Unix/linux Process details-code

Unix/linux Process details-code

#include <iostream>#include <vector>#include <cstdint>#include <cstring>#include <error.h>#include <unistd.h>using namespace std;int main(){    //system("ps aux &");//run on background    char *const ps_argv[]={"ps", "ax", 0};    //eg env    char *const ps_envp[]={"PATH=/bin:/usr/bin","TERM=console",0};    //possible exec    //execl("/bin/ps","ps","ax",0);//assume ps in the bin    //execlp("ps","ps","ax",0);//assume /bin is in the PATH    execle("/bin/ps","ps","ax",0,ps_envp);//pass own env    //execv("/bin/ps",ps_argv);//    execvp("ps",ps_argv);//    execve("/bin/ps",ps_argv,ps_envp);//    execlp("ps","ps","ax",0);   pid_t new_pid;    new_pid = fork();    new_pid = getpid();    cout << new_pid << endl;    switch (new_pid) {    case -1:        break;    case 0:        break;    default:        break;    }    cout << "errx" << endl;    return 0;}

 

#include <iostream>#include <vector>#include <cstdint>#include <cstring>#include <error.h>#include <unistd.h>#include <sys/types.h>using namespace std;int main(){    pid_t pid;    string message;    int n;    pid = fork();    //pid = getpid();    //cout << pid << endl;    switch (pid) {    case -1:        perror("fork failed");        exit(1);    case 0:        message = "this is the child";        n=5;        break;    default:        message = "this is the parent";        n=3;        break;    }    for(; n > 0;n--)    {        cout<<message<<endl;        sleep(1);    }    //cout << "errx" << endl;    return 0;}this is the parentthis is the childthis is the parentthis is the childthis is the parentthis is the child$ this is the childthis is the child#include <iostream>#include <vector>#include <cstdint>#include <cstring>#include <error.h>#include <unistd.h>#include <sys/types.h>#include <sys/wait.h>using namespace std;int main(){    pid_t pid;    string message;    int n;    int exit_code;    pid = fork();    //pid = getpid();    //cout << pid << endl;    switch (pid) {    case -1:        perror("fork failed");        exit(1);    case 0:        message = "this is the child";        n=5;        exit_code = 37;//casual set        break;    default:        message = "this is the parent";        exit_code = 0;        n=3;        break;    }    for(; n > 0;n--)    {        cout << message << ",which pid:" << getpid() << endl;        sleep(1);    }    if(pid != 0)    {        int stat_val;        pid_t child_pid;        child_pid = wait(&stat_val);        printf("child has finished: PID = %d\n",child_pid);        if(WIFEXITED(stat_val))            printf("child exited with code %d\n",WEXITSTATUS(stat_val));        else {            printf("child terminated abnormally\n");        }    }    //cout << "errx" << endl;    exit(exit_code);}