# Less full of colors


[`less`](https://www.man7.org/linux/man-pages/man1/less.1.html) is the workhorse of the terminal, but by default it dumps source files onto the screen as monochrome text. You can pipe files through a highlighter manually, but the nicer solution is to make it automatic: configure your shell so that *every* time you run `less` on a code file, GNU source-highlight colors it for you.

Based on [Viewing more with less – color syntax](https://dev.to/vvidovic/viewing-more-with-less-color-syntax-hhp) by Vedran Vidovic, here's the permanent setup.

#### `The` Setup

The whole thing rests on two environment variables that `less` reads. First, install the highlighter (Debian/Ubuntu naming):

```plaintext
brew install source-highlight
```

Then append this to your `~/.`zshrc (or `~/.profile` if you prefer login-shell scope):

```bash
# less syntax highlighting + source-highlight installation
export LESSOPEN="| /opt/homebrew/Cellar/source-highlight/3.1.9_6/bin/src-hilite-lesspipe.sh %s"
export LESS=' -R'
```

Reload your shell config or open a new terminal:

```bash
source ~/.bashrc
```

From that point on, any file you open by name — `less main.go`, `less config.json`, `less` [`script.py`](http://script.py) — arrives already colorized. No wrapper aliases, no remembering extra flags; it just becomes the default behavior of `less`.

#### Why These Two Lines Work

`LESSOPEN` is the hook that does the heavy lifting. When `less` opens a file, it runs the command after the pipe symbol as an *input preprocessor*, with `%s` standing in for the filename. Here the preprocessor is [`src-hilite-lesspipe.sh`](http://src-hilite-lesspipe.sh), a small bridge script shipped with the source-highlight package that detects the file's language and emits colorized output for `less` to display.

`LESS=' -R'` is the necessary companion. Terminals show colors through raw ANSI escape sequences, and without `-R`, `less` would neutralize them into literal `^[[` gibberish. The `-R` flag tells `less` to pass raw control characters through so the colors actually render. Note the leading space in the value — it's the standard way of placing the option without disturbing any `LESS` value you might set elsewhere.

#### Caveats Worth Knowing

The automatic highlighting applies to files `less` opens *by name*, since that's what `LESSOPEN` receives — piping content in (`cat file | less`) bypasses the preprocessor. The script path is also distribution-specific; if you're not on Debian/Ubuntu, check where your package placed [`src-hilite-lesspipe.sh`](http://src-hilite-lesspipe.sh). And if a language isn't supported out of the box (YAML, for instance), source-highlight accepts custom language definitions that you can drop into its configuration directory.

It's a five-minute setup that quietly improves every future code-reading session in the terminal — and as the original article's screenshots show, the difference between highlighted and plain `less` output is immediately obvious the first time you open a JSON file.

Notice pipelining and redirect output between scripts does bring small increase of memory foorprint for less command, but hey! Colors are colors, no?