How to change the output color of echo in Linux

Question

I am trying to print a text in the terminal using echo command.

I want to print the text in a red color. How can I do that?

Answer 1

We can use 24 Bits RGB true colors for both text and background!

 ESC[38;2;⟨r⟩;⟨g⟩;⟨b⟩m  /*Foreground color*/
 ESC[48;2;⟨r⟩;⟨g⟩;⟨b⟩m  /*Background color*/

Example red text and closing tag:

 echo -e "\e[38;2;255;0;0mHello world\e[0m"

Generator:

text.addEventListener("input",update)
back.addEventListener("input",update)

function update(){
  let a = text.value.substr(1).match(/.{1,2}/g)
  let b = back.value.substr(1).match(/.{1,2}/g)
  out1.textContent = "echo -e \"\\" + `033[38;2;${parseInt(a[0],16)};${parseInt(a[1],16)};${parseInt(a[2],16)}mHello\"`
  out2.textContent = "echo -e \"\\" + `033[48;2;${parseInt(b[0],16)};${parseInt(b[1],16)};${parseInt(b[2],16)}mWorld!\"`
}

div {padding:1rem;font-size:larger}

TEXT COLOR: 


BACK COLOR: 

24-bit: As "true color" graphic cards with 16 to 24 bits of color became common, Xterm,KDE's Konsole, as well as all libvte based terminals (including GNOME Terminal) support 24-bit foreground and background color setting https://en.wikipedia.org/wiki/ANSI_escape_code#24-bit

Is it safe to use in my scripts?

Yes! 8 and 16 bits terminals will just display as fallback a color on the range of the available palette, keeping the best contrast, no breakages!

---

Also, nobody noticed the usefulness of the ANSI code 7 reversed video.

It stay readable on any terminal schemes colors, black or white backgrounds, or other fancies palettes, by swapping foreground and background colors.

Example, for a red background that works everywhere:

echo -e "\033[31;7mHello world\e[0m";

This is how it looks when changing the terminal built-in schemes:

This is the loop script used for the gif.

for i in {30..49};do echo -e "\033[$i;7mReversed color code $i\e[0m Hello world!";done

See https://en.wikipedia.org/wiki/ANSI_escape_code#SGR_(Select_Graphic_Rendition)_parameters