#!/usr/bin/env bash

# @(#) s1       Demonstrate colorization of text.

# Utility functions: print-as-echo, print-line-with-visual-space, debug.
# export PATH="/usr/local/bin:/usr/bin:/bin"
LC_ALL=C ; LANG=C ; export LC_ALL LANG
pe() { for _i;do printf "%s" "$_i";done; printf "\n"; }
pl() { pe;pe "-----" ;pe "$*"; }
em() { pe "$*" >&2 ; }
db() { ( printf " db, ";for _i;do printf "%s" "$_i";done;printf "\n" ) >&2 ; }
db() { : ; }
C=$HOME/bin/context && [ -f $C ] && $C my-hilite

pl " Results, file missing:"
FILE=test1
rm -f $FILE
if [ -f "$FILE" ];
then
  echo "File $FILE does exist." |
  my-hilite -f green
else
  echo "File $FILE does NOT exist." |
  my-hilite -f red
fi

touch $FILE
pl " Results, file present:"
if [ -f "$FILE" ];
then
  echo "File $FILE does exist." |
  my-hilite -f green
else
  echo "File $FILE does NOT exist." |
  my-hilite -f red
fi

pl " Results, if only string \"File\" should be colored:"
echo " The File is unimportant, the contents are what matters." |
my-hilite -f blue "File"

exit 0

./s1 | ansifilter -B

Environment: LC_ALL = C, LANG = C
(Versions displayed with local utility "version")
OS, ker|rel, machine: Linux, 3.16.0-7-amd64, x86_64
Distribution        : Debian 8.11 (jessie) 
bash GNU bash 4.3.30
my-hilite - ( local: RepRev 1.2, ~/bin/my-hilite, 2019-04-11 )

-----
 Results, file missing:
File test1 does NOT exist.

-----
 Results, file present:
File test1 does exist.

-----
 Results, if only string "File" should be colored:
 The File is unimportant, the contents are what matters.

#!/usr/bin/env bash

# @(#) my-hilite        Colorize regex pattern matches, insert tput codes with sed.
# $Id: my-hilite,v 1.2 2019/04/11 15:12:31 drl Exp $

# Home:
# http://unix.stackexchange.com/questions/46562/how-do-you-colorize-only-some-keywords-for-a-bash-script

# Utility functions: print-as-echo, print-line-with-visual-space, debug.
LC_ALL=C ; LANG=C ; export LC_ALL LANG
pe() { for _i;do printf "%s" "$_i";done; printf "\n"; }
pl() { pe;pe "-----" ;pe "$*"; }
em() { pe "$*" >&2 ; }
db() { ( printf " db, ";for _i;do printf "%s" "$_i";done;printf "\n" ) >&2 ; }
db() { : ; }

# Short circuit for debug -- MUST BE FIRST ARGUMENT.
if [[ $# -gt 0 && "$1" =~ ^-de*b*u*g* ]]
then
  db() { ( printf " db, ";for _i;do printf "%s" "$_i";done;printf "\n" ) >&2 ; }
  shift;
else
  db() { : ; }
fi

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;;
  esac
}

# default values for foreground and background colors
bg=
fg=
bold="$(tput bold)"
italics=""
boundary=""

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

shift $(($OPTIND - 1))

if [ $# -le 0 ]
then
  pattern="^.*$"
else
  pattern="$*"
fi

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

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

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

exit