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

In case you have to show a temporal progress bar (by knowing in advance the showing time), you can use Python as follows:

#!/bin/python
from time import sleep
import sys

if len(sys.argv) != 3:
    print "Usage:", sys.argv[0], "", ""
    exit()

TOTTIME=float(sys.argv[1])
BARSIZE=float(sys.argv[2])

PERCRATE=100.0/TOTTIME
BARRATE=BARSIZE/TOTTIME

for i in range(int(TOTTIME)+1):
    sys.stdout.write('\r')
    s = "[%-"+str(int(BARSIZE))+"s] %d%% "
    sys.stdout.write(s % ('='*int(BARRATE*i), int(PERCRATE*i)))
    sys.stdout.flush()
    SLEEPTIME = 1.0
    if i == int(TOTTIME): SLEEPTIME = 0.1
    sleep(SLEEPTIME)
print ""

Then, assuming you saved the Python script as progressbar.py, it's possible to show the progress bar from your bash script by running the following command:

python progressbar.py 10 50

It would show a progress bar sized 50 characters and "running" for 10 seconds.