How to Use Colors in Bash Scripts Made Simple
Color can be added to a terminal window output in Bash scripts using escape codes. Note that the effects will differ depending on the client program being used to connect. The examples below were executed via a Putty ssh terminal.
Bash Color Codes
- There are foreground colors, background colors, and text styles
- Not all are supported based on the client terminal program!
- Color codes are based on special “escape sequences” (such as “\e[32m” for Green)
- Use “echo -e” to have Bash properly interpret the escape code:
$ echo -e "\e[31mRed Text!"
- Finally, if you wish to turn off a color or style, use the appropriate reset code:
$ echo -e "\e[93m\e[46mYellow on Cyan\e[0m Normal"
- Note that the background wasn’t explicitly turned off… the “0” value resets everything
A Simple Color Script to be Included in Bash Scripts
The following script provides color constants that can be quickly used in your Bash scripts.
- Save the script below as “colors.sh“
- Place the script somewhere on your path (when I wrote this, it was originally for admin scripts and I placed it in /usr/sbin)
- Include it in your bash script by adding this line:
source colors.sh
- Be sure to change permissions to allow execution:
$ chmod 755 colors.sh
- The script has a test function labelled “func_cdisplay” which outputs foreground/background combinations
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# colors.sh
# Version KAS 150412
# This script defines a set of constants for foreground colors,
# background colors, and console text styles to be used in bash
# console scripts.
#
# To use this script:
#
# In your bash script, near the top, add:
# source colors.sh
#
# Use echo -e to handle escape codes, and use ${constant} to
# insert a color code:
# echo -e ${cdc}This is dark cyan.${coff}
#
# Use the Color Off constant "coff", the Background Color Off
# constant "boff" and the Style Off constant "soff" to clear
# formatting:
# echo -e ${cly}${bdb}Classic ${sun}Yellow${sunf} on Blue${coff}
#
# Codes are abbreviated for quick insertion. Abbreviation format:
# 1st: c: color b: background color s: style
# 2nd: l: light d: dark
# rest: color / style
# Foreground (Text) Colors
cbl="\e[30m" # Color Black
cdr="\e[31m" # Color Dark Red
cdg="\e[32m" # Color Dark Green
cdy="\e[33m" # Color Dark Yellow
cdb="\e[34m" # Color Dark Blue
cdm="\e[35m" # Color Dark Magenta
cdc="\e[36m" # Color Dark Cyan
clgy="\e[37m" # Color Light Gray
cdgy="\e[90m" # Color Dark Gray
clr="\e[91m" # Color Light Red
clg="\e[92m" # Color Light Green
cly="\e[93m" # Color Light Yellow
clb="\e[94m" # Color Light Blue
clm="\e[95m" # Color Light Magenta
clc="\e[96m" # Color Light Cyan
cwh="\e[97m" # Color White
# Turns off all formatting
coff="\e[0m" # Color Off
# Background Colors
bbl="\e[40m" # Background Color Black
bdr="\e[41m" # Background Color Dark Red
bdg="\e[42m" # Background Color Dark Green
bdy="\e[43m" # Background Color Dark Yellow
bdb="\e[44m" # Background Color Dark Blue
bdm="\e[45m" # Background Color Dark Magenta
bdc="\e[46m" # Background Color Dark Cyan
blgy="\e[47m" # Background Color Light Gray
bdgy="\e[100m" # Background Color Dark Gray
blr="\e[101m" # Background Color Light Red
blg="\e[102m" # Background Color Light Green
bly="\e[103m" # Background Color Light Yellow
blb="\e[104m" # Background Color Light Blue
blm="\e[105m" # Background Color Light Magenta
blc="\e[106m" # Background Color Light Cyan
bwh="\e[107m" # Background Color White
# Turns off only the background color
boff="\e[49m" # Background Color Off
# Styles
sbo="\e[1m" # Style Bold
sdi="\e[2m" # Style Dim
sun="\e[4m" # Style Underline
sbl="\e[5m" # Style Blink
sre="\e[7m" # Style Reverse
shi="\e[8m" # Style Hidden
sbof="\e[21m" # Style Bold Off
sdif="\e[22m" # Style Dim Off
sunf="\e[24m" # Style Underline Off
sblf="\e[25m" # Style Blink Off
sref="\e[27m" # Style Reverse Off
shif="\e[28m" # Style Hidden Off
# A test function which illustrates combinations
func_cdisplay ()
{
local text="MXW"
local formatted=""
local colors=( $cbl $cdr $cdg $cdy $cdb $cdm $cdc $clgy \
$cdgy $clr $clg $cly $clb $clm $clc $cwh )
local bgs=( $bbl $bdr $bdg $bdy $bdb $bdm $bdc $blgy \
$bdgy $blr $blg $bly $blb $blm $blc $bwh )
for color in ${colors[@]}
do
for bg in ${bgs[@]}
do
formatted=" $formatted ${bg}${color}${text}${coff}"
done
echo -e $formatted
formatted=""
done
echo
echo -e "${sbo}Bold${sbof} ${sdi}Dim${sdif} " \
"${sun}Underline${sunf} ${sbl}Blink${sblf} " \
"${sre}Reverse${sref} .${shi}Hidden${shif}."
echo
}
The following is example output of the “func_cdisplay” function on a Putty ssh session window:
Some styles aren’t supported, such as Blink or Hidden. It is a good idea to call “func_cdisplay” under your client to see what is supported and what the best combinations are.
That’s it.
k
