How display color message from bash script?

Question

I found this example:

echo -e "This is red->\e[00;31mRED\e[00m"

It works if execute direct, from command line, bu if create file like:

#! /usr/bin/sh
echo -e "This is red->\e[00;31mRED\e[00m"

Doesn't work. How to fix? Or may be possible output in bold? Please don't use Lua it doesn't installed.

Answer 1

Edit This might be your problem (likely):

#!/bin/bash
echo -e "This is red->\e[00;31mRED\e[00m"

The reason is that sh doesn't have a builtin echo command, that supports escapes.

Alternatively you might invoke your script like

bash ./myscript.sh

---

Backgrounders

ANSI escape sequences are interpreted by the terminal.

If you run in a pipe/with IO redirected, ouput won't be to a terminal, hence the escapes don't get interpreted.

Hints:

• see ansifilter for a tool that can filter ANSI escape sequences (and optionally translate to HTML and others)

• use GNU less, e.g. to get ANSI escapes working in a pager:

  grep something --colour=always files.* | less -R
  

Or simply, as I do

# also prevent wrapping long lines
alias less='less -SR'

Answer 2

Use an echo program, not an echo built-in command:

#!/bin/sh
MYECHO="`which echo`"
if <test-whether-MYECHO-empty-and-act-accordingly> ...
...
$MYCHO -e "This is red->\e[00;31mRED\e[00m"