Color regex matches - without dropping misses

Question

When using grep --color=always I can get pretty color highlighting for regex matches.

However, grep only returns lines with at least one match.

Answer 1

The simplest solution would be to use egrep --color=always 'text|^' which would match all line beginnings but only color the desired text.

Answer 2

Here is a script I use to colorize output.

I think I found the idea/snippet on some kind of blog or bash/sed tutorial - can't find it anymore, it was very long time ago.

#!/bin/bash

red=$(tput bold;tput setaf 1)            
green=$(tput setaf 2)                    
yellow=$(tput bold;tput setaf 3)         
fawn=$(tput setaf 3)
blue=$(tput bold;tput setaf 4)           
purple=$(tput setaf 5)
pink=$(tput bold;tput setaf 5)           
cyan=$(tput bold;tput setaf 6)           
gray=$(tput setaf 7)                     
white=$(tput bold;tput setaf 7)          
normal=$(tput sgr0)                      

sep=`echo -e '\001'` # use \001 as a separator instead of '/'

while [ -n "$1" ] ; do
  color=${!1}
  pattern="$2"
  shift 2

  rules="$rules;s$sep\($pattern\)$sep$color\1$normal${sep}g"
done

#stdbuf -o0 -i0 sed -u -e "$rules"
sed -u -e "$rules"

Usage:

./colorize.sh color1 pattern1 color2 pattern2 ...

e.g.

dmesg | colorize.sh red '.*Hardware Error.*' red 'CPU[0-9]*: Core temperature above threshold' \
green 'wlan.: authenticated.*' yellow 'wlan.: deauthenticated.*'

Doesn't work well with overlapping patterns, but I've found it very useful anyway.

HTH

Answer 3

This little function works well in my ZShell:

function color_grep {
    sed s/$1/$fg[yellow]$1$terminfo[sgr0]/g
}

(Needs

autoload colors zsh/terminfo

)

Maybe you can do something similar?

Edit: Sorry, this won't work with regexes. You will have to tweak it a bit ...

Answer 4

I'm digging this little python utility. If not on debian, use alien to convert to rpm.

http://korpus.juls.savba.sk/~garabik/software/grc.html

regexp=.*red
colours="\033[38;5;160m"
count=once

This is a nice page on terminal colors.

http://www.pixelbeat.org/docs/terminal_colours/

(Queen's english is so colourful.)

Answer 5

You could use the -C<num> option to grep which shows you <num> lines of context around your match. Just make sure <num> is as least as large as the number of lines in your file.

Answer 6

I recently made something similar as a filter. I use it to color the "headers" in a tail with multiple files, like this:

tail -f access.log error.log foo.log | logcol.sh

The headers look like this:

==> access.log <==

I got confused by the quick changes between the different logfiles, so this logcol.sh helps. The ==> is hardcoded for the specific usage but could be a parameter as well.

#!/bin/sh
while read line
do
  if test `expr "$line" : "==>.*"`  -eq 0 ;
  then
    printf '\033[0m%s\n' "$line"
  else
    printf '\033[0;31m%s\n' "$line"
  fi
done

Maybe not the most elegant but I think it's quite readable. I hope I don't have any typos ;-) HTH, rob