# A wrapper function to convert e-books using Calibre

This function calls the command `ebook-convert` in Calibre
(<https://calibre-ebook.com>) to convert e-books.

## Usage

``` r
calibre(input, output, options = "")
```

## Arguments

- input:

  The input filename.

- output:

  The output filename or extension (if only an extension is provided,
  the output filename will be the input filename with its extension
  replaced by `output`; for example, `calibre('foo.epub', 'mobi')`
  generates `foo.mobi`).

- options:

  A character vector of additional options to be passed to
  `ebook-convert`.

## Value

The output filename.