Shell Programming and Scripting

Code:

 dialog --title "Inputbox - To take input from you" --backtitle "Linux Shell\
 Script Tutorial" --inputbox "Enter your name please" 8 60 2>/tmp/input.$$

 sel=$?

 na=`cat /tmp/input.$$`
 case $sel in
   0) echo "Hello $na" ;;
   1) echo "Cancel is Press" ;;
   255) echo "[ESCAPE] key pressed" ;;
 esac

 rm -f /tmp/input.$$

What does it mean by $$?

Pid of the current/parrent shell.

Would you please explain some lines?

Code:

dialog --title "Inputbox - To take input from you" --backtitle "Linux Shell\
 Script Tutorial" --inputbox "Enter your name please" 8 60 2>/tmp/input.$$

 na=`cat /tmp/input.$$`
 rm -f /tmp/input.$$

What would I please? I don't understand you.

Sorry.Edited.
It was "Explain".

I don't know a tool called "dialog". It seems it handles some kind of input and output, like the text that offers some description and asks for a name which could have a space of 8 characters and maybe a length of 80. I am guessing around - check if you have a man page for that on your system.

What I recognize is the redirection of STDERR with 2> which is written to some temp file that has the parent shell's PID in it's filename.

Variable "na" is defined with the content of the temp file. After that the temp file is removed.

No offense but you should generally have a look into this:
Linux Shell Scripting Tutorial - A Beginner's handbook

Thank you for your reply.
I also have taken that code from that site you gave.
LSST v1.05r3 > Chapter 4 > Input Box (inputbox) using dialog utility