fif/README.md

<div align="center">

# fif

![A screenshot demonstrating fif's ability to detect the correct file extensions for a few files.
](https://gitlab.com/Lynnesbian/fif/-/raw/master/doc/screenshot.png)

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*A command-line tool for detecting and optionally correcting files with incorrect extensions.*
</div>

fif recursively scans the given directory and outputs a shell script to fix the name of any files with incorrect
extensions. By default, fif will scan all non-hidden files in the given directory, and will ignore symlinks.

As fif prints a shell script to stdout rather than acting on the files directly, you may wish to redirect its output to
a file, e.g. `fif ~/Documents > output.sh`. You can also pipe the output directly into your shell, e.g.
`fif ~/Documents | bash`, although this is not recommended - you should look over fif's output and verify for yourself
that it won't do anything that will give you a headache before running it.

## Features
- :white_check_mark: Cross platform
- :white_check_mark: Multi-threaded
- :white_check_mark: Configurable

## Building
fif can be built, installed, and tested with [Cargo], as with most rust programs:
```bash
git clone https://gitlab.com/Lynnesbian/fif/
cd fif
# run tests (optional)
cargo test --locked
# build fif with its default feature set
cargo build --locked --release
```
The `--locked` flag ensures that Cargo uses the dependency versions specified in [the lock
file](https://gitlab.com/Lynnesbian/fif/-/blob/master/Cargo.lock), and the `--release` flag builds fif with release
optimisations enabled -- this takes longer, but produces a much faster binary.

### Installing
```bash
# install the fif crate (to ~/.cargo/bin or %USERPROFILE%\.cargo\bin by default)
cargo install --locked fif
```

To update, simply re-run the `install` command, or use a tool like [cargo-update
](https://github.com/nabijaczleweli/cargo-update), which can update crates installed via `cargo install`.

On macOS, `fif` can be installed through [MacPorts](https://www.macports.org):
```bash
sudo port selfupdate
sudo port install fif
```

### Cargo Features
fif supports using [`infer`] or [`xdg-mime`] as its backend for looking up file types. By default, xdg-mime will be
used on [*nix systems](https://en.wikipedia.org/wiki/Unix-like) (Linux, macOS, *BSD, etc.), and infer on all other
systems.

`xdg-mime` should work on any *nix system with the [Shared MIME Info] library installed (consult your package
manager), although I've only tested it on Linux and FreeBSD. `infer` should work on any system.

You can override the default backend for your system at compile time like so:

```bash
# xdg-mime
cargo install fif --locked --features=xdg-mime-backend
# infer
cargo install fif --locked --features=infer-backend
```

It is also possible to get a more minimal build by installing without default features:
```bash
cargo install fif --locked --no-default-features
```
This will disable some non-essential but nice to have features, like multi-threading support.

For more info on fif's compile-time features, see [the wiki](https://gitlab.com/Lynnesbian/fif/-/wikis/Cargo-Features).

## Usage
See `fif --help` for more.

### The basics
The simplest way to use fif looks like this:

```bash
fif ~/Downloads
```

This command will scan all non-hidden files in your `~/Downloads` directory.

The `-e` and `-E` flags can be used to specify individual extensions and sets of extensions to scan, respectively:

```bash
# only scan files with the extensions .jpeg, .jpg, .zip, and .docx
fif -e jpeg,jpg,zip,docx ~/Documents
# only scan files with "image extensions" - .jpg, .png, .gif, .webp...
fif -E images ~/Pictures
# scan .zip files, videos, and audio
fif -e zip -E videos,audio ~/Downloads
```

Both `-e` and `-E` have equivalent `-x` and `-X` flags that exclude the given extensions rather than including them:
```bash
# scan everything except filenames ending in .zip
fif -x zip ~/Downloads
# scan all files with image extensions, but not .jpg and .jpeg files
fif -x jpg,jpeg -E images ~/Pictures
# scan everything except text and system files
fif -X text,system ~/.local/share
```

### Output
By default, fif will output a bash script (or PowerShell script on Windows) that can be used to fix all the files it
found with incorrect file extensions.

You might find it useful to output this script to a file (rather than to stdout):

```bash
fif ~/Documents > output.sh
```

You can also manually specify an output format to use:

```bash
fif -O powershell ~/Documents > output.ps1
```

### Logging
By default, fif will log any info, warnings, and errors encountered during execution. This can be changed with the `-v`
flag:
```bash
# also log debug info
fif -v ~/Downloads
# ...and trace info
fif -vv ~/Downloads
```

You can also reduce the level of logging with the `-q` flag:
```bash
# don't show info
fif -q ~/Downloads
# ...or warnings
fif -qq ~/Downloads
# ...or even errors!
fif -qqq ~/Downloads
```

The verbosity of the logging can also be modified by setting the environment variable `FIF_LOG` or `RUST_LOG` to `off`,
`trace`, `debug`, `info`, `warn`, or `error`. Values set by `FIF_LOG` override `RUST_LOG`, and both override the `-v`
and `-q` flags.

For example:

```bash
# show all levels except trace
FIF_LOG=debug fif ~/Downloads
# only show errors
FIF_LOG=error fif ~/Downloads
```

The five logging levels are used as follows:
| Level | Description | Example |
|-|-|-|
| error | Errors that cause fif to stop running | fif was unable to open the provided directory |
| warn | Warnings that don't cause fif to stop running | fif was unable to determine the mime type of a given file |
| info | Information pertaining to fif's status | The provided directory was scanned without issue, and no files are in need of renaming |
| debug | Debug information - usually not important to end users | The list of extensions fif will consider |
| trace | Trace info - usually not important to end users | "Found 15 items to check", "Scan successful", etc. |

For a more comprehensive explanation of all of fif's parameters and how to use them, run `fif --help` (or `fif -h` for
a more concise overview).

<!-- links -->
[Cargo]: https://doc.rust-lang.org/cargo/
[`xdg-mime`]: https://crates.io/crates/xdg-mime
[`infer`]: https://crates.io/crates/infer
[Shared MIME Info]: https://gitlab.freedesktop.org/xdg/shared-mime-info/


## Version policy
fif adheres to the [semantic versioning](https://semver.org/) principles. While fif remains at version 0.x, the version
number will be updated as follows:
- The MAJOR version will be bumped to 1 when I believe fif to be "feature complete".
- The MINOR version will be bumped whenever I add a fairly important feature to fif (in the past, this has been bumped
when adding the ability to exclude extensions, and when fif gained the ability to output a bash script rather than a
list of invalid filenames). The MINOR version will also be bumped when increasing the MSRV.
- The PATCH version will be bumped in all other cases, including minor feature additions (in the past, this has occurred
when adding features such as more output formats and the ignore flag).

If/when fif hits version 1.0, these rules will likely remain the same as they are now.

## License
Copyright (C) 2021 Lynnesbian

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <https://www.gnu.org/licenses/>.