How to retain grep color when storing in variable or piping to another command?

Question

I'm wanting to use the grep in a bash script to find matching lines in a file, highlight the matches with color, and then print out the results in a table using the column command. Something like this:

data=`cat file.data | egrep -i --color "$search"`
echo $'\n'"col1"$'\t'"col2"$'\t'"col3"$'\t'"col4"$'\n'"$data" | column -t -s$'\t'

The above code does everything as desired, except that the color is lost.

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Here's a simplified example:

As you can see, when I used grep the results were printed on individual lines and in color, but when I save the results to a variable and then print the variable out, the line breaks and colors are gone.

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Is there any way to do what I'm asking?

Answer 1

Use the option --color=always:

data=$(egrep -i --color=always "$search" file.data)

By default, grep does not produce color unless the output is going directly to a terminal. This is normally a good thing. The option --color=always overrides that.

For occasions when you don't want color, use --color=never.