create process on Linux & Windows

// Create child process && exec current program [ set lock ]
// Windows
#include
#include
#include
#include
#define MAX_LINE_LEN 80

bool checkRunning()
{
    int res = access("d:\lock.dat", 0);
    if (res == 0) {
        printf("exit....\n");
        return true;
    }
    FILE* fid;
    fid = fopen("d:\lock.dat", "w+");
    char a[] = "ddd";
    fwrite(a, strlen(a), 1, fid);
    fclose(fid);
    return false;
}

int main(int argc, char* argv[])
{
    //local variables
    FILE* fid;
    char cmdLine[MAX_LINE_LEN];
    //CreateProcess parameters
    LPSECURITY_ATTRIBUTES processA=NULL;//Default
    LPSECURITY_ATTRIBUTES threadA=NULL;//Default
    BOOL shareRights=TRUE;//Default
    DWORD creationMask=CREATE_NEW_CONSOLE;//Window per process.
    LPVOID enviroment=NULL;//Default
    LPSTR curDir=NULL;//Default
    STARTUPINFO startInfo;//Result
    PROCESS_INFORMATION procInfo;//Result


    if (checkRunning()) {
        Sleep(1000 * 20 );
    }


    //1.Read the command line parameters

    if(argc!=2)
    {
        fprintf(stderr,"Usage:lanch\n");
        exit(0);
    }

    //2.Open a file that coutain a set of commands


    fid=fopen(argv[1],"r");
    if (fid == NULL) {
        printf("function fopen() failed!!!\n");
        return 1;
    }
    //3.For every command in the launch file

while(fgets(cmdLine,MAX_LINE_LEN -1 ,fid)!=NULL)
{
    //Read a command from the file
    if(cmdLine[strlen(cmdLine)-1]=='\n')
    cmdLine[strlen(cmdLine)-1]='\0';//Remove NEWLINE
    //Create a new process to execute the command
    ZeroMemory(&startInfo,sizeof(startInfo));
    startInfo.cb=sizeof(startInfo);
    printf("%s\n", cmdLine);
    if(!CreateProcess(
        NULL,//File name of executable
            cmdLine,//command line
            processA,//Process inherited security
        threadA, //Thread inherited security
        shareRights,//Rights propagation
        creationMask,//various creation flags
        enviroment,//Enviroment variable
        curDir, //Child's current directory
        &startInfo,
        &procInfo
        )
    )
    {
    fprintf(stderr,"CreatProcess failed on error %d\n",GetLastError());
    ExitProcess(0);
    }
}


    Sleep(1000 * 40 );

//Terminate after all commands have finished.
return 0;
}






// fork() child process && exec other program
// Linux .

#include
#include
#include
using namespace std;

int main()
{
    cout << "test process begin..." << endl;
    string  child_process = "./out_child";
    
    cout << "begin to create child process: " << child_process << endl;
   
    pid_t pd = fork();

    if (pd == 0 ) {
        cout << "########### child ################" << endl;
        int res = execl(child_process.c_str(), (char*)NULL);
        if (res < 0 ) {
            cout << "function execl() failed!!!" << endl;
        }
        cout << "########### child ################" << endl;
       
    }
    else if (pd > 0) {
        sleep(30);
    }
    else {
        cout << "function fork() failed!!!" << endl;
    }
   
    cout << "test process end..." << endl;
    return 0;
}