sharkdp/bat

> A cat(1) clone that adds syntax highlighting, Git change markers, and automatic paging — a terminal file viewer, not a text-stream tool.

GitHub repo · License: Apache-2.0 / MIT

Overview

bat is a command-line file viewer written in Rust, first released in 2018¹. It reads files (or stdin) and prints them with syntax highlighting for a wide range of languages, a line-number sidebar, Git modification markers relative to the working tree, and a pager for output that exceeds one screen. It is one of the more widely adopted entries in the "modern Unix rewrite" cohort (alongside ripgrep, fd, eza), and is packaged in essentially every mainstream distribution.

The defining tension is that bat is often described as a drop-in cat replacement, but it is not one in the strict sense. When output goes to an interactive terminal it adds decorations and paging; when it detects a pipe or redirect it silently falls back to plain, cat-like behavior. That context-sensitivity is deliberate and usually convenient, but it means bat in a script behaves differently than bat at a prompt, which is the source of most surprises. bat is a viewer for humans reading code, not a byte-faithful concatenation tool for pipelines.

Despite eight years of production use and near-universal packaging, bat has never shipped a 1.0 release; it remains on the 0.x line (0.26.1 as of late 2025)². This reflects the maintainer's convention rather than instability — the tool is mature and its interface has been broadly stable — but it does mean the project reserves the right to make breaking changes across minor versions.

Getting Started

# Debian/Ubuntu (note: binary may be named `batcat`, see Production Notes)
sudo apt install bat

# macOS / Linux via Homebrew
brew install bat

# from crates.io (requires Rust 1.79.0+)
cargo install --locked bat

# view a file with highlighting + line numbers
bat src/main.rs

# concatenate like cat (bat auto-detects the pipe and prints plain text)
bat header.md body.md footer.md > document.md

# force color/decorations when piping into another tool (e.g. fzf preview)
fzf --preview "bat --color=always --style=numbers --line-range=:500 {}"

# colorize man pages
export MANPAGER="bat -plman"

Architecture / How It Works

bat is a thin orchestration layer over a small number of Rust libraries, most importantly syntect³, the same syntax-highlighting engine used by several editors. syntect parses Sublime Text .sublime-syntax grammars and .tmTheme/.sublime-theme color themes. bat bundles a large set of these grammars and themes and, at build time, compiles them into a single serialized binary cache that is embedded into the executable. This is why the bat binary is several megabytes rather than the tens of kilobytes of GNU cat, and why adding a custom syntax requires bat cache --build to regenerate the cache into your config directory.

Git integration is implemented with git2 (libgit2 bindings). For each displayed file bat diffs the on-disk content against the Git index and renders added/modified/removed markers in the sidebar. This is a per-file diff against the index, not a full git diff renderer — it shows that lines changed, not the before/after content.

Paging is delegated, not built in. By default bat pipes its output to less (with flags that preserve color and disable line wrapping), controlled via --paging, PAGER, and BAT_PAGER. bat is not itself a pager; if less is absent or misconfigured, paging behavior degrades. Output-context detection is central: bat checks whether stdout is a TTY and switches between the decorated interactive path and the plain-text pipe path automatically, which is the mechanism behind its dual cat-like personality.

Production Notes

The batcat naming clash. On Debian and older Ubuntu releases the executable is installed as batcat, because the name bat collides with an unrelated existing package⁴. Scripts and docs that assume a bat binary will fail on these systems until users create a bat -> batcat symlink or alias. This is the single most common first-run confusion.

Pipe behavior is a footgun in scripts. Because bat strips decorations and color when it detects a non-interactive stdout, a command that looks colorized at the prompt produces plain text when captured in $(...), piped, or redirected. To keep color/decorations in a pipeline you must pass --color=always and/or --decorations=always (or the --force-colorization/-f alias). Conversely, do not rely on bat for byte-exact concatenation in automation where a trailing-newline or decoration difference matters — use cat.

Not free for large or streaming files. Syntax highlighting has real per-line cost, and bat loads its syntax set on startup. For very large files, log tailing, or hot loops, cat/--plain is meaningfully faster. When following logs (tail -f | bat) you must pass --paging=never and usually an explicit -l/--language, since a paged or auto-detected stream will not behave as expected.

Pager coupling. Corrupted or missing color in the pager usually traces back to less: old less versions and incorrect LESS/BAT_PAGER settings are the usual culprits. On Windows there is no system less, so paging depends on what is on PATH. The Visual C++ Redistributable is a prerequisite for the prebuilt Windows binaries.

Custom syntaxes/themes require a cache rebuild. New .sublime-syntax or theme files placed in bat --config-dir are not picked up until bat cache --build runs; bat cache --clear reverts to bundled defaults. Theme selection is via --theme/BAT_THEME, with separate --theme-dark/--theme-light (and matching env vars) added in the 0.26 line for automatic light/dark switching.

When to Use / When Not

Use when:

• You read source, configs, or logs at the terminal and want highlighting, line numbers, and Git markers without opening an editor.
• You want a better previewer for fzf, find/fd, or ripgrep results.
• You want a colorizing pager for man, --help output, or git show.

Avoid when:

• You need byte-faithful concatenation or maximum throughput in scripts and pipelines — use cat.
• You want rich side-by-side Git diffs — bat's markers only indicate changed lines; use a dedicated diff pager.
• You are on a minimal/embedded system where a multi-megabyte binary and a less dependency are unwelcome.

Alternatives

• dandavison/delta — use instead when your primary need is viewing git diff/git blame with syntax-highlighted, side-by-side output rather than viewing whole files.
• coreutils/coreutils (cat) — use for plain concatenation, scripting, and streaming where color and decorations are unwanted and startup cost matters.
• noborus/ov — use when you mainly want a modern pager (search, column mode) rather than a file viewer; can be paired with bat as its highlighter.
• walles/moar — use when you want a friendlier less replacement with built-in highlighting and simpler defaults.
• sharkdp/fd — not a bat substitute, but the companion file-finder from the same author frequently used together (fd ... -X bat).

History

References

1. ^ sharkdp/bat repository, created 2018-04-21. https://github.com/sharkdp/bat
2. ^ bat releases (v0.26.1, published 2025-12-02). https://github.com/sharkdp/bat/releases
3. ^ syntect — Rust syntax highlighting via Sublime Text grammars. https://github.com/trishume/syntect
4. ^ bat issue #982, executable name clash on Debian/Ubuntu. https://github.com/sharkdp/bat/issues/982

Tags

rust, cli, command-line, syntax-highlighting, terminal, pager, git, cat-clone, developer-tools, file-viewer