Getting colored results when using a pipe from grep to less

colors grep pipe less

79,078

Solution 1

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.

Solution 2

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

Solution 3

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)

Solution 4

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

View more solutions

79,078

Jeremy Powell

Updated on September 17, 2022

Comments

Jeremy Powell over 1 year
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.
- Ciro Santilli Путлер Капут 六四事 over 9 years
  
  possible duplicate of Get colors in 'less'' command
- Shayan almost 5 years
  
  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
- NeilG over 4 years
  
  @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.
pion over 14 years

You need to use less -R for the colour encoding to be interpreted by less correctly
Drona over 14 years

It worked for me with just less, it may be version dependent.
Jeremy Powell over 14 years

wow. I thought 'auto' only depended on the terminal type. I may be jumping the gun, but this may revolutionize the way I use linux :P
mctylr about 14 years

Warning!: GREP_OPTIONS="--color=always" may break many scripts that use grep (or (e|f)grep).
asmeurer almost 13 years

Yeah, better to just alias grep. You can always get pure grep with GREP, or override the --color option manually.
Owen Blacker about 12 years

Awesome. Though I too to use less -R to get less to display colours, rather than the colouring escape codes :o)
Owen Blacker about 12 years

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!)
brandizzi about 11 years

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.
David Winiecki over 10 years

Yay, works for git log -p too. :)
Craig McQueen over 10 years

Note that less option -r is different than -R. Probably -R is safer.
not2qubit over 10 years

So why down-vote my solution. The OP specifically ask for less with the example already using `--color' option.
saeedgnu over 10 years

This doesn't work for me, alias does work though.
Ray Foss over 9 years

Using grep without -R and more instead of less -R works for me... and its shorter. In other words, this works on Fedora 20 grep --color=always -Irn "foo_bar" | more
cfi over 8 years

@spatz: You could integrate Dennis answer into yours to make it a one-stop-shop. Integration answers are perfectly wanted on SO. Thanks! That would solve the problem Owen addressed in his comment.
greyfade almost 8 years

An alias is probably undesirable here. less supports a $LESS environment variable. So, instead of an alias, export LESS='-R' might be preferable.
greyfade almost 8 years

@OwenBlacker It might not be an alias. You might have $LESS set with -R.
00dani over 7 years

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.
Ligemer about 6 years

Ubuntu 16.04 cat file.log | grep --color=always password | less -R
Rory O'Kane about 6 years

To make less default to always pass through colors, edit your LESS environment variable to include -R or its long form --RAW-CONTROL-CHARS. The LESS variable contains a space-separated list of default flags for less.
Iazel over 5 years

@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
Shayan almost 5 years

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..!
Pepedou about 4 years

@Shayan It will search for the text "search string" in all files.
Sujay Phadke over 3 years

old Q and answer, but thank you! works like a charm.