bash - 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 big file, opening a big tar file.

What ways do you recommend to add progress bars to shell scripts?

Answer 1

You can implement this by overwriting a line. Use to go back to the beginning of the line without writing to the terminal.

Write when you're done to advance the line.

Use echo -ne to:

1. not print and
2. to recognize escape sequences like .

Here's a demo:

echo -ne '#####                     (33%)
'
sleep 1
echo -ne '#############             (66%)
'
sleep 1
echo -ne '#######################   (100%)
'
echo -ne '
'

In a comment below, puk mentions this "fails" if you start with a long line and then want to write a short line: In this case, you'll need to overwrite the length of the long line (e.g., with spaces).