Sunday, 22 March 2020

Color code in Linux shell

Color modes, colors for bash prompt, tput and ANSI color 

Setting colors in terminal session is only temporary and relatively unconditional.
Modern systems usually default to at least xterm-256color.

$ echo $TERM
xterm (old)

Check current settings

$ echo $LS_COLORS
rs=0:di=01;34:ln=01;36:mh=00:pi=40;
33:so=01;35:do=01;35:bd=40;33;01:cd=40;
[...]

$ dircolors --print-database
[...].jpg 01;35
.jpeg 01;35
.gif 01;35[...]

$ dircolors --bourne-shell
LS_COLORS='rs=0:di=01;34:ln=01;36:mh=00:pi=40;
33:so=01;35:do=01;35:bd=40;33;01:cd=40;
[...]

The Color modes:

1. Color-mode

It modifies the style of color NOT text. For example make the color bright or darker.

0; reset
1; lighter than normal
2; darker than normal
This mode is not supported widely. It is fully support on Gnome-Terminal.

2. Text-mode

This mode is for modifying the style of text NOT color.

3; italic
4; underline
5; blinking (slow)
6; blinking (fast)
7; reverse
8; hide
9; cross-out
and are almost supported.
For example KDE-Konsole supports 5; but Gnome-Terminal does not and Gnome supports 8; but KDE does not.

3. Foreground mode
This mode is for colorizing the foreground.

4. Background mode
This mode is for colorizing the background.

Colors to current BASH prompt (PS1)

To add colors to the shell prompt use the following export command syntax:
'\e[x;ym $PS1 \e[m'
Where,

\e[ : Start color scheme.
x;y : Color pair to use (x;y)
$PS1 : Your shell prompt variable.
\e[m : Stop color scheme.

Examples using export and tput,
$ export PS1="\e[0;31m[\u@\h \W]\$ \e[m "
$ export PS1="\[$(tput setaf 2)\]\u@\h:\w $ \[$(tput sgr0)\]"

tput

Foreground & background colour commands
tput setab [1-7] # Set the background colour using ANSI escape
tput setaf [1-7] # Set the foreground colour using ANSI escape

Colours are as follows:

No  Colour      #define              R G B

0    black       COLOR_BLACK       0,0,0
1    red           COLOR_RED          1,0,0
2    green       COLOR_GREEN       0,1,0
3    yellow      COLOR_YELLOW    1,1,0
4    blue          COLOR_BLUE        0,0,1
5    magenta   COLOR_MAGENTA  1,0,1
6    cyan         COLOR_CYAN        0,1,1
7    white        COLOR_WHITE      1,1,1

Text mode commands
tput bold    # Select bold mode
tput dim     # Select dim (half-bright) mode
tput smul    # Enable underline mode
tput rmul    # Disable underline mode
tput rev     # Turn on reverse video mode
tput smso    # Enter standout (bold) mode
tput rmso    # Exit standout mode

echo "$(tput setaf 1)Red text $(tput setab 7)and white background$(tput sgr 0)"

Color summary


ANSI Color variables












Code  Effect

  0       reset
  1       lighter than normal
  2       darker than normal
  3       italic
  4       underline
  5       blinking (slow)
  6       blinking (fast)
  7       reverse
  8       hide
  9       cross-out


































# Reset
Color_Off='\033[0m'       # Text Reset

# Regular Colors
Black='\033[0;30m'        # Black
Red='\033[0;31m'          # Red
Green='\033[0;32m'        # Green
Yellow='\033[0;33m'       # Yellow
Blue='\033[0;34m'         # Blue
Purple='\033[0;35m'       # Purple
Cyan='\033[0;36m'         # Cyan
White='\033[0;37m'        # White

# Bold
BBlack='\033[1;30m'       # Black
BRed='\033[1;31m'         # Red
BGreen='\033[1;32m'       # Green
BYellow='\033[1;33m'      # Yellow
BBlue='\033[1;34m'        # Blue
BPurple='\033[1;35m'      # Purple
BCyan='\033[1;36m'        # Cyan
BWhite='\033[1;37m'       # White

# Underline
UBlack='\033[4;30m'       # Black
URed='\033[4;31m'         # Red
UGreen='\033[4;32m'       # Green
UYellow='\033[4;33m'      # Yellow
UBlue='\033[4;34m'        # Blue
UPurple='\033[4;35m'      # Purple
UCyan='\033[4;36m'        # Cyan
UWhite='\033[4;37m'       # White

# Background
On_Black='\033[40m'       # Black
On_Red='\033[41m'         # Red
On_Green='\033[42m'       # Green
On_Yellow='\033[43m'      # Yellow
On_Blue='\033[44m'        # Blue
On_Purple='\033[45m'      # Purple
On_Cyan='\033[46m'        # Cyan
On_White='\033[47m'       # White

# High Intensity
IBlack='\033[0;90m'       # Black
IRed='\033[0;91m'         # Red
IGreen='\033[0;92m'       # Green
IYellow='\033[0;93m'      # Yellow
IBlue='\033[0;94m'        # Blue
IPurple='\033[0;95m'      # Purple
ICyan='\033[0;96m'        # Cyan
IWhite='\033[0;97m'       # White

# Bold High Intensity
BIBlack='\033[1;90m'      # Black
BIRed='\033[1;91m'        # Red
BIGreen='\033[1;92m'      # Green
BIYellow='\033[1;93m'     # Yellow
BIBlue='\033[1;94m'       # Blue
BIPurple='\033[1;95m'     # Purple
BICyan='\033[1;96m'       # Cyan
BIWhite='\033[1;97m'      # White

# High Intensity backgrounds
On_IBlack='\033[0;100m'   # Black
On_IRed='\033[0;101m'     # Red
On_IGreen='\033[0;102m'   # Green
On_IYellow='\033[0;103m'  # Yellow
On_IBlue='\033[0;104m'    # Blue
On_IPurple='\033[0;105m'  # Purple
On_ICyan='\033[0;106m'    # Cyan
On_IWhite='\033[0;107m'   # White


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