How to add a progress bar to a shell script?

Question

When scripting in bash or any other shell in *NIX, while running a command that will take more than a few seconds, a progress bar is needed.

For example, copying a b

Answer 1

This is only applicable using gnome zenity. Zenity provides a great native interface to bash scripts: https://help.gnome.org/users/zenity/stable/

From Zenity Progress Bar Example:

#!/bin/sh
(
echo "10" ; sleep 1
echo "# Updating mail logs" ; sleep 1
echo "20" ; sleep 1
echo "# Resetting cron jobs" ; sleep 1
echo "50" ; sleep 1
echo "This line will just be ignored" ; sleep 1
echo "75" ; sleep 1
echo "# Rebooting system" ; sleep 1
echo "100" ; sleep 1
) |
zenity --progress \
  --title="Update System Logs" \
  --text="Scanning mail logs..." \
  --percentage=0

if [ "$?" = -1 ] ; then
        zenity --error \
          --text="Update canceled."
fi