# is_required

List which Slackware SBo packages depend on a given package, and whether each is installed.

Given a package name, `is_required` searches the SlackBuilds.org (SBo) git tree for `.info` files whose `REQUIRES=` field names that package (whole-word match), then marks each dependent as installed or missing by checking `/var/log/packages`.

## Usage

```
is_required [OPTIONS] <package>
```

### Options

| Flag | Effect |
|------|--------|
| `-i` | show only installed dependents |
| `-u` | show only uninstalled dependents |
| `-r` | recursive: also show packages that require those dependents (one level up) |
| `-h` | help |

### Example

```
$ is_required ffmpeg
Packages requiring 'ffmpeg':
────────────────────────────────────────────────────
[I] mpv                                       (multimedia)
[ ] obs-studio                                (multimedia)
```

### Output legend

- `[I]` — installed (present in `/var/log/packages`), bold green
- `[ ]` — not installed, yellow
- `<package>` — queried package name in the header, bold cyan
- `(category)` — SBo category of the dependent, dim white

Color is auto-disabled when stdout is not a terminal (piped or redirected).

## Configuration

Both paths are overridable via environment variables:

| Variable | Default | Meaning |
|----------|---------|---------|
| `SBO_REPO` | `/var/lib/sbopkg/SBo-git` | SBo git tree to search |
| `PKG_LOG` | `/var/log/packages` | installed-package log |

Package names are derived from `/var/log/packages` filenames by stripping the trailing version, arch, and build-tag fields (e.g. `ffmpeg-7.1.4-x86_64-1` → `ffmpeg`).

> **Note:** `/var/log/packages` is a symlink to `/var/lib/pkgtools/packages`, so `find` is run with `-follow`.

## Bash completion

`is_required.bash` completes option flags and installed package names (read from `$PKG_LOG`).

Install system-wide:

```bash
sudo cp is_required.bash /etc/bash_completion.d/is_required
```

Or per-user (requires `~/.bash_completion.d/` sourced in `~/.bashrc`):

```bash
cp is_required.bash ~/.bash_completion.d/is_required
```

## Requirements

- Bash 4+ (uses associative arrays)
- Standard SlackBuilds tooling layout (`sbopkg` SBo-git tree, `pkgtools` package log)