Bash script to print a text file in color

Question

I have a text file with three paragraphs. I want to display the different paragraphs in different colors using bash script commands. Paragraph 1 in red, paragraph 2 in blue and paragraph 3 in cyan.

I managed to display lines in color using commands like

echo -e '\E[32;47m Green.'; tput sgr0

However, I want to parse my file and change colors when there is a new paragraph. I would appreciate for some hints.

Answer 1

Here's an awk solution, which uses in turn elements of an array of color settings:

BEGIN { nc = split("\33[31;47m \33[34;43m \33[36;40m", colors, " ");
        c=1; print colors[c] }
{ print }
/^$/ { c = 1+(c%nc); print colors[c]}

[Edit: The above erroneously adds an extra blank line between paragraphs. Corrected code is as follows:

BEGIN { nc = split("\33[31;47m \33[34;43m \33[36;40m", colors, " ");
        c=1; printf "%s", colors[c] }
/^$/ { c = 1+(c%nc); print colors[c]}
!/^$/

The !/^$/ causes any non-blank line to print as is. (End Edit)].

If the above is in file 3-para.awk and data is in file 3-para.data, use a command like awk -f 3-para.awk 3-para.data to get output like the following.

For more convenient use, define a function that invokes the script and then resets colors to default:

tricolor() {
   awk -f 3-para.awk $1; tput sgr0
}

Use the function via (eg) tricolor 3-para.data

Answer 2

The input /tmp/FILE : http://pastie.org/4928415

The script :

#!/bin/bash

c=1
tput setaf $c
while read a; do
    [[ $a =~ ^$ ]] && tput setaf $((++c))
    echo "$a"
done < /tmp/FILE
tput sgr0

The output :