How can I get a side-by-side diff when I do "git diff"?

Try git difftool

Use git difftool instead of git diff. You'll never go back.

UPDATE to add an example usage:

Here is a link to another stackoverflow that talks about git difftool: How do I view 'git diff' output with my preferred diff tool/ viewer?

For newer versions of git, the difftool command supports many external diff tools out-of-the-box. For example vimdiff is auto supported and can be opened from the command line by:

cd /path/to/git/repo
git difftool --tool=vimdiff

Other supported external diff tools are listed via git difftool --tool-help here is an example output:

'git difftool --tool=<tool>' may be set to one of the following:
        araxis
        kompare
        vimdiff
        vimdiff2

The following tools are valid, but not currently available:
        bc3
        codecompare
        deltawalker
        diffuse
        ecmerge
        emerge
        gvimdiff
        gvimdiff2
        kdiff3
        meld
        opendiff
        tkdiff
        xxdiff

Although Git has an internal implementation of diff, you can set up an external tool instead.

There are two different ways to specify an external diff tool:

1. setting the GIT_EXTERNAL_DIFF and the GIT_DIFF_OPTS environment variables.
2. configuring the external diff tool via git config

ymattw's answer is also pretty neat, using ydiff

See also:

• https://git-scm.com/book/en/v2/Customizing-Git-Git-Configuration
• git diff --help
• http://www.pixelbeat.org/programming/diffs/

When doing a git diff, Git checks both the settings of above environment variables and its .gitconfig file.

By default, Git passes the following seven arguments to the diff program:

path  old-file  old-hex old-mode  new-file  new-hex new-mode

You typically only need the old-file and new-file parameters. Of course most diff tools only take two file names as an argument. This means that you need to write a small wrapper-script, which takes the arguments which Git provides to the script, and hands them on to the external git program of your choice.

Let's say you put your wrapper-script under ~/scripts/my_diff.sh:

#!/bin/bash
# un-comment one diff tool you'd like to use

# side-by-side diff with custom options:
# /usr/bin/sdiff -w200 -l "$2" "$5" 

# using kdiff3 as the side-by-side diff:
# /usr/bin/kdiff3 "$2" "$5"

# using Meld 
/usr/bin/meld "$2" "$5"

# using VIM
# /usr/bin/vim -d "$2" "$5"

you then need to make that script executable:

chmod a+x ~/scripts/my_diff.sh

you then need to tell Git how and where to find your custom diff wrapper script. You have three choices how to do that: (I prefer editing the .gitconfig file)

1. Using GIT_EXTERNAL_DIFF, GIT_DIFF_OPTS

   e.g. in your .bashrc or .bash_profile file you can set:

    GIT_EXTERNAL_DIFF=$HOME/scripts/my_diff.sh
    export GIT_EXTERNAL_DIFF
   

2. Using git config

   use "git config" to define where your wrapper script can be found:

    git config --global diff.external ~/scripts/my_diff.sh
   

3. Editing your ~/.gitconfig file

   you can edit your ~/.gitconfig file to add these lines:

    [diff]
      external = ~/scripts/my_diff.sh
   

Note:

Similarly to installing your custom diff tool, you can also install a custom merge-tool, which could be a visual merging tool to better help visualizing the merge. (see the progit.org page)

See: http://fredpalma.com/518/visual-diff-and-merge-tool/ and https://git-scm.com/book/en/v2/Customizing-Git-Git-Configuration

You can also try git diff --word-diff. It's not exactly side-by-side, but somehow better, so you might prefer it to your actual side-by-side need.

ydiff

Formerly called cdiff, this tool can display side by side, incremental, and colorful diff.

Instead of doing git diff, do:

ydiff -s -w0

This will launch ydiff in side-by-side display mode for each of the files with differences.

Install with:

python3 -m pip install --user ydiff

-or-

brew install ydiff

For git log, you can use:

ydiff -ls -w0

-w0 auto-detects your terminal width. See the ydiff GitHub repository page for detail and demo.

Tested in Git 2.18.0, ydiff 1.1.

You can do a side-by-side diff using sdiff as follows:

$ git difftool -y -x sdiff  HEAD^ | less

where HEAD^ is an example that you should replace with whatever you want to diff against.

I found this solution here where there are a couple of other suggestions also. However, this one answer's the OP's question succinctly and clearly.

See the man git-difftool for an explanation of the arguments.

Taking the comments on board, you can create a handy git sdiff command by writing the following executable script:

#!/bin/sh
git difftool -y -x "sdiff -w $(tput cols)" "${@}" | less

Save it as /usr/bin/git-sdiff and chmod +x it. Then you'll be able to do this:

$ git sdiff HEAD^

Extra Tip

As suggested in comments you can use icdiff to do what sdiff does with colored output:

$ more /usr/bin/git-sdiff
#!/bin/sh
git difftool -y -x "icdiff --cols=$(tput cols)" "${@}" | less