ShellHacks
Command-Line Tips and Tricks

    Blog

Bash Colors
Posted on December 27, 2016by admin

You can make your BASH script more pretty, by colorizing its output.

Use ANSI escape sequences to set text properties like foreground and background colors.
Colorizing Shell

Use the following template for writing colored text:

echo -e "\e[COLORmSample Text\e[0m"

Option 	Description
-e 	Enable interpretation of backslash escapes
\e[ 	Begin the color modifications
COLORm 	Color Code + ‘m’ at the end
\e[0m 	End the color modifications

Examples:

$ echo -e "\e[31mRed Text\e[0m"
Red Text
$ echo -e "\e[42mGreen Background\e[0m"
Green Background

ANSI — Color Escape Codes

Shell scripts commonly use ANSI escape codes for color output:
Color 	Foreground Code 	Background Code 	Sample
Black 	30 	40 	
Red 	31 	41 	
Green 	32 	42 	
Brown 	33 	43 	
Blue 	34 	44 	
Purple 	35 	45 	
Cyan 	36 	46 	
Light Gray 	37 	47 	

Escape sequence also allows to control the manner in which characters are displayed on the screen:
ANSI Code 	Description
0 	Normal Characters
1 	Bold Characters
4 	Underlined Characters
5 	Blinking Characters
7 	Reverse video Characters

Examples:

$ echo -e "\e[1mBold Text\e[0m"
Bold Text
$ echo -e "\e[3mUnderlined Text\e[0m"
Underlined Text

By combining all these escape sequences, we can get more fancy effect.

echo -e "\e[COLOR1;COLOR2mSample Text\e[0m"

There are some differences between colors when combining colors with bold text attribute:
Color 	Foreground Code 	Background Code 	Sample
Dark Gray 	1;30 	1;40 	
Light Red 	1;31 	1;41 	
Light Green 	1;32 	1;42 	
Yellow 	1;33 	1;43 	
Light Blue 	1;34 	1;44 	
Light Purple 	1;35 	1;45 	
Light Cyan 	1;36 	1;46 	
White 	1;37 	1;47 	

Examples:

$ echo -e "\e[1;34mLight Blue Text\e[0m"
Light Blue Text
$ echo -e "\e[1;33;4;44mYellow Underlined Text on Blue Background\e[0m"
Yellow Underlined Text on Blue Background