Color output in console

Related articles

• Emacs#Custom colors and theme
• nano#Syntax highlighting

This page was created to consolidate colorization of CLI outputs.

Background

Escape sequences

The ANSI escape sequences define a way to put additional information into terminal output, and color is part of this "additional information". Throughout the years the range of terminal colors has been vastly expanded, from the initial eight colors to a full 24-bit truecolor.

The basic color encoding provides 8 normal-brightness colors and 8 brighter versions of these colors. Modern terminal emulators, including the Linux console itself, allows you to specify the precise RGB values that the colors translate to. This mode is supported by almost all terminal emulators.

With the advent of 256-color displays came the 256-color escape. The 256 colors are the 16 basic colors, the 216 RGB colors (laid out in a 6x6x6 cube), and 24 levels of greyscale. Except for the first 16 colors, the scheme is usually not customizable as it has a well-defined mapping to RGB. This mode is supported by most terminal emulators. (A minority of emulators use a similar but incompatible encoding with only 88 colors. You are very unlikely to use them in practice, but they will appear in the terminfo database.)

Less commonly supported is the truecolor mode, allowing one to use 16.7 million (2²⁴) colors in RGB (each value ranging from 0 to 255).

Termcap and terminfo

Termcap and terminfo, part of ncurses, are databases that provide information on the escape sequences terminals (usually specified by the TERM env-var) understand. The tput(1) and infocmp(1) commands can be used to access them from command-line.

Applications

diff

diffutils from version 3.4 includes the --color option (GNU mailing list).

$ alias diff='diff --color=auto'

grep

The --color=auto option enables color highlighting. Color codes are emitted only on standard output; not in pipes or redirection.

Color output in grep is also useful with regexp tasks.

Use an alias to permanently enable this option:

alias grep='grep --color=auto'

The GREP_COLORS variable is used to define colors, and it configures various parts of highlighting. To change the colors, find the needed ANSI escape sequence and apply it. See grep(1) § GREP COLORS for more information.

The -n option includes file line numbers in the output.

ip

ip(8) command from iproute2 supports colors with -c option. You can use an alias to enable colored output. When using auto parameter, colored output will be enabled only when stdout is a terminal.

alias ip='ip -color=auto'

less

Environment variables

As with the #man case, we can tell less to emit colors when it is meaning to make bold text and other formatting effects.

Add the following lines to your shell configuration file:

export LESS='-R --use-color -Dd+r$Du+b$'

It will set red for bold and blue for underlined.

For more information about the --use-color and -D options, see less(1) § D or [1].

Reading from stdin

Note: It is recommended to add colored output through #Environment variables to your ~/.bashrc or ~/.zshrc, as the below is based on export LESS='-R'

When you run a command and pipe its standard output (stdout) to less for a paged view (e.g. pacman -Qe | less), you may find that the output is no longer colored. This is usually because the program tries to detect if its stdout is an interactive terminal, in which case it prints colored text, and otherwise prints uncolored text. This is good behaviour when you want to redirect stdout to a file, e.g. pacman -Qe > pkglst-backup.txt, but less suited when you want to view output in less.

Some programs provide an option to disable the interactive tty detection:

# dmesg --color=always | less

In case that the program does not provide any similar option, it is possible to trick the program into thinking its stdout is an interactive terminal with the following utilities:

• ColorThis — Force colored output of a program by running it within a (group of) pty, support forwarding stdin.

https://github.com/Sasasu/ColorThis || colorthis-git^AUR

• stdoutisatty — A small program and a LD_PRELOAD-able library that catches the isatty(3) function call.

https://github.com/lilydjwg/stdoutisatty. || stdoutisatty

Example: stdoutisatty program | less

• unbuffer — A tclsh script comes with expect, it invokes desired program within a pty.

http://expect.sourceforge.net/example/unbuffer.man.html^{[dead link 2024-07-30 ⓘ]} || expect

Example: unbuffer program | less

Alternatively, using zpty module from zsh: [2]

~/.zshrc

zmodload zsh/zpty

pty() {
	zpty pty-${UID} ${1+$@}
	if [[ ! -t 1 ]];then
		setopt local_traps
		trap '' INT
	fi
	zpty -r pty-${UID}
	zpty -d pty-${UID}
}

ptyless() {
	pty $@ | less
}

Usage:

$ ptyless program

To pipe it to other pager (less in this example):

$ pty program | less

ls

The --color=auto option enables color highlighting. Color codes are emitted only on standard output; not in pipes or redirection.

Use an alias to permanently enable this option:

alias ls='ls --color=auto'

The LS_COLORS variable is used to define colors, and it configures various parts of highlighting. Use the dircolors(1) command to set it.

An advanced alternative to dircolors that ships with many themes is the vivid package, see vivid --help for usage.

Note: Using the --color option may incur a noticeable performance penalty when ls is run in a directory with very many entries. The default settings require ls to stat(1) every single file it lists. However, if you would like most of the file-type coloring but can live without the other coloring options (e.g. executable, orphan, sticky, other-writable, capability), use dircolors to set the LS_COLORS environment variable like this:

eval $(dircolors -p | perl -pe 's/^((CAP|S[ET]|O[TR]|M|E)\w+).*/$1 00/' | dircolors -)

See ls(1) for more information.

man

There is a real color facility in grotty(1), but it is strongly discouraged for man pages. Here we fake a colored man by hacking two main pagers, less and most: we replace the sequences for bold, standout, and underline with spiced ones that contain color.

Using bat

bat can be used as a colorizing pager for man, by setting the MANPAGER environment variable as documented here.

Using less

See #less for a more detailed description.

export MANPAGER="less -R --use-color -Dd+r -Du+b"
export MANROFFOPT="-P -c"

For Fish you could accomplish this with:

~/.config/fish/config.fish

set -xU MANPAGER 'less -R --use-color -Dd+r -Du+b'
set -xU MANROFFOPT '-P -c'

Remember to source your config or restart your shell to make the changes take effect.

Using most

The basic function of 'most' is similar to less and more, but it has a smaller feature set. Configuring most to use colors is easier than using less, but additional configuration is necessary to make most behave like less. Install the most package.

Edit /etc/man_db.conf, uncomment the pager definition and change it to:

DEFINE     pager     most -s

Test the new setup by typing:

$ man whatever_man_page

Modifying the color values requires editing ~/.mostrc (creating the file if it is not present) or editing /etc/most.conf for system-wide changes. Example ~/.mostrc:

% Color settings
color normal lightgray black
color status yellow blue
color underline yellow black
color overstrike brightblue black

Using X resources

A quick way to add color to manual pages viewed on xterm/uxterm or rxvt-unicode is to modify ~/.Xresources.

xterm

*VT100.colorBDMode:     true
*VT100.colorBD:         red
*VT100.colorULMode:     true
*VT100.colorUL:         cyan

which replaces the decorations with the colors. Also add:

*VT100.veryBoldColors: 6

if you want colors and decorations (bold or underline) at the same time. See xterm(1) § veryBoldColors for more information.

rxvt-unicode

URxvt.colorIT:      #87af5f
URxvt.colorBD:      #d7d7d7
URxvt.colorUL:      #87afd7

Run:

$ xrdb -load ~/.Xresources

Launch a new xterm/uxterm or rxvt-unicode and you should see colorful man pages.

This combination puts colors to bold and underlined words in xterm/uxterm or to bold, underlined, and italicized text in rxvt-unicode. You can play with different combinations of these attributes. See the sources (archived) of this item.

pacman

Pacman has a color option. Uncomment the Color line in /etc/pacman.conf.

Wrappers

Universal wrappers

(most of them outdated, but still functioning)

They go with multiple preconfigured presets that can be changed, and new ones can be created/contributed.

Warning: Wrappers replace output of commands with escape sequences. Some shell scripts and programs which use the output of standard shell utilities may not work correctly.

• rainbow — Colorize commands output or STDIN using patterns.
  Presets: df, diff, env, host, ifconfig, java-stack-trace, jboss, jonas, md5sum, mvn2, mvn3, ping, tomcat, top, traceroute.

https://github.com/nicoulaj/rainbow || rainbow^AUR

• grc — Yet another colouriser for beautifying your logfiles or output of commands.
  Presets: cat, cvs, df, diff, dig, gcc, g++, ls, ifconfig, make, mount, mtr, netstat, ping, ps, tail, traceroute, wdiff, blkid, du, dnf, docker, docker-machine, env, id, ip, iostat, last, lsattr, lsblk, lspci, lsmod, lsof, getfacl, getsebool, ulimit, uptime, nmap, fdisk, findmnt, free, semanage, sar, ss, sysctl, systemctl, stat, showmount, tune2fs and tcpdump.

https://github.com/garabik/grc || grc

• cope — A colourful wrapper for terminal programs.
  Presets: acpi, arp, cc, df, dprofpp, fdisk, free, g++, gcc, id, ifconfig, ls, lspci, lsusb, make, md5sum, mpc, netstat, nm, nmap, nocope, ping, pmap, ps, readelf, route, screen, sha1sum, sha224sum, sha256sum, sha384sum, sha512sum, shasum, socklist, stat, strace, tcpdump, tracepath, traceroute, w, wget, who, xrandr.

https://github.com/yogan/cope || cope-git^AUR

• cw — A non-intrusive real-time ANSI color wrapper for common unix-based commands. Wraps file which can cause issues.
  Presets: arp, arping, auth.log@, blockdev, cal, cksum, clock, configure, cpuinfo@, crontab@, cw-pipe, cw-test.cgi, date, df, diff, dig, dmesg, du, env, figlet, file, find, finger, free, fstab@, fuser, g++, gcc, group@, groups, hdparm, hexdump, host, hosts@, id, ifconfig, inittab@, iptables, last, lastlog, lsattr, lsmod, lsof, ltrace-color, make, md5sum, meminfo@, messages@, mount, mpg123, netstat, nfsstat, nmap, nslookup, objdump, passwd@, ping, pmap, pmap_dump, praliases, profile@, protocols@, ps, pstree, quota, quotastats, resolv.conf@, route, routel, sdiff, services@, showmount, smbstatus, stat, strace-color, sysctl, syslog, tar, tcpdump, tracepath, traceroute, umount, uname, uptime, users, vmstat, w, wc, whereis, who, xferlog.

https://cwrapper.sourceforge.net/ || cw^AUR

• ccze — A fast log colorizer written in C, intended to be a drop-in replacement for colorize

https://github.com/cornet/ccze/ || ccze^AUR

Libraries for colorizing an output

• libtextstyle — A C library for styling text output to terminals

https://www.gnu.org/software/gettext/libtextstyle/manual/index.html || gettext

• ruby-rainbow — Rainbow is extension to ruby's String class adding support for colorizing text on ANSI terminal

https://rubygems.org/gems/rainbow/ || ruby-rainbow

• python-blessings — A thin, practical wrapper around terminal coloring, styling, and positioning

https://github.com/erikrose/blessings || python-blessings^AUR

• lolcat — Ruby program that makes the output colorful like a rainbow

https://github.com/busyloop/lolcat/ || lolcat

Application specific

Compilers

• colorgcc — A Perl wrapper to colorize the output of compilers with warning/error messages matching the gcc output format

https://schlueters.de/colorgcc.html^{[dead link 2024-03-03 ⓘ]} || colorgcc

diff

Diff has built-in color output, which is reasonable to use. But the following wrappers can be used:

• colordiff — Perl script for diff highlighting.

https://www.colordiff.org/ || colordiff

• cwdiff — (w)diff wrapper with directories support and highlighting.

https://github.com/junghans/cwdiff || cwdiff^AUR

• git-delta — A syntax-highlighting pager for git and diff output.

https://github.com/dandavison/delta || git-delta

cat

• bat — Cat clone with syntax highlighting and git integration.

https://github.com/sharkdp/bat || bat

less

source-highlight

You can enable code syntax coloring in less. First, install source-highlight, then add these lines to your shell configuration file:

~/.bashrc

export LESSOPEN="| /usr/bin/source-highlight-esc.sh %s"
export LESS='-R '

lesspipe

Frequent users of the command line interface might want to install lesspipe.

Users may now list the compressed files inside of an archive using their pager:

$ less compressed_file.tar.gz

==> use tar_file:contained_file to view a file in the archive
-rw------- username/group  695 2008-01-04 19:24 compressed_file/content1
-rw------- username/group   43 2007-11-07 11:17 compressed_file/content2
compressed_file.tar.gz (END)

lesspipe also grants less the ability of interfacing with files other than archives, serving as an alternative for the specific command associated for that file-type (such as viewing HTML via python-html2text).

Re-login after installing lesspipe in order to activate it, or source /etc/profile.d/lesspipe.sh.

Make

• colormake — A simple wrapper around make to make its output more readable.

https://github.com/pagekite/Colormake/ || colormake^AUR

Ping

• prettyping — Add some great features to ping monitoring. A wrapper around the standard ping tool with the objective of making the output prettier, more colorful, more compact, and easier to read.

https://denilson.sa.nom.br/prettyping/ || prettyping

Shells

bash

See Bash/Prompt customization#Colors.

Fish

See Fish#Web interface.

xonsh

See Customizing the Prompt.

zsh

See Zsh#Colors.

Terminal emulators

Virtual console

The colors in the Linux virtual console running on the framebuffer can be changed. This is done by writing the escape code \\e]PXRRGGBB, where X is the hexadecimal index of the color from 0-F, and RRGGBB is a traditional hexadecimal RGB code.

For example, to reuse existing colors defined in ~/.Xresources, add the following to the shell initialization file (such as ~/.bashrc):

if [ "$TERM" = "linux" ]; then
    _SEDCMD='s/.*\*color\([0-9]\{1,\}\).*#\([0-9a-fA-F]\{6\}\).*/\1 \2/p'
    for i in $(sed -n "$_SEDCMD" $HOME/.Xresources | awk '$1 < 16 {printf "\\e]P%X%s", $1, $2}'); do
        echo -en "$i"
    done
    clear
fi

Login screen

The below is a colored example of the virtual console login screen in /etc/issue. Create a backup of the original file with mv /etc/issue /etc/issue.bak as root, and create a new /etc/issue:

\e[H\e[2J
                                                             \e[1;30m| \e[34m\r \s
      \e[36;1m/\\\\                        \e[37m||      \e[36m| =                 \e[30m|
     \e[36m/  \\\\                       \e[37m||      \e[36m|                   \e[30m| \e[32m\t
    \e[1;36m/ \e[0;36m.. \e[1m\\\\   \e[37m//==\\\\\\ ||/= /==\\\\ ||/=\\\\  \e[36m| | |/\\\\ |  | \\\\ /  \e[30m| \e[32m\d
   \e[0;36m/ .  . \\\\ \e[37m||    || ||  ||     ||  ||  \e[36m| | |  | |  |   X   \e[1;30m|
  \e[0;36m/  .  .  \\\\ \e[37m\\\\\\==/| ||   \\\\==/ ||  ||  \e[36m| | |  |\  \\/|  / \\\\ \e[1;30m| \e[31m\U
 \e[0;36m/ ..    .. \\\\   \e[0;37mA simple, lightweight linux distribution.   \e[1;30m|
\e[0;36m/_'        `_\\\\                                              \e[1;30m| \e[35m\l \e[0mon \e[1;33m\n
\e[0m 

See also:

• https://bbs.archlinux.org/viewtopic.php?pid=386429#p386429
• https://www.linuxfromscratch.org/blfs/view/svn/postlfs/logon.html

X window system

Most Xorg terminals, including xterm and urxvt, support at least 16 basic colors. The colors 0-7 are the 'normal' colors. Colors 8-15 are their 'bright' counterparts, used for highlighting. These colors can be modified through X resources, or through specific terminal settings. For example:

~/.Xresources

! Black + DarkGrey
*color0:  #000000
*color8:  #555753
! DarkRed + Red
*color1:  #ff6565
*color9:  #ff8d8d
! DarkGreen + Green
*color2:  #93d44f
*color10: #c8e7a8
! DarkYellow + Yellow
*color3:  #eab93d
*color11: #ffc123
! DarkBlue + Blue
*color4:  #204a87
*color12: #3465a4
! DarkMagenta + Magenta
*color5:  #ce5c00
*color13: #f57900
!DarkCyan + Cyan (both not tango)
*color6:  #89b6e2
*color14: #46a4ff
! LightGrey + White
*color7:  #cccccc
*color15: #ffffff

Warning: Color resources such as foreground and background can be read by other applications (such as emacs). This can be avoided by specifiying the class name, for example XTerm.foreground.

See also:

• #Using X resources for how to color bold and underlined text automatically.
• Color Themes - Extensive list of terminal color themes by Phraktured.
• Xcolors by dkeg (see files with paths matching theme/dkeg - theme in the repository)
• base16 color schemes

Display the 256 colors

Prints the 256 colors across the screen.

$ (x=`tput op` y=`printf %76s`;for i in {0..256};do o=00$i;echo -e ${o:${#o}-3:3} `tput setaf $i;tput setab $i`${y// /=}$x;done)

Display tput escape codes

Replace tput op with whatever tput you want to trace. op is the default foreground and background color.

$ ( strace -s5000 -e write tput op 2>&2 2>&1 ) | tee -a /dev/stderr | grep -o '"[^"]*"'

033[\033[1;34m"\33[39;49m"\033[00m

Enumerate supported colors

The following command will let you discover all the terminals you have terminfo support for, and the number of colors each terminal supports. The possible values are: 8, 15, 16, 52, 64, 88 and 256.

$ for T in `find /usr/share/terminfo -type f -printf '%f '`;do echo "$T `tput -T $T colors`";done|sort -nk2

Eterm-88color 88
rxvt-88color 88
xterm+88color 88
xterm-88color 88
Eterm-256color 256
gnome-256color 256
konsole-256color 256
putty-256color 256
rxvt-256color 256
screen-256color 256
screen-256color-bce 256
screen-256color-bce-s 256
screen-256color-s 256
xterm+256color 256
xterm-256color 256

Enumerate terminal capabilities

This command is useful to see what features that are supported by your terminal.

$ infocmp -1 | tr -d '\0\t,' | cut -f1 -d'=' | grep -v "$TERM" | sort | column -c80

acsc		ed		kcuu1		kich1		rmso
am		el		kDC		kLFT		rmul
bce		el1		kdch1		km		rs1
bel		enacs		kel		kmous		rs2
blink		eo		kend		knp		s0ds
bold		flash		kEND		kNXT		s1ds
btns#5		fsl		kent		kpp		s2ds
bw		home		kf1		kPRV		s3ds
ccc		hpa		kf10		kRIT		sc
civis		hs		kf11		kslt		setab
clear		ht		kf12		lines#24	setaf
cnorm		hts		kf13		lm#0		setb
colors#0x100	ich		kf14		mc0		setf
cols#80		ich1		kf15		mc4		sgr
cr		il		kf16		mc5		sgr0
csr		il1		kf17		mc5i		sitm
cub		ind		kf18		mir		smacs
cub1		indn		kf19		msgr		smam
cud		initc		kf2		ncv#0		smcup
cud1		is1		kf20		npc		smir
cuf		is2		kf3		op		smkx
cuf1		it#8		kf4		pairs#0x7fff	smso
cup		ka1		kf5		rc		smul
cuu		ka3		kf6		rev		tbc
cuu1		kb2		kf7		ri		tsl
cvvis		kbs		kf8		rin		u6
dch		kc1		kf9		ritm		u7
dch1		kc3		kfnd		rmacs		u8
dl		kcbt		kFND		rmam		u9
dl1		kcub1		kHOM		rmcup		vpa
dsl		kcud1		khome		rmir		xenl
ech		kcuf1		kIC		rmkx		xon

Color scheme scripts

See [3] for scripts which display a chart of your current terminal scheme.

True color support

Some terminals support the full range of 16 million colors (RGB, each with 8 bit resolution): xterm, konsole, st, etc. The corresponding TERM values xterm-direct, konsole-direct, st-direct, etc. are supported starting with ncurses version 6.1 [4]. For more info about terminal emulators and applications that support true color, see [5].

Note that the Linux kernel supports the SGR (Select Graphic Rendition) escape sequences for true-color, but it is pointless to use it, because the driver maps the 24-bit color specifications to a 256-colors color map in the kernel (see the functions rgb_foreground, rgb_background). For this reason, there is no terminfo entry linux-direct.

See also

• lolcat clone in x64 assembly