确定是否安装了C ++命令行程序

Question

I am trying to find out if a command line program is installed, so that it can be used later.

So far what I have tried is:

int whichReturn = system("command -v THE_CL_PROGRAM >/dev/null && { exit 50; }|| { exit 60; }");
if (whichReturn == 12800) { //system 'apparently' returns the return value *256 (50*256 = 12800)

    //...

}

However it seems that it always returns 60 and so fails.

Is there an easier way to do this? Or can someone point out where my mistake is please?

Thanks

Answer 1

A complete program using which :

isthere.cpp:

#include <iostream>
#include <cstdlib>
#include <sstream>

int main(int argc, char* argv[])
{
        std::ostringstream cmd;
        cmd << "which " << argv[1] << " >/dev/null 2>&1";
        bool isInstalled = (system(cmd.str().c_str()) == 0);
        std::cout << argv[1] << " is "<< ((isInstalled)?"":"NOT ") << "installed! << std::endl;
}

Output:

$ ./isthere ls
ls is installed!
$ ./isthere grep
grep is installed!
$ ./isthere foo
foo is NOT installed!