midterm

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CS 476/576
Systems Programming
Fall 2008
Midterm Exam
Time 2 & 1/2 hours
Open Book & Notes

Name:

Unix Login:

Each Question is 20 points.

Question 1:

The standard UNIX command host converts a host IP address t o host domain name,

For example:

% host 128.82.4.118

118.4.82.128.in-addr.arpa domain name pointer deneb.cs.odu.edu.

Write a shell script Qhost that have the following description:

Qhost <IP address>

The output of this command is the host name.

For example:

% Qhost 128.82.4.118

deneb

Ansewer:

Question 2:

The standard UNIX command who produces a line for each login window,

For example:

% who

aamr pts/8 Oct 2 15:56 (h160202.s160.odu.edu)

cs476 pts/9 Oct 4 22:19 (antares.cs.odu.edu)

djordan pts/15 Oct 4 20:56 (c-71-63-63-218.hsd1.va.comcast.net)

cs476 pts/16 Oct 4 22:18 (antares.cs.odu.edu)

Write a shell script called Qwho that have the following description:

Qwho

The output of this command is a no-duplicate sorted list of users followed by the number of users.

For example:

% Qwho

aamr

cs476

djordan

Ansewer:

Question 3:

Write a curses program called Qcurses that displays the string name “WAHAB” diagonally as:

% Qcurses

Ansewer:

Question 4:

The following program is a listing of the xlines program presented in class.

Modify the program, call it Qxlib such that the program draws a dot at the first pointer click

After that it draws a line segment between each pointer click and the preceeding pointer click.

main(argc,argv)
int argc;
char **argv;
{

Display *display;
Window root, window;
long fgcolor, bgcolor;
int screen, pointx, pointy ;
int FirstPt = TRUE;
long eventmask = ButtonPressMask|ExposureMask|KeyPressMask;
XEvent event;
XGCValues gcval;
GC draw;
Colormap cmap;
XColor color, ignore;
char *colorname = "blue";

if (!(display = XOpenDisplay(argv[1]))) {
perror("XOpenDisplay");
exit(1);
}

root = RootWindow(display,screen = DefaultScreen(display));
fgcolor = BlackPixel(display,screen);
bgcolor = WhitePixel(display,screen);

window = XCreateSimpleWindow(display,root,0,0,400,400,2,fgcolor,bgcolor);

cmap = DefaultColormap (display, screen);
XAllocNamedColor(display, cmap, colorname, &color, &ignore);
fgcolor = color.pixel;
gcval.foreground = fgcolor;
gcval.background = bgcolor;
draw = XCreateGC(display,window,GCForeground|GCBackground,&gcval);

XSelectInput(display,window,eventmask);
XMapWindow(display,window);

for (;;) {

XWindowEvent(display,window,eventmask,&event);

switch (event.type) {

    case Expose:
      XClearWindow(display,window);
      break;

    case ButtonPress:
      if (FirstPt) {
        FirstPt=FALSE;
        pointx = event.xbutton.x;
        pointy = event.xbutton.y;
        XDrawPoint (display,window,draw, pointx, pointy);
        break;
      }
      else {
        FirstPt=TRUE;
        XDrawLine (display,window,draw, pointx,pointy,
            event.xbutton.x, event.xbutton.y);
        break;
      }

    case KeyPress:
      exit(0);
    default:
      fprintf(stderr,"Unexpected event: %d\n",event.type);
    }
}
}

Question 5:

The following program creates a motif interface with a ingle button, the Quit button.

Modify the program, call it Qmotif, to add two more buttons labeled Qcurses and Qxlib

to execute the commands of Questions 3 and 4.

void quitCallback ( Widget w, XtPointer clientData, XtPointer callData );

void main ( int argc, char **argv )
{
Widget shell, commands, quit;

      XtAppContext app;

            shell = XtAppInitialize ( &app, "Xecute", NULL, 0, &argc, argv, NULL, NULL, 0 );

      commands = XtVaCreateManagedWidget ( "commands", xmRowColumnWidgetClass, shell, XmNnumColumns, 3, XmNorientation, XmHORIZONTAL, NULL );

     quit = XtVaCreateManagedWidget ( "Quit", xmPushButtonWidgetClass, commands, NULL, 0 );

XtAddCallback ( quit, XmNactivateCallback, quitCallback, NULL);

      XtRealizeWidget ( shell );
            XtAppMainLoop ( app );
}

void quitCallback ( Widget w, XtPointer clientData, XtPointer callData )
{
            exit ( 0 );
}