11

I can do the following to see if some word is available in the output of "cat":

cat filename | grep word

This filters the output and shows only those lines which contain "word". Now, is it possible to only highlight the "word" in the output, without dropping other lines?

  • 2
    grep word filename is clearer and faster. ;) Also, less can do this while also providing paging. Just search for word by typing /word (the term is actually a regular expression, just like grep) – Alexios Dec 25 '13 at 15:50
16

You can grep for an EOL along with your real query (if you already have an alias for grep to use --color, as is default in many distributions, you can omit it in the following examples):

grep --color=auto 'word\|$' file

Since the EOL is not a real character, it won't highlight anything, but it will match all lines.

If you would prefer not to have to escape the pipe character, you can use extended regular expressions:

grep -E --color=auto 'word|$' file
  • Thank you. The highlighted word is currently red on my computer. Is it possible to customize the color as well? – Meysam Dec 25 '13 at 6:20
  • 1
    @Meysam You can do so using the GREP_COLOR(S) environment variable. gnu.org/software/grep/manual/html_node/… – Chris Down Dec 25 '13 at 6:24
5

If you haven't GNU grep available, here is something more portable:

grepc()
{
  pattern=$1
  shift
  esc=$(printf "\033")
  sed 's"'"$pattern"'"'$esc'[32m&'$esc'[0m"g' "$@"
}

You can customize the color using one of these codes

30m black
31m red
32m green
33m yellow
34m blue
35m magenta
36m cyan
37m white

Using 7m instead of a color code will put the string in reverse video.

  • 1
    Have you tested it? This is what I see in the output: ^[[32mword^[[0m – Meysam Dec 25 '13 at 7:15
  • @Meysam Sorry, ^[ is how the escape character is represented at least under vi, answer updated to avoid the ambiguity. – jlliagre Dec 25 '13 at 9:19
  • Question closed, so here is a one-liner solution: cat testt.c | sed $'s/main/\E[31m&\E[0m/g' Hope it helps – Dr Beco Nov 20 '17 at 5:09

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