Exit () _ exit () terminate the process

/*

* _ Exit () stop the process immediately and clear the space used and various data structures in the kernel.

* Before exit (), call the exit handler to clear the I/0 buffer.

*/

# Include <stdio. h> // file preprocessing, including the standard input/output Library

# Include <unistd. h> // file preprocessing, including the fork function library
# Include <sys/types. h> // file preprocessing, including the fork function library
# Include <stdlib. h> // file preprocessing, including the exit function library
Void terminal_progress ()
{
Pid_t result; // The PID used to store the fork returned sub-process
Result = fork (); // call the fork function. The returned values are stored in the result variable.
If (result =-1) // you can use the result value to determine the return status of the fork function,
{
Perror ("failed to create sub-process! \ N ");
Exit (0 );
}
Else if (result = 0) // The value 0 indicates the sub-process.
{
Printf ("test termination process _ exit ()! \ N ");
Printf ("We use cache for this line! ");
_ Exit (0 );
}
Else // If the returned value is greater than 0, the parent process is returned.
{Sleep (10 );
Printf ("test termination process exit ()! \ N ");
Printf ("We use cache for this line! ");
Exit (0 );
}

}

/*
* This program shows how to avoid zombie processes.
*/
# Include <stdio. h> // file preprocessing, including the standard input/output Library
# Include <unistd. h> // file preprocessing, including the fork function library
# Include <sys/types. h> // file preprocessing, including fork, wait, and waitpid function libraries
# Include <sys/Wait. H> // file preprocessing, including the wait and waitpid function libraries
Void zombie_progress ()
{
Pid_t PID, wpid;
Int status, I;
PID = fork (); // call the fork function to copy the process
If (pid = 0) // If the returned value is 0, it indicates the sub-process.
{
Printf ("this is a sub-process, process number (PID) is: % d \ n", getpid ());
Sleep (5); // The sub-process waits for 5 seconds.
Exit (6 );
}
Else
{
Printf ("this is the parent process, waiting for the child process... \ n ");
Wpid = wait (& status); // The parent process calls the wait function to eliminate zombie processes.
I = wexitstatus (Status); // obtain the status when the sub-process exits through the integer pointer status
Printf ("the process Number of the waiting process is: % d, end status: % d \ n", wpid, I );
}
}

# Include <stdio. h> // file preprocessing, including standard input/output functions
# Include <unistd. h> // file preprocessing, including the fork function library
# Include <sys/types. h> // file preprocessing, including fork, wait, and waitpid function libraries
# Include <sys/Wait. H> // file preprocessing, including the wait and waitppid function libraries
Void display0 ();
Void display1 ();
Void display2 ();
Void Cisco ()
{
Pid_t result;
Int status, select, num;
Void (* Fun [3]) (); // use the function pointer to create three subprograms
Fun [0] = display0;
Fun [1] = display1;
Fun [2] = display2;
Printf ("1. Copy process \ n 2, do not copy process \ n please input your choice :");
Scanf ("% d", & select );
If (select = 1) // if the user inputs 1, the replication process
{
Result = fork (); // call the fork function to copy the process. The returned value exists in the // variable result
If (result =-1)
{
Perror ("replication process error ");
Exit (1 );
}
If (result = 0) // sub-process
{
Printf ("this is a sub-process (process number: % d, parent process number: % d):", getpid (), getppid ());
Printf ("go to the Cisco (Cisco) 1912 switch boot interface. \ n ");
Printf ("1 user (s) now active on Management Console. \ n ");
Printf ("\ t uer interface menu \ n ");
Printf ("\ t [0] Menu \ n ");
Printf ("\ t [1] command line \ n ");
Printf ("\ t [2] IP configuration \ n ");
Printf ("Enter Selection :");
Scanf ("% d", & num);/* use the function pointer to run the corresponding program */
If (Num> = 0 & num <= 2)
(* Fun [num]) ();
Exit (0 );
}
Else
{
Waitpid (result, & status, wnohang);/* wnohang does not block the parent process */
/* The parent process calls the waitppid function to remove zombie processes */
Printf ("this is the parent process (process number: % d, parent process number: % d) \ n", getpid (), getppid ());
If (wifexited (Status) = 0)
Printf ("sub-process terminated abnormally, sub-process terminated status: % d \ n", wifexited (Status ));
Else
Printf ("sub-process terminated normally, sub-process terminated status: % d \ n", wifexited (Status ));
Exit (0 );
}
}
}
Void display0 ()
{
Printf ("you have selected to enter the menu mode \ n ");
}
Void display1 ()
{
Printf ("you have chosen to enter the command line mode \ n ");
}
Void display2 ()
{
Printf ("you choose to enter IP Address Configuration Mode \ n ");
}