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CS 476/576
Systems Programming
Fall 2010
Midterm Exam

Time 2 & 1/2 hours
Open Book & Notes

 

 

 

Login:

 

Name:

Question 1:  45 points (each part 15 points)

 

A:

The  UNIX command  last  displays a line for each successful login at the local  host.

The format for one line of user wahab is:

wahab     sshd         dhcp-154.cs.odu. Sat Aug 28 17:42 - 17:59  (00:16)

 

Write a shell script called lastcount   that produces the number of unique users who successfully logged to the local host.

For example:

% lastcount

942

 

Solution Q1A (lastcount)

 

 

B:

The  UNIX command hostname   display the host name where the user is logged in.

For example:

% hostname

vega

 

The UNIX command  who am i   display one  line of  user information.

For example:

% who am I

cs476    pts/15       2010-10-14 19:17 (dhcp-154.cs.odu.edu)

 

Write a shell script  called  whoami  that display the  host name and user information in the following format:

 % whoami

HOST: vega

LOGIN: cs476

SINCE: 2010-10-14 19:17

FROM: dhcp-154.cs.odu.edu

 

Solution Q1B (whoami)

 

 

C:

Write a shell script called listmygroup to list all members of the same group as the user executing the script.

The list should be  sorted by login names.

For Example for user wahab, the group is 13, and the program lists all users whose group is 13.

% listmygroup

....

maly:Kurt Maly

mln:Michael Nelson

mukka:Ravi Mukkamala

mweigle:Michele Weigle

olariu:Stephan Olariu

wahab:Hussein Abdel-Wahab

....

 

Note that:

 % ypcat passwd

the line for user wahab is:

wahab:stg/i.0xxJ1zU:51:13:Hussein Abdel-Wahab:/home/wahab:/usr/local/bin/tcsh

 

Solution Q1C (listmygroup)

 

 

 

Question 2: 15 points

 

Write a curses program called  Q2   that randomly selects a row  R and a colum C. Then displays the string X (R, C)

at curses  position (R, C). Assume we have 20 rows and 80 columns.

 

Examples:

 

% Q2 

 

 

 

                                         X (4, 20)

 

% Q2

                                                                                X (2, 40)

Solution Q2 (curses)

Question 3: 20 points

 

 

Modify the following xlib program to draw a line between the click point and the nearest corner of the drawing area.

For example if the click pint is  (x,y) where x < 300 and y < 300, then the  nearest corner is (0,0).

 

 

Q3.c:

 

main(argc,argv)

int argc;

char **argv;

{

    Display *display;

    Window root, window;

    long fgcolor, bgcolor;

    int screen, pointx, pointy ;

    long eventmask = ButtonPressMask|ExposureMask|KeyPressMask;

    XEvent event;

    XGCValues gcval;

    GC draw;

    Colormap cmap;

    XColor color, ignore;

    char *colorname = "Red";

 

    display = XOpenDisplay(argv[1]);

    root = RootWindow(display,screen = DefaultScreen(display));

    fgcolor = BlackPixel(display,screen);

    bgcolor = WhitePixel(display,screen);

    window = XCreateSimpleWindow(display,root,0,0,800,800,2,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:

            pointx = event.xbutton.x;

            pointy = event.xbutton.y;

            XDrawPoint (display,window,draw, pointx, pointy);

 

 

 

 

 

 

 

 

 

 

 

 

 

         break;

          case KeyPress:

            exit(0);

      

     }

    }

}

 

 

Solution Q3.c:

 

Question 4: 20 points

 

The program Q4  accepts one argument and creates a motif interface with two buttons.

 

For Example:

 

% Q4   “ls –lt”

 

Will create two buttons: QUIT and ls –lt

Clicking on QUIT terminates the program.

Clicking on ls –lt executes the UNIX command:  ls –lt.

 

Modify the program so that it accepts any number of arguments and creates as many buttons.

 

For example:

 

       %Q4   “who am I”   “last”   “ls -l”   “date”   “host fast”

 

Creates the following interface:

 

 

 

Clicking on the QUIT button terminates the program.

Clicking on any other button executes the corresponding UNIX command.

 

Q4.c:

 

 

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

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

 

void main ( int argc, char **argv )

{

     Widget shell, commands, quit, cmd;

     XtAppContext app;

 

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

    

      quit = XtVaCreateManagedWidget ( "QUIT", xmPushButtonWidgetClass, commands, NULL );

     XtAddCallback ( quit, XmNactivateCallback, quitCallback, NULL );

       

      commands = XtVaCreateManagedWidget ( "commands", xmRowColumnWidgetClass, shell, XmNnumColumns, 3,

                            XmNorientation, XmHORIZONTAL, NULL );

 

 

 

 

 

 

 

     cmd = XtVaCreateManagedWidget ( argv[1], xmPushButtonWidgetClass, commands, NULL );

     XtAddCallback ( cmd, XmNactivateCallback, cmdCallback, ( XtPointer ) argv[1] );

 

 

 

 

     XtRealizeWidget ( shell );

     XtAppMainLoop ( app );

}

 

void cmdCallback ( Widget w, XtPointer clientData, XtPointer callData )

{

     char * cmd = (char *) clientData;

     system ( cmd );

}

 

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

{

     exit ( 0 );

}

 

Solution Q4.c: