I am running some unit test code. The unit test code outputs regular text. There is a lot of the text so I want to highlight for the user important keywords.

In this case the keywords are "PASS" and "FAIL".

How do you colorize "PASS" to be green and "FAIL" to be red?

  • Have you thought about supressing stdout/stderr of tests that pass, and only printing stdout/stderr for failed tests? PHPUnit does this, or is configurable to do this. I've found that this approach works quite well, YMMV. Commented Aug 30, 2012 at 2:44

5 Answers 5


supercat seems to do what you're looking for.

Package: supercat
Description-en: program that colorizes text for terminals and HTML
 Supercat is a program that colorizes text based on matching regular
 expressions/strings/characters. Supercat supports html output as well
 as standard ASCII text. Unlike some text-colorizing programs that
 exist, Supercat does not require you to have to be a programmer to
 make colorization rules.
Homepage: http://supercat.nosredna.net/

There doesn't seem to be any way to tell it what to colourise on the command line, you have to specify a config file.

I seem to recall there used to be a program called 'hilite' or 'hl' that highlighted text that matched a pattern (like grep --colour, but displaying non-matching lines too), but I couldn't find it when I searched for it.

Finally, GNU grep can be used to highlight patterns - but only one colour can be used (i.e. you can't have PASS in green and FAIL in red, both would be highlighted with the same colour).

Pipe your data through something like this:

grep -E --color "\b(PASS|FAIL)\b|$"

This example uses grep's -E extended regexp option, but -G basic regexp, -F fixed-string, and -P PCRE can also be made to work.

All matches will be highlighted. Default is red, or set the GREP_COLOR env var.

The key to this working is that the final |$ in the pattern matches end-of-line (i.e. all lines match) so all lines will be displayed (but not colorised).

The \b are word-boundary markers so that it matches e.g. FAIL but not FAILURE. they're not necessary, so remove them if you want to match partial words.

Here's the example wrapper script for supercat that I wrote yesterday. It works, but in writing it, I discovered that supercat doesn't have any option for case-insensitive searches. IMO, that makes the program significantly less useful. It did, however, greatly simplify the script because I didn't have to write a '-i' option :)

#! /bin/bash 

# Requires: tempfile from debian-utils, getopt from util-linux, and supercat

SCRIPTNAME=$(basename $0)
CFGFILE=$(tempfile -p spc)

usage() {
  cat <<__EOF__
Highlight regexp patterns found on stdin or files specified on command
line with specified colours.

Usage: $SCRIPTNAME [ --colour "pattern" ...] [FILE]


        -k,--black   regexp
        -r,--red     regexp
        -g,--green   regexp
        -y,--yellow  regexp
        -b,--blue    regexp
        -m,--magenta regexp
        -c,--cyan    regexp
        -w,--white   regexp


    run-script.sh | $SCRIPTNAME --green PASS --red FAIL

  exit 0

# Format definition from the spc man page:
#HTML Color Name      Col A N T RE / String / Characters
FMT="%-20s %3s %1s %1s %1s (%s)\n"

add_color_to_config() {

  printf "$FMT" "$COLOR" "$COLOR" - 0 r "$PATTERN" >> "$CFGFILE"

# uses the "getopt" program from util-linux, which supports long
# options. The "getopts" built-in to bash does not.
TEMP=$(getopt \
       -o 'hk:r:g:y:b:m:c:w:' \
       -l 'help,black:,red:,green:,yellow:,blue:,magenta:,cyan:,white:' \
       -n "$0" -- "$@")

if [ $? != 0 ] ; then echo "Terminating..." >&2 ; exit 1 ; fi

eval set -- "$TEMP"

while true ; do
    case "$1" in
        -k|--bla*)       add_color_to_config blk "$2" ; shift 2 ;;
        -r|--red)        add_color_to_config red "$2" ; shift 2 ;;
        -g|--gre*)       add_color_to_config grn "$2" ; shift 2 ;;
        -y|--yel*)       add_color_to_config yel "$2" ; shift 2 ;;
        -b|--blu*)       add_color_to_config blu "$2" ; shift 2 ;;
        -m|--mag*)       add_color_to_config mag "$2" ; shift 2 ;;
        -c|--cya*)       add_color_to_config cya "$2" ; shift 2 ;;
        -w|--whi*)       add_color_to_config whi "$2" ; shift 2 ;;

        -h|--hel*)       usage ; exit 0 ;;

        --)         shift ; break ;;

        *)          echo 'Unknown option!' ; exit 1 ;;

spc -R -c "$CFGFILE" "$@"
rm -f "$CFGFILE"
  • 1
    BTW, if you used supercat you could modify the script you posted to generate a temporary config file based on the command-line args, and then call spc -c /path/to/your/temp/config. This would allow you to easily specify different colours for different patterns on the command line.
    – cas
    Commented Aug 28, 2012 at 23:07
  • also btw, i wrote a simple wrapper script to do that. i have to head in to work now but i'll clean it up, add some comments, etc and post it later today.
    – cas
    Commented Aug 29, 2012 at 0:05
  • +1 for the egrep solution, simple, just works!
    – Michahell
    Commented Dec 21, 2022 at 8:10
  • 1
    @Michahell egrep is obsolete. should use grep -E. I'll fix that.
    – cas
    Commented Dec 21, 2022 at 9:30

Here is a general-purpose script to colorize regex patterns (probably needs some retouching):

#! /bin/bash

color_to_num () {
  case $1 in
    black)  echo 0;;
    red)    echo 1;;
    green)  echo 2;;
    yellow) echo 3;;
    blue)   echo 4;;
    purple) echo 5;;
    cyan)   echo 6;;
    white)  echo 7;;
    *)      echo 0;;

# default values for foreground and background colors
bold="$(tput bold)"

while getopts f:b:sli option; do
  case "$option" in
    f) fg="$OPTARG";;
    b) bg="$OPTARG";;
    s) bold="";;
    l) boundary=".*";;
    i) italics="$(tput sitm)";;

shift $(($OPTIND - 1))


if [ -n "$fg" ]; then
  fg=$(tput setaf $(color_to_num $fg))
if [ -n "$bg" ]; then
  bg=$(tput setab $(color_to_num $bg))

if [ -z "$fg$bg" ]; then
  fg=$(tput smso)

sed "s/${boundary}${pattern}${boundary}/${bold}${italics}${fg}${bg}&$(tput sgr0)/g"

Name it hilite.sh and use it this way:

$ ./BIN_PROGRAM | hilite.sh -f green PASS | hilite.sh -f red FAIL

$ # Here is an example one liner
$ echo -e "line 1: PASS\nline 2: FAIL" | hilite.sh -f green PASS | hilite.sh -f red FAIL
  • I made this community wiki because my solution doesn't work. Commented Aug 28, 2012 at 21:45
  • An easy way to test is to make another script that echos text with the keywords "PASS" and "FAIL". That would then be called by this script. Commented Aug 28, 2012 at 21:46
  • Slightly off topic, but I have to point out that parsing the output of $BIN via eval into command substitution is probably fragile, cumbersome, and downright dangerous. STDOUT is a stream and is generally meant to be processed by stream like tools. Trying to capture an entire stream in a variable is not very efficient. Also, eval is dangerously powerful, so only use it if you really know what you are doing.
    – jw013
    Commented Aug 28, 2012 at 22:15
  • I replaced the script with a working one.
    – angus
    Commented Aug 28, 2012 at 22:30
  • @angus, really really good and impressive script IMO. Commented Aug 29, 2012 at 13:25

Embedding arbitrary strings (like tput output) into sed replace expressions is problematic because you have to ensure (by escaping) the string is valid sed syntax, which is more complexity that is best avoided. I would use awk instead. Just as an example:

{ echo line 1: PASS; echo line 2: FAIL; } | 
    awk -v "red=$(tput setaf 1)" -v "green=$(tput setaf 2)" \
        -v "reset=$(tput sgr0)" '
    { for (i = 1; i <= NF; i++) {
           if ($i == "FAIL") printf "%s", red "FAIL" reset;
           else if ($i == "PASS") printf "%s", green "PASS" reset;
           else printf "%s", $i

           if (i == NF) printf "%s", ORS
           else printf "%s", OFS 

The key is to assign the tput sequences to awk variables, done here using the -v options.

  • I ran your program and it does what is needed. Huzzah! But unfortunately I am not an awk guru so I find it hard to understand what is going on. Correct me where I am wrong. For each new line awk is run? The for loop in the awk source code is doing: "for all tokens in the line"? then it processes each token? Commented Aug 29, 2012 at 13:16
  • Awk thinks in terms of fields and records. By default, records are lines of text and fields are non-whitespace. An awk script consists of a set of blocks (the stuff between the {} at the top level). Each block is associated with a condition - in my post above there is none because I want to unconditionally act on every input line. Awk operates by reading records from files or standard input (in this case it is STDIN b/c no file names were provided), and matching them against every block in order, executing the block on the record if the condition matches.
    – jw013
    Commented Aug 29, 2012 at 13:51

use printf:

printf "\e[%sm%s\e[00m\n" <some_number> <text_in_colour>


printf "\e[%sm%s\e[00m\n" 32 yodle

the last \n adds the newline character.

to see possible values of try something like:

for i in {0..9} {30..38} {90..98} {100..108};
    printf "%d:\e[%sm%s\e[00m\n" $i "$i" yodle;

besides colour you can add modifiers like bold or underline or coloured text with coloured background by combining the numbers. To create blue text with grey background that is underlined and striked through use:

printf "\e[%sm%s\e[00m\n" "4;9;34;107" yodle




If you're happy to install a BASH script and ack, the hhlighter package has useful default colours and an easy interface https://github.com/paoloantinori/hhighlighter:

hhighlight example

You can use it like so to highlight rows that start with FAIL:

h -i 'FAIL.*'

or that contain FAIL:

h -i '.*FAIL.*'

or for various common log entries:

h -i '.*FAIL.*' '.*PASS.*' '.*WARN.*'

And of course, for a single colour (red) with plain grep:

$ printf 'Pass: good job\nFail: bad job\n' | grep -Ei --colour=auto '^|fail.*'

The ^ matches every line, but is a special matcher and prints the entire line. The the expression to be highlighted is defined after a |. Further expressions can be added as long as they're separated with |.

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