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!
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:
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Building local Jekyll project in: /home/user/jekyll/example.com
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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.
Hey,
Love this function.
Quick question, I'm new to tput. How would i centre the menu in the screen but align menu number?
Thanks
Chris