Bash Dynamic command line output

Question

I was wondering how to get dynamic output in a shell. I mean the kind of output you get with "top" command or the status bar for wget downloads: the command line output changes without any newline.

my specific needs are to get a feedback from a script (which takes a lot to be executed with a lot of operations) without getting a newline for every single operation feedback for example a discovery script which send pings in a very large network and can dynamically tell the status of the discovery.

(no I cannot use nmap :D anyway it is for study purpose)

thanks!

Related: stackoverflow.com/questions/8547033/…

tripleee
– tripleee

2015-07-01 08:51:58 +00:00
Commented Jul 1, 2015 at 8:51 — tripleee
– tripleee, Commented Jul 1, 2015 at 8:51
Maybe this can serve as a starting point.

Eugeniu Rosca
– Eugeniu Rosca

2015-07-01 08:54:25 +00:00
Commented Jul 1, 2015 at 8:54 — Eugeniu Rosca
– Eugeniu Rosca, Commented Jul 1, 2015 at 8:54

tripleee · Accepted Answer · 2015-07-01 09:22:59Z

3

The "dynamic" display is just a sequence of print statements. Some of those print statements print screen control codes which move the cursor or repaint parts of the screen. The de facto standard framework for this is ncurses. For access from within a shell script, you want tput.

Here is a simple "animated" spinner.

#!/bin/sh

# Restore cursor and move to new line when terminated
trap 'tput cnorm; echo' EXIT
trap 'exit 127' HUP INT TERM

# Make text cursor invisible
tput civis
# Save cursor position
tput sc
while true; do
  for char in '-' '\' '|' '/'; do
    # Back to saved position
    tput rc
    printf "%s" "$char"
    sleep 1
  done
done

edited Jul 1, 2015 at 9:22

answered Jul 1, 2015 at 8:50

tripleee

192k37 gold badges318 silver badges367 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

123 Over a year ago

Yep tput and stty are great for this.

lcd047 · Accepted Answer · 2015-07-01 10:53:08Z

1

You can use cursor movement with bash. For cursor movements refer to http://tldp.org/HOWTO/Bash-Prompt-HOWTO/x361.html

If say you want to print dates dynamically, you can have something like this:

echo -ne '\033[s'; clear ; for i in `seq 10`;do echo -ne '\033[0;0H' ; date;sleep 1;done ;echo -ne '\033[u'

edited Jul 1, 2015 at 10:53

lcd047

5,8712 gold badges32 silver badges40 bronze badges

answered Jul 1, 2015 at 9:02

Abubaker Siddique

13911 bronze badges

Collectives™ on Stack Overflow

Bash Dynamic command line output

2 Answers 2

1 Comment

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related