I diff a lot of text files while I’m working and for the most part I’m usually comparing files under version control, but that’s not always the case. Reading diffs in a format I’m used to makes things considerably easier to understand, so I need a simple way to generate unified diffs with colour between arbitrary files.
tldr; use Git to diff everything with git diff --no-index <path> <path>.
Oldschool
For the longest time I used, but was unimpressed with, the basic diff command.
If I wanted to get the difference between two files I would execute diff <path>
<path>. This outputs “Context Format” diffs which look something like this:
1,2c1,4
< First Line
< Second Line
---
> New First Line
>
>
> Forth Line
While this does convey the necessary information I find it much less intuitive when compared to the “Unified Format”, which most other tools I use output by default:
--- a.txt 2017-03-04 13:25:53.000000000 -0500
+++ b.txt 2017-03-04 13:26:37.000000000 -0500
@@ -1,2 +1,4 @@
-First Line
-Second Line
+New First Line
+
+
+Forth Line
Eventually I decided to RTFM and found I could generate unified diffs by
passing the -u or --unified flag to diff.
Something’s Missing
Unified diffs are a huge step up from context diffs but output from diff lacks
any colour, something I find helps tremendously with readability. Searching the
internet for a way to colourize the output of diff led to me
colordiff. While this works nicely it doesn’t seem
to come installed by default on systems I use.
I can however, pretty much guarantee Git will be installed on any random machine I need to access.
Just Use Git
Git has a handy feature that allows you to use git diff for arbitrary files,
simply by passing the --no-index flag.
$ git diff --no-index <path> <path>
Using this you can generate a diff for any two files that will display in the
same format you’ve configured for Git. I use a bash alias gdiff for easy
access:
alias gdiff='git diff --no-index'