Suppose you have an alias on you .bashrc alias shutdown="sudo shutdown -h now" and you would like to confirm the execution.
The following script executes any console, alias or gui program with an extra dialog before execution.
Usage:
tkdialog shutdown
Make sure to 'chmod +x' and put the file into you executables path like /usr/local/bin.
Here is the code:
#!/bin/wish
package require Tk
set msg ""
wm withdraw .
bind . <Escape> {exit}
set answer [tk_messageBox -type yesno -icon question -message "Do you really want to $argv?" -parent .]
if {$answer=="yes"} { catch { exec zsh -i -c "$argv"} msg }
exit