Colored word-diff just like git’s

colordiffcolorsdiff()git

I've been for long using git's (colored) --word-diff which I find awesome. I found myself today in a situation where I had two strings I needed to compare word by word and craving for something just like git's diff.

I am aware of wdiff + colordiff, but its results certainly aren't stellar:

me@me:~$ wdiff <(echo -e "abc\ndef") <(echo -e "dbcx\ndef") | colordiff
[-abc-]{+dbcx+}
def

Is there any better option around? I don't particularly like those [-, -] and {+, +}.

Best Answer

You can use git's own diff-highlight. It can highlight word differences in unified diff output, and it can also cope with ANSI colors on input. So you can do something like this:

colordiff -u <(echo -e "foo abc\ndef") <(echo -e "foo dbcx\ndef") | diff-highlight

Related Solutions

How to pipe colored diff output to less

diff cannot output colors, you need another program, such as colordiff for that. Colors in the terminal are printed via ANSI escape codes which less does not interpret by default. To get less to correctly show colors, you need the -r, or even better, -R switch:

colordiff -- "$file1" "$file2" | less -R

From man less:

   -R or --RAW-CONTROL-CHARS
          Like -r, but only ANSI  "color"  escape  sequences  are
          output in "raw" form.  Unlike -r, the screen appearance
          is maintained correctly in most  cases.   ANSI  "color"
          escape sequences are sequences of the form:

               ESC [ ... m

          where  the  "..."  is  zero or more color specification
          characters For the purpose of keeping track  of  screen
          appearance,  ANSI color escape sequences are assumed to
          not move the cursor.  You  can  make  less  think  that
          characters  other  than  "m"  can end ANSI color escape
          sequences by setting the environment  variable  LESSAN‐
          SIENDCHARS  to  the  list of characters which can end a
          color escape sequence.  And you  can  make  less  think
          that characters other than the standard ones may appear
          between the ESC and the m by  setting  the  environment
          variable  LESSANSIMIDCHARS  to  the  list of characters
          which can appear.

Alternatively, you can use more which will display colors correctly by default.

If you cannot install external programs, you should be able to get the same output using a more manual approach:

diff a b | 
   perl -lpe 'if(/^</){$_ = "\e[1;31m$_\e[0m"} 
              elsif(/^>/){$_ = "\e[1;34m$_\e[0m"}'

Getting diff (or git diff) to show inserted hunks properly

Git 2.9 was released earlier this year which included the experimental flag --compaction-heuristic on the git diff command:

In 2.9, Git's diff engine learned a new heuristic: it tries to keep hunk boundaries at blank lines, shifting the hunk "up" whenever the bottom of the hunk matches the bottom of the preceding context, until we hit a blank line.

I don't think GitHub has it enabled for diffs on the web UI for Pull Requests and comparisons, but you can do it locally. I'd recommend using it in conjunction with --word-diff if you need that level of granularity.

More details available on the GitHub blog: https://github.com/blog/2188-git-2-9-has-been-released

Best Answer

Related Solutions

How to pipe colored diff output to less

Getting diff (or git diff) to show inserted hunks properly

Related Question