STATUS OF SYSTEM FUNCTION --APUE

#include "apue.h"

int main(int argc ,char * argv[])
{
    int status;

    if (argc < 2)
        err_quit("command required ");

    if ((status  = system(argv[1])) < 0)
        err_sys("system() error");
    pr_exit(status);
    exit(0);
}

#include "apue.h"
#include <sys/wait.h>

void pr_exit(int status)
{
    if (WIFEXITED(status))
        printf("normal termination ,exit status = %d \n",WEXITSTATUS(status));
    else if (WIFSIGNALED(status))
        printf("abnormal termination signal nuber =%d %s\n",WTERMSIG(status),
        #ifdef WCOREDUMP
                WCOREDUMP(status) ? "(core file generated",:" null");
            #else
            "null");
        #endif
    else if (WIFSTOPPED(status))
        printf("child stopped,signal number = %d\n",WSTOPSIG(status));
    printf("just for test the exit \n");
}

Script started on Fri 17 Feb 2012 09:10:43 PM CST
ubuntu@ubuntu-virtual-machine:~/Desktop/apue/ch8$ ls -lai tsys

791487 -rwxrwxr-x 1 ubuntu ubuntu 7913 2012-01-05 18:45 [
ubuntu@ubuntu-virtual-machine:~/Desktop/apue/ch8$ ^C

ubuntu@ubuntu-virtual-machine:~/Desktop/apue/ch8$ tsys "sleep 60"
^Cabnormal termination signal nuber =2 null

just for test the exit

ubuntu@ubuntu-virtual-machine:~/Desktop/apue/ch8$ ./tsys "sleep 60"

^\abnormal termination signal nuber =3 null

just for test the exit

ubuntu@ubuntu-virtual-machine:~/Desktop/apue/ch8$ sh

$ sh -c "sleeop 60"

^C

$ echo $?

130

$ sh -c "sleeopp 60"

^\Quit

$ echo $?

131

$ exit

ubuntu@ubuntu-virtual-machine:~/Desktop/apue/ch8$ ./tsys "sleep 60" &

[1] 3124

ubuntu@ubuntu-virtual-machine:~/Desktop/apue/ch8$ ps -f

UID        PID  PPID  C STIME TTY          TIME CMD

ubuntu    3058  3057  0 21:10 pts/0    00:00:00 bash -i

ubuntu    3124  3058  0 21:12 pts/0    00:00:00 ./tsys sleep 60

ubuntu    3125  3124  0 21:12 pts/0    00:00:00 sh -c sleep 60

ubuntu    3126  3125  0 21:12 pts/0    00:00:00 sleep 60

ubuntu    3127  3058  0 21:12 pts/0    00:00:00 ps -f

ubuntu@ubuntu-virtual-machine:~/Desktop/apue/ch8$ kill -KILL 3125

abnormal termination signal nuber =9 null

just for test the exit

[1]+  Done                    ./tsys "sleep 60"

ubuntu@ubuntu-virtual-machine:~/Desktop/apue/ch8$ exit

exit


Script done on Fri 17 Feb 2012 09:13:05 PM CST

需要注意的是，直接调用的返回值和shell的终止状态时不一样的，在着，直接运行该程序，然后kill的返回值和书上说的不一样，这里直接返回了信号值，杀死调用shell的返回值和直接调用system的值也是
不一样的