278

I use the --colour option of grep a lot, but I often use less as well. How can I pipe grep results to less and still preserve the coloring. (Or is that possible?)

grep "search-string" -R * --colour | less 

EDIT:

I'm looking for a direct solution or anything equivalent to this.

3
  • possible duplicate of Get colors in 'less'' command Sep 19, 2014 at 8:07
  • What does * do? From the man page of grep: *: The preceding item will be matched zero or more times. But I still don't understand..! @JeremyPowell
    – Shayan
    Sep 1, 2019 at 17:37
  • 1
    @Shayan, the '*' in this case is for the file arguments. It gets processed by the shell which expands it to all files in the directory. The search string is enclosed in double quotes in the example.
    – NeilG
    Nov 2, 2019 at 4:15

5 Answers 5

317

When you simply run grep --color it implies grep --color=auto which detects whether the output is a terminal and if so enables colors. However, when it detects a pipe it disables coloring. The following command:

grep --color=always -R "search string" * | less

Will always enable coloring and override the automatic detection, and you will get the color highlighting in less.

EDIT: Although using just less works for me, perhaps older version require the -R flag to handle colors, as therefromhere suggested.

14
  • 165
    You need to use less -R for the colour encoding to be interpreted by less correctly Sep 4, 2009 at 23:24
  • 1
    It worked for me with just less, it may be version dependent.
    – drrlvn
    Sep 5, 2009 at 12:14
  • 2
    A (hopefully) useful addendum: I needed to exclude some matches but maintain the colouring, so I actually ended up with grep pattern file | grep -v badpattern | grep --colour=always pattern | less -R, which met my needs perfectly. (Thanks again!) Mar 6, 2012 at 15:35
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    I can't believe they just implemented the color-handling feature in less and therefore missed the chance to have a special colorless tool. For the name alone it should have been done! I should probably write a patch that invokes -R automatically when the binary is run as colorless.
    – Christian
    Jul 10, 2013 at 0:42
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    @OwenBlacker It might not be an alias. You might have $LESS set with -R.
    – greyfade
    Aug 30, 2016 at 21:01
33

You can put this in your .bashrc file:

export GREP_OPTIONS="--color=always"

or create an alias like this:

alias grepc="grep --color=always"

and you will need to use the -R option for less, as pointed out by therefromhere

3
  • 36
    Warning!: GREP_OPTIONS="--color=always" may break many scripts that use grep (or (e|f)grep).
    – mctylr
    Mar 12, 2010 at 19:25
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    Yeah, better to just alias grep. You can always get pure grep with GREP, or override the --color option manually.
    – asmeurer
    Jul 18, 2011 at 22:51
  • This doesn't work for me, alias does work though.
    – saeedgnu
    Feb 28, 2014 at 3:30
12

In case like this, I prefer to actually create small sh files and put them on /usr/local/bin.
I usually use grep in the recursive way on the pwd, so thats my personal script:

#!/bin/sh
grep --color=always -r "$@" . | less -R

And then I've just copied it as /usr/local/bin/g (yes, I use it a lot)

2
  • 3
    Why not just use shell functions for this kind of thing? g() { grep --color=always -r "$@" . | less -R } works identically and probably will give (minutely) better performance.
    – 00dani
    Jan 11, 2017 at 2:00
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    @00dani yeah, that's a valid alternative too and sometimes I use it. Please note that in this case, most time is spent in IO and therefore there is no perceivable performance boost :) Another difference is that once in your PATH, this script can be used with other shell scripts and aliases too; the function instead needs to be explicitly loaded
    – Iazel
    Jan 27, 2019 at 12:15
1

Don't alias "grep", better to alias "less" which is never used by shells. In your .bashrc just put: alias less="less -r".

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    Not quite right. One needs to use both grep --color=always and less -R. Note that grep only knows it is being piped into some other process and the --color=auto option uses solely this information to decide if will output colors or not.
    – brandizzi
    Apr 17, 2013 at 18:35
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    Note that less option -r is different than -R. Probably -R is safer. Jan 9, 2014 at 0:26
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    So why down-vote my solution. The OP specifically ask for less with the example already using `--color' option.
    – not2qubit
    Jan 9, 2014 at 15:58
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    An alias is probably undesirable here. less supports a $LESS environment variable. So, instead of an alias, export LESS='-R' might be preferable.
    – greyfade
    Aug 30, 2016 at 20:59
0

I need to run

grep --color=always -R "search string" * | less - r

with the -r flag after less, in order this to run.

2
  • What does * do? From the man page of grep: *: The preceding item will be matched zero or more times. But I still don't understand..!
    – Shayan
    Sep 1, 2019 at 17:36
  • 1
    @Shayan It will search for the text "search string" in all files.
    – Pepedou
    Jun 1, 2020 at 19:41

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