Colorized grep — viewing the entire file with highlighted matches

Question

I find grep\'s --color=always flag to be tremendously useful. However, grep only prints lines with matches (unless you ask for context lines). Give

Answer 1

You can use my highlight script from https://github.com/kepkin/dev-shell-essentials

It's better than grep because you can highlight each match with its own color.

$ command_here | highlight green "input" | highlight red "output"

Answer 2

If you want highlight several patterns with different colors see this bash script.

Basic usage:

echo warn error debug info 10 nil | colog

You can change patterns and colors while running pressing one key and then enter key.

Answer 3

As grep -E '|pattern' has already been suggested, just wanted to clarify it's possible to highlight the whole line too.

For example tail -f /somelog | grep --color -E '| \[2].*':

Answer 4

I use rcg from "Linux Server Hacks", O'Reilly. It's perfect for what you want and can highlight multiple expressions each with different colours.

#!/usr/bin/perl -w
#
#       regexp coloured glasses - from Linux Server Hacks from O'Reilly
#
#       eg .rcg "fatal" "BOLD . YELLOW . ON_WHITE"  /var/adm/messages
#
use strict;
use Term::ANSIColor qw(:constants);

my %target = ( );

while (my $arg = shift) {
        my $clr = shift;

        if (($arg =~ /^-/) | !$clr) {
                print "Usage: rcg [regex] [color] [regex] [color] ...\n";
                exit(2);
        }

        #
        # Ugly, lazy, pathetic hack here. [Unquote]
        #
        $target{$arg} = eval($clr);

}

my $rst = RESET;

while(<>) {
        foreach my $x (keys(%target)) {
                s/($x)/$target{$x}$1$rst/g;
        }
        print
}

Answer 5

Here's my approach, inspired by @kepkin's solution:

# Adds ANSI colors to matched terms, similar to grep --color but without
# filtering unmatched lines. Example:
#   noisy_command | highlight ERROR INFO
#
# Each argument is passed into sed as a matching pattern and matches are
# colored. Multiple arguments will use separate colors.
#
# Inspired by https://stackoverflow.com/a/25357856
highlight() {
  # color cycles from 0-5, (shifted 31-36), i.e. r,g,y,b,m,c
  local color=0 patterns=()
  for term in "$@"; do
    patterns+=("$(printf 's|%s|\e[%sm\\0\e[0m|g' "${term//|/\\|}" "$(( color+31 ))")")
    color=$(( (color+1) % 6 ))
  done
  sed -f <(printf '%s\n' "${patterns[@]}")
}

This accepts multiple arguments (but doesn't let you customize the colors). Example:

$ noisy_command | highlight ERROR WARN

Answer 6

another dirty way:

grep -A80 -B80 --color FIND_THIS IN_FILE

I did an

alias grepa='grep -A80 -B80 --color'

in bashrc.