kitty-diff#

A fast side-by-side diff tool with syntax highlighting and images

Major Features#

Displays diffs side-by-side in the kitty terminal
Does syntax highlighting of the displayed diffs, asynchronously, for maximum speed
Displays images as well as text diffs, even over SSH
Does recursive directory diffing

Installation#

Usage#

In the kitty terminal, run:

kitten diff file1 file2

to see the diff between file1 and file2.

Create an alias in your shell’s startup file to shorten the command, for example:

alias d="kitten diff"

Now all you need to do to diff two files is:

d file1 file2

You can also pass directories instead of files to see the recursive diff of the directory contents.

Keyboard controls#

Action	Shortcut
Quit	`Q`, `Esc`
Scroll line up	`K`, `Up`
Scroll line down	`J`, `Down`
Scroll page up	`PgUp`
Scroll page down	`PgDn`
Scroll to top	`Home`
Scroll to bottom	`End`
Scroll to next page	`Space`, `PgDn`
Scroll to previous page	`PgUp`
Scroll to next change	`N`
Scroll to previous change	`P`
Increase lines of context	`+`
Decrease lines of context	`-`
All lines of context	`A`
Restore default context	`=`
Search forwards	`/`
Search backwards	`?`
Clear search	`Esc`
Scroll to next match	`>`, `.`
Scroll to previous match	`<`, `,`
Copy selection to clipboard	`y`
Copy selection or exit	`Ctrl+C`

Integrating with git#

Add the following to ~/.gitconfig:

[diff]
    tool = kitty
    guitool = kitty.gui
[difftool]
    prompt = false
    trustExitCode = true
[difftool "kitty"]
    cmd = kitten diff $LOCAL $REMOTE
[difftool "kitty.gui"]
    cmd = kitten diff $LOCAL $REMOTE

Now to use kitty-diff to view git diffs, you can simply do:

git difftool --no-symlinks --dir-diff

Once again, creating an alias for this command is useful.

Why does this work only in kitty?#

The diff kitten makes use of various features that are kitty only, such as the kitty graphics protocol, the extended keyboard protocol, etc. It also leverages terminal program infrastructure I created for all of kitty’s other kittens to reduce the amount of code needed (the entire implementation is under 3000 lines of code).

And fundamentally, it’s kitty only because I wrote it for myself, and I am highly unlikely to use any other terminals :)

Configuration#

You can configure the colors used, keyboard shortcuts, the diff implementation, the default lines of context, etc. by creating a diff.conf file in your kitty config folder. See below for the supported configuration directives.

Diffing#

syntax_aliases#

syntax_aliases pyj:py pyi:py recipe:py

File extension aliases for syntax highlight. For example, to syntax highlight file.xyz as file.abc use a setting of xyz:abc. Multiple aliases must be separated by spaces.

num_context_lines#

num_context_lines 3

The number of lines of context to show around each change.

diff_cmd#

diff_cmd auto

The diff command to use. Must contain the placeholder _CONTEXT_ which will be replaced by the number of lines of context. A few special values are allowed: auto will automatically pick an available diff implementation. builtin will use the anchored diff algorithm from the Go standard library. git will use the git command to do the diffing. diff will use the diff command to do the diffing.

replace_tab_by#

replace_tab_by \x20\x20\x20\x20

The string to replace tabs with. Default is to use four spaces.

ignore_name#

A glob pattern that is matched against only the filename of files and directories. Matching files and directories are ignored when scanning the filesystem to look for files to diff. Can be specified multiple times to use multiple patterns. For example:

ignore_name .git
ignore_name *~
ignore_name *.pyc

Colors#

pygments_style#

pygments_style default

The pygments color scheme to use for syntax highlighting. See pygments builtin styles for a list of schemes. Note that this does not change the colors used for diffing, only the colors used for syntax highlighting. To change the general colors use the settings below.

foreground, background#

foreground black
background white

Basic colors

title_fg, title_bg#

title_fg black
title_bg white

Title colors

margin_bg, margin_fg#

margin_bg #fafbfc
margin_fg #aaaaaa

Margin colors

removed_bg, highlight_removed_bg, removed_margin_bg#

removed_bg           #ffeef0
highlight_removed_bg #fdb8c0
removed_margin_bg    #ffdce0

Removed text backgrounds

added_bg, highlight_added_bg, added_margin_bg#

added_bg           #e6ffed
highlight_added_bg #acf2bd
added_margin_bg    #cdffd8

Added text backgrounds

filler_bg#

filler_bg #fafbfc

Filler (empty) line background

margin_filler_bg#

margin_filler_bg none

Filler (empty) line background in margins, defaults to the filler background

hunk_margin_bg, hunk_bg#

hunk_margin_bg #dbedff
hunk_bg        #f1f8ff

Hunk header colors

search_bg, search_fg, select_bg, select_fg#

search_bg #444
search_fg white
select_bg #b4d5fe
select_fg black

Highlighting

Keyboard shortcuts#

Quit#

map q quit
map esc quit

Scroll down#

map j scroll_by 1
map down scroll_by 1

Scroll up#

map k scroll_by -1
map up scroll_by -1

Scroll to top#

map home scroll_to start

Scroll to bottom#

map end scroll_to end

Scroll to next page#

map page_down scroll_to next-page
map space scroll_to next-page

Scroll to previous page#

map page_up scroll_to prev-page

Scroll to next change#

map n scroll_to next-change

Scroll to previous change#

map p scroll_to prev-change

Show all context#

map a change_context all

Show default context#

map = change_context default

Increase context#

map + change_context 5

Decrease context#

map - change_context -5

Search forward#

map / start_search regex forward

Search backward#

map ? start_search regex backward

Scroll to next search match#

map . scroll_to next-match
map > scroll_to next-match

Scroll to previous search match#

map , scroll_to prev-match
map < scroll_to prev-match

Search forward (no regex)#

map f start_search substring forward

Search backward (no regex)#

map b start_search substring backward

Copy selection to clipboard#

map y copy_to_clipboard

Copy selection to clipboard or exit if no selection is present#

map ctrl+c copy_to_clipboard_or_exit

Source code for diff#

The source code for this kitten is available on GitHub.

Command Line Interface#

kitty +kitten diff [options] file_or_directory_left file_or_directory_right

Show a side-by-side diff of the specified files/directories. You can also use ssh:hostname:remote-file-path to diff remote files.

Options#

--context <CONTEXT>#: Number of lines of context to show between changes. Negative values use the number set in diff.conf. Default: -1

--config <CONFIG>#

Specify a path to the configuration file(s) to use. All configuration files are merged onto the builtin diff.conf, overriding the builtin values. This option can be specified multiple times to read multiple configuration files in sequence, which are merged. Use the special value NONE to not load any config file.

If this option is not specified, config files are searched for in the order: $XDG_CONFIG_HOME/kitty/diff.conf, ~/.config/kitty/diff.conf, $XDG_CONFIG_DIRS/kitty/diff.conf. The first one that exists is used as the config file.

If the environment variable KITTY_CONFIG_DIRECTORY is specified, that directory is always used and the above searching does not happen.

If /etc/xdg/kitty/diff.conf exists, it is merged before (i.e. with lower priority) than any user config files. It can be used to specify system-wide defaults for all users. You can use either - or /dev/stdin to read the config from STDIN.

--override <OVERRIDE>, -o <OVERRIDE>#: Override individual configuration options, can be specified multiple times. Syntax: name=value. For example: -o background=gray

Sample diff.conf#

You can download a sample diff.conf file with all default settings and comments describing each setting by clicking: sample diff.conf.