Bash script

gacanepa · 07-17-2012, 03:46 PM

Hi all,
I would like to know if it is possible to center some text on the screen using a bash script.
Example:

Code:

#!/bin/bash
echo "Centered text"

I can add spaces before and after the text string to try to manually center it (but this would sort of work only for a certain screen resolution), but it won't look as good as if there is something that can be inserted in the code that will work with all screen resolutions.
Suggestions are welcome! Thanks in advance.

Kustom42 · 07-17-2012, 03:50 PM

You may be able to use tputs for this, tputs is very powerful in regards to terminal control. I have never used it for this purpose but reviewing some tputs tutorials may help you.

I'm going to do some searching and see if I can find you the answer. I have used tputs previously to move the cursor to top left of terminal, then back down to bottom right, etc..

Kustom42 · 07-17-2012, 03:52 PM

Here's some stuff to look over, you will likely have to use the x,y coordinates with tputs to specify where you want it to go...

http://tldp.org/HOWTO/Bash-Prompt-HOWTO/x405.html

whizje · 07-17-2012, 03:57 PM

With stty size you can get the dimensions of your terminal

Code:

bash-4.2# stty size
41 80

gacanepa · 07-17-2012, 04:15 PM

I will look up the information you guys just shared! Thanks a lot for taking the time to write.
Nevertheless, just playing with coordinates will not quite work in all instances.
I found the following in YouTube:
1) Assign a text string to a variable, let's say title="Hello world!"
2) printf "%*s\n" $(((${#title}+$COLUMNS)/2)) "$title" will output
Hello world! centered in the screen, regarding of its resolution.

Kustom42 · 07-17-2012, 04:24 PM

That print statement also has its limitations in the fact that you are using columns. Using perl or something more robust than BASH would allow you to create the script to always display the same way, regardless of the size of the terminal.

gacanepa · 07-17-2012, 06:06 PM

Quote:

Originally Posted by Kustom42

That print statement also has its limitations in the fact that you are using columns. Using perl or something more robust than BASH would allow you to create the script to always display the same way, regardless of the size of the terminal.

You were right about that my friend. The printf statement does have its limitations... that sample script only works in the terminal but it doesn't inside a shell script. The following script that uses tput does the job:

Code:

#!/bin/bash -i
  #Menú de programa centrado
  titulo="Menú principal"
  clear
  ast="*********************************************************"
  columnas=$(tput cols)
  y=$((($columnas-${#ast})/2))
  x=0
  tput clear
  tput cup $x $y
  echo "${ast}"
  echo ""
  y=$((($columnas-${#titulo})/2))
  x=1
  tput cup $x $y
  echo "${titulo}"
  echo ""
  y=$((($columnas-${#ast})/2))
  x=2
  tput cup $x $y
  echo "${ast}"

Prints the following, centered in the screen:
*********************************************************
Menú principal
*********************************************************

TobiSGD · 07-17-2012, 06:18 PM

If you want to put formatted text, like menus, textboxes, etc.. on the screen then maybe dialog is an option for you, it also simplifies the input handling.

Kustom42 · 07-17-2012, 07:51 PM

Good point on dialog and nice way to script it, the division method should ensure that it stays centered on most every sized terminal.