echo colored text in a shell script?

Color text is done by embedded escape characters in the text. This makes it really hard to visualize when typing, but it's possible.

The sequence starts with "Ctrl-v ESC [", that is type Ctrl-v followed by the Escape key (which will appear as ^[ ) followed by left bracket. You then specify one or two numbers in the form:

ab

where a = 3 to define the foreground (text) color and a=4 to set the background color, and b is one of the following:

0 = black
1 = red
2 = green
3 = yellow
4 = blue
5 = magenta
6 = cyan
7 = white

So 30;42 would print red text (31) on a green background (42), and 36;40 would print cyan text on a black background, and so on.

You then print 'm' followed by the text. You should follow the string by ^[[0m to reset the colors back to default (otherwise the same color scheme would continue to be used for all subsequent text.

So, as an example, you could:

echo "^[[31;43mWarning^[[0m"

(remembering that ^[ is entered as 'Ctrl-v ESC')

This would print 'Warning' in red text on a yellow background.

(There is one further set of attributes you can use to print bold, underlined or flashing text - just try prepending a single digit before the colors to see what effects you can get)

Just bear in mind that different shells and different terminals may interpret the codes differently (or have a different set altogether - the above is based on the ANSI standard, but VT100 works differently.

The following is a shell script that displays the terminal colors and the escape sequences used to generate them:

#!/bin/sh
#-----------------------------------------------------------------------------
# colors.esc - display the terminal colors and the escape sequences that
# generate them. "Blink" is _NOT_ shown, as it is a very
# annoying effect, and should be avoided at all costs in normal
# daily uses.
# 
# Usage: colors.esc [12 character or less display string]
#-----------------------------------------------------------------------------
# Bob Harris
#-----------------------------------------------------------------------------
E=$(printf ' ') # escape <E>
R="${E}[0m" # reset <E>[0m
typeset dsp_str=""
typeset dsp_txt
typeset fg_text
typeset bg_text
if [[ $# != 0 ]]; then
 dsp_str=$(printf "%12.12s" "$*")
fi
color=(Black Red Green Yellow Blue Magenta Cyan White)
for bg in "" 0 1 2 3 4 5 6 7 # for each background color
do
 b=$bg && [[ X$b != X ]] && b="4$b;" # deal with no background color ""
 echo " ------------ ----bold---- -underline-- --reverse---"
 for fg in 0 1 2 3 4 5 6 7 # for each foreground color
 do
 f="3$fg" # setup foreground color
 line=""
 for a in "" 1 4 7 # for each attribute
 do
 [[ X$a != X ]] && a=";$a" # deal with no attribute ""
 if [[ -z "$dsp_str" ]]; then
 dsp_txt=$(printf "%12s" "<E>[${b}${f}${a}m") # build esc text
 else
 dsp_txt="$dsp_str" # use supplied text
 fi
 line="${line}${E}[${b}${f}${a}m${dsp_txt}${R} " # build entry
 done
 fg_text=$(printf "%-7s" ${color[$fg]}) # translate foreground color
 bg_text=$(printf "%-9s" "Bg${color[$bg]}") # translate background color
 [[ X$b = X ]] && bg_text=$(printf "%-9s" " ") # no bckgnd color
 line="$bg_text $fg_text $line" # build final display line
 echo "${line% }" # display the colorized line
 done
done
 echo " ------------ ----bold---- -underline-- --reverse---"
bg_text=$(printf "%-9s" " ")
fg_text=$(printf "%-7s" "Reset")
dsp_txt=$(printf "%12s" "<E>[0m")
line="$bg_text $fg_text $dsp_txt" # build final display line
echo "${line% }"

The pico help ^G says:

pressing Esc twice and then typing a three-digit decimal number from 000 to 255 will enter the character with the corresponding value.

Although I really do not use pico, so your mileage may vary.

Or you can use the following in a shell script for escape:

printf " "
# or
echo -e " "

for example:

echo -e " [31mRed [m"
# or
printf " [31m"
printf "Red text that you want to see"
printf " [m"
printf " "

One simplification would be to create variables with the escape codes in the variable:

RED=$(printf " [31m")
RESET=$(printf " [m")
echo "${RED}Some Red Text${RESET}"

Not all "shell scripts" are equivalent.

#!/usr/bin/perl -w
use strict;
use Term::ANSIColor;
print color 'red';
print "Hello Color World! ";
print color 'reset';