TrinityCoder/center_text_in_bash.md

## center_text_in_bash.md

      
    Raw
  

              center_text_in_bash.md
            
          
    Sometimes we might want to print some text in Bash and we might want it to be centered
to the centre of the terminal. It is a cheap way how we can increase clarity of
output of our script and make it look much more attractive.
The whole magic is hidden in a program called tput.
To get number of rows and cols of current terminal, we need just two simple shell substitutions:
    TERM_ROWS="$(tput rows)"
    TERM_COLS="$(tput cols)"
For centering our arbitrary text to the middle of the terminal, we actually only need to know
the value of TERM_COLS. So we are already ready to go!
How to do it

Without further comments, I present here a simple bash function called print_centered,
which awaits one or two arguments. The first argument is a string to be centered,
the second argument is a character that should fill the rest of the line.
Default filling character is -
function print_centered {
     [[ $# == 0 ]] && return 1

     declare -i TERM_COLS="$(tput cols)"
     declare -i str_len="${#1}"
     [[ $str_len -ge $TERM_COLS ]] && {
          echo "$1";
          return 0;
     }

     declare -i filler_len="$(( (TERM_COLS - str_len) / 2 ))"
     [[ $# -ge 2 ]] && ch="${2:0:1}" || ch=" "
     filler=""
     for (( i = 0; i < filler_len; i++ )); do
          filler="${filler}${ch}"
     done

     printf "%s%s%s" "$filler" "$1" "$filler"
     [[ $(( (TERM_COLS - str_len) % 2 )) -ne 0 ]] && printf "%s" "${ch}"
     printf "\n"

     return 0
}
And this is how it can look in real usage:
------------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------
                 Building local Jekyll project in: /home/user/jekyll/example.com                 
------------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------
Configuration file: /home/user/jekyll/example.com/_config.yml
            Source: /home/user/jekyll/example.com
       Destination: /home/user/jekyll/example.com/_site
 Incremental build: disabled. Enable with --incremental
      Generating... 
                    done in 0.21 seconds.
 Auto-regeneration: disabled. Use --watch to enable.
The first five lines are printed by print_centered function. The first two
and last two are printed using command
print_centered "-" "-"

which centers one - at the middle of the terminal and fills the rest of line
with the same character - an easy way to achieve a "horizontal bar".
If you have any questions about this, feel free to ask in comments.