# Sin

> 🙏 Forgive me father for I have simply inhibited.

**S**imple **In**hibitor (Sin) watches `/proc` for processes matching your
patterns and inhibits system idle/sleep while they run.

## Why

Your system shouldn't sleep while you're watching a movie, compiling code, or
running a long task. Sin prevents that by talking to systemd-logind when your
processes are active.

I think this is should be a part of the idle program itself, but I could not
find an idle daemon that supports this feature. Naturally I made one of my own.
You are welcome to use it if this fits your needs. It is easy to **S**imply
**In**hibit.

This is an _alternative_ to handling inhbiting on a compositor level, and is
aimed to detect things a compositor generally cannot. In the case of, e.g.,
desktop applications I recommend letting your compositor handling the inhibit. I
might also support this for Sin in the future.

## How it works

1. You tell Sin which processes to watch (e.g., `mpv`, `steam`, `ffmpeg`)
2. Sin scans `/proc` every few seconds looking for them
3. When found, it grabs a Systemd inhibitor lock
4. When they exit, it releases the lock
5. Your system can sleep again

Great success!

## Usage

```bash
# Keep system awake while Firefox is running
sin -n firefox

# Watch multiple processes
sin -n steam -n "wine " -n lutris

# Prevent sleep (not just idle) while rendering
sin -n blender --what=sleep

# Custom poll interval
sin -n mpv --poll=1.0
```

### Options

```plaintext
-n, --name PATTERN     Process cmdline substring to watch (required, repeatable)
--what WHAT           What to inhibit: idle, sleep, shutdown, etc. (default: idle)
--mode MODE           block or delay (default: block)
--poll SECONDS        How often to check (0.1-3600, default: 2.0)
-d, --daemon          Run as daemon (fork to background)
-q, --quiet           Suppress informational output
-v, --version         Show version
-h, --help            Show help
```

## Building

```bash
make
sudo make install
```

Requires:

- GCC or Clang
- libsystemd

That's it.

## Examples

```bash
# Don't idle while gaming
sin -n steam -n wine

# Keep system awake during long builds
sin -n "cargo build" -n "nix build"

# Prevent sleep while watching videos
sin -n mpv -n vlc --what=sleep

# Fast polling for responsive tasks
sin -n ffmpeg --poll=0.5

# Run as daemon
sin -d -n mpv -n vlc
```

## Running as a Service

A systemd service file is provided in `vendor/sin.service`. Edit it to match
your needs:

```bash
# Copy and customize the service file
sudo cp vendor/sin.service /etc/systemd/system/
sudo nano /etc/systemd/system/sin.service  # Edit the ExecStart line

# Enable and start
sudo systemctl enable --now sin.service
```

## Why not just use...?

### Systemd-inhibit

There are a few alternative options that you could go with. Namely, Sin is
inspired by the operating principle of `systemd-inhibit` among those options,
but prefers an approach similar to EarlyOOM where you provide the programs that
you want to watch instead of launching the program with a systemd-inhibit
wrapper.

### Caffeine

While researching, I've noticed programs such as **caffeine** and
**caffeine-ng** but ultimately decided against those since they seem to be
hooking up to more specific APIs than Systemd's own. I also find Python to be
unsuitable for production, and have elected to use C for a smaller and faster
binary that is easier to bootstrap.

If you _do_ use those tools, and would like to try out Sin but cannot make a
switch due to missing features, please do create an issue. While I do not wish
to support screenlocker-specific APIs, I am happy to implement more generic
features such as a tray icon. Maybe even support for other init systems in the
future.

### Hand-written Systemd Service

Sure, if you'd like to write one yourself. Sin is that Systemd service in my
case. Give it a try, maybe I've saved you from some code spent fixing a trivial
problem.

## Attributions

[Diniamo]: https://github.com/diniamo
[Wayhibit]: https://github.com/diniamo/wayhibitor

This project was inspired partially by [Diniamo]'s [Wayhibit], which deserves
the primary attribution here. I'd also like to thank Systemd developers for
`systemd-inhibit`, which has inspired me to write this project and also for the
sd-bus API that makes Sin possible.

## License

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[here]: https://interoperable-europe.ec.europa.eu/sites/default/files/custom-page/attachment/eupl_v1.2_en.pdf

This project is made available under European Union Public Licence (EUPL)
version 1.2. See [LICENSE](LICENSE) for more details on the exact conditions. An
online copy is provided [here].

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