How to colorize diff on the command line?

Question

When I have a diff, how can I colorize it so that it looks good? I want it for the command line, so please no GUI solutions.

Answer 1

Man pages for diff suggest no solution for colorization from within itself. Please consider using colordiff. It's a wrapper around diff that produces the same output as diff, except that it augments the output using colored syntax highlighting to increase readability:

diff old new | colordiff

or just:

colordiff old new

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Installation:

• Ubuntu/Debian: sudo apt-get install colordiff
• OS X: brew install colordiff or port install colordiff

Answer 2

I use grc (Generic Colouriser), which allows you to colour the output of a number of commands including diff.

It is a python script which can be wrapped around any command. So instead of invoking diff file1 file2, you would invoke grc diff file1 file2 to see colourised output. I have aliased diff to grc diff to make it easier.

Answer 3

diff --color option was added to GNU diffutils 3.4 (2016-08-08)

This is the default diff implementation on most distros, which will soon be getting it.

Ubuntu 18.04 has diffutils 3.6 and therefore has it.

On 3.5 it looks like this:

Tested:

diff --color -u \
  <(seq 6 | sed 's/$/ a/') \
  <(seq 8 | grep -Ev '^(2|3)$' | sed 's/$/ a/')

Apparently added in commit c0fa19fe92da71404f809aafb5f51cfd99b1bee2 (Mar 2015).

I have also requested word level diff as from diff-highlight at: https://lists.gnu.org/archive/html/diffutils-devel/2017-01/msg00001.html

Answer 4

Coloured, word-level diff ouput

Here's what you can do with the the below script and diff-highlight:

#!/bin/sh -eu

# Use diff-highlight to show word-level differences

diff -U3 --minimal "$@" |
  sed 's/^-/\x1b[1;31m-/;s/^+/\x1b[1;32m+/;s/^@/\x1b[1;34m@/;s/$/\x1b[0m/' |
  diff-highlight

_{(Credit to @retracile's answer for the sed highlighting)}

Answer 5

And for those occasions when a yum install colordiff or an apt-get install colordiff is not an option due to some insane constraint beyond your immediate control, or you're just feeling crazy, you can re-invent the wheel with a line of sed:

sed 's/^-/\x1b[41m-/;s/^+/\x1b[42m+/;s/^@/\x1b[34m@/;s/$/\x1b[0m/'

Throw that in a shell script and pipe unified diff output through it.

It makes hunk markers blue and highlights new/old filenames and added/removed lines in green and red background, respectively.¹ And it will make trailing space² changes more readily apparent than colordiff can.

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¹ Incidentally, the reason for highlighting the filenames the same as the modified lines is that to correctly differentiate between the filenames and the modified lines requires properly parsing the diff format, which is not something to tackle with a regex. Highlighting them the same works "well enough" visually and makes the problem trivial. That said, there are some interesting subtleties.

² But not trailing tabs. Apparently tabs don't get their background set, at least in my xterm. It does make tab vs space changes stand out a bit though.

Answer 6

Use Vim:

diff /path/to/a /path/to/b | vim -R -

Or better still, VimDiff (or vim -d, which is shorter to type) will show differences between two, three or four files side-by-side.

Examples:

vim -d /path/to/[ab]

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vimdiff file1 file2 file3 file4