if(openpty(&master, &slave, slave_name, &term.conf, &term.ws_conf)<0) { 
 perror("openpty");
 exit(0);
}
printf("pty: %s\n", slave_name);
signal(SIGIO, io);
fcntl(master, F_SETFL, fcntl(master, F_GETFL,0)|O_ASYNC|O_NONBLOCK);
if(fork() == 0) {
 login_tty(slave);
 execlp("/bin/ksh", "ksh", (char *)0);
}
... do master stuff

#!/bin/bash

# Script to randomly set Background from files in a directory

#hopefully set some of the environment variables properly...
#/home/zandi/.profile

# Directory Containing Pictures
DIR="/home/zandi/Pictures/space"
#DISPLAY=:0.0
#USER=zandi
#USERNAME=zandi

# Command to Select a random jpg file from directory
# Delete the *.jpg to select any file but it may return a folder
PIC=$(ls $DIR/*.jpg | shuf -n1)

#set the wallpaper
/usr/bin/gconftool -t string -s /desktop/gnome/background/picture_filename $PIC

-rwsr-xr-x 1 zandi zandi      519 2010-02-23 21:23 wallpaper.sh

* * * * * /home/zandi/wallpaper.sh >/tmp/cron.log 2&>1