someone might find it usefull...

[Kimm]

I wrote this program to run a game of mine, I cant realy write bash scripts but I know C++ pretty well so I fugured I can write something in C++ that does this instead.

I usualy write more advanced programs but this is just a handy little thing I made.
Its a program that launches a program along with all the arguments that you give it, Its realy a very silly program but I supose someone else might have use for it, if not else I supose you can just examine the code and perhaps learn something from it (if your a beginner). If you want it to run a different executable you have to change the code though

This runns Jedi Knight: Jedi Academy through cedega (see arg variable)


#include <stdlib.h>
#include <string.h>

int main(int argc, char *argv[])
{
char arg[200] = "cd /home/kimm/Program/JKA\ncedega jamp.exe ";
int argi = argc - 1, temp;

if(argi != 0)
{
for(temp = 0;temp <= argi; temp++)
{
strcat(arg, argv[temp]);
strcat(arg, " ");
}
}

system(arg);

return 0;
}

[LordHunter317]

There are much better ways of doing this, generally. Look into the exec() family of calls.

[Kimm]

I supose, I do know most of the acctual C++... but when it comes to what Library to use and what all the functions do, I usualy stand clueless.

I tried looking for exec() on C++ without any luck, perhaps you can provide me with a link?

[LordHunter317]

I tried looking for exec() on C++ without any luck, perhaps you can provide me with a link?Run 'apropos exec' on your system and you should get a series of POSIX standard calls with names like 'execle' and 'execvp'.

[jerome bettis]

yeah you should use fork and execvp and wait for the child process to return.

[jerome bettis]

i had to do this sort of thing about 6 months ago. i found the file and wasn't satisfied with the way i was doing things back then so i reworked it a little bit. any criticism or suggestions to improve code quality and even new features is welcome.

// shell.cpp
// a _very_ simple unix shell.
// supports arguments but not > < | & or anything fancy like that yet
//
// 1. read command from user
// 2. tokenize command and arguments
// 3. fork off a process
// 4. exec the command
// 5. wait for it to return
// 6. repeat until exit

#include <iostream>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <string>
#include <sstream>
#define SIZE 100
using namespace std;

// reads a command from cin and tokenizes it for the args.
// places these tokens in supplied array
// returns the number of tokens
int getCmd(char** cmd) {
const char* prompt = "$ ";
cout << prompt;
string buff;
getline(cin, buff);
istringstream is(buff);
int j = 0;
is >> buff; // get token
while (is) { // while stream is good
cmd[j] = new char;
strncpy(cmd[j++], buff.c_str(), SIZE); // copy to array
is >> buff;
}
return j;
}

inline void forkFailed() {
cerr << "fork failed.\n";
exit(1);
}

inline void excevpFailed(const char* str) {
cerr << str << ": command not found.\n";
exit(1);
}

int main(int argc, char** argv) {
char** cmd = new char*[SIZE];
pid_t childId, waitId;
int childStat;
int cmdSize = getCmd(cmd); // read a command
while (strncmp(cmd[0], "exit", SIZE)) { // go until exit
childStat = 0;
if ((childId = fork()) == -1) { // fork off another process
forkFailed();
} else if (childId == 0) { // execute command
execvp(cmd[0], cmd); // if the child gets to
excevpFailed(cmd[0]); // this line, something's wrong
} else if (childId == (pid_t)(-1)) {
forkFailed();
} else { // wait for child to return
waitId = wait(&childStat);
}
for (int i = 0; i < cmdSize; i++) {
cmd[i] = NULL;
}
cmdSize = getCmd(cmd);
}
return 0;
}