wait.c

在UNIX/LINUX下面挂起一个进程并在SHELL下观察进程.

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/wait.h>

/* Spawn a child process running a new program. PROGRAM is the name 
   of the program to run; the path will be searched for this program. 
   ARG_LIST is a NULL-terminated list of character strings to be 
   passed as the program's argument list. Returns  the process ID of 
   the spawned process.  */ 
 
int spawn (char* program, char** arg_list) 
{
  pid_t child_pid; 
 
  /* Duplicate this process. */ 
  child_pid = fork (); 
  if (child_pid != 0) 
    /* This is the parent process. */ 
    return child_pid; 
  else {
    /* Now execute PROGRAM, searching for it in the path.  */ 
    execvp (program,  arg_list); 
    /* The execvp  function returns only if an error occurs.  */ 
    fprintf (stderr,  "pid: %d, an error occurred in execvp\n", (int)getpid()); 
    abort (); 
  } 
} 

int main  () 
{
  int child_status; 
 
  /* The argument list to pass to the "ls" command.  */ 
  char* arg_list[] = {
    "ls",     /* argv[0], the name of the program.  */ 
    "-l", 
    "/", 
    NULL /*  The  argument list must end with a NULL.  */ 
  }; 
 
  /* Spawn a child process running the "ls" command. Ignore the 
     returned child process ID.  */ 
  spawn ("ls", arg_list); 
 
  /* Wait for the child process to complete.  */ 
  wait (&child_status); 
  if (WIFEXITED (child_status)) 
    printf ("the child process exited normally, with exit code %d\n", 
            WEXITSTATUS (child_status)); 
  else 
    printf ("the child process exited abnormally\n"); 
 
  return  0; 
}