# bagex

## Synopsis

`bagex` serves as an entrance for programs, it manages environment variables
for the programs according to a configuration file.

## Configuration

The configuration file is in [toml](https://github.com/toml-lang/toml) format,
and consists of 3 parts: `path`, `env`, and `exe`.

- `path`: It is an array of paths, which will be **prepended** to the
  environment variable `$PATH` when `bagex` tries to find a executable.
- `env`: This section creates multiple one-to-many mappings _from an
  environment variable to some executables_.
- `exe`: This section creates multiple one-to-many mappings _from an
  executable to some environment variables_.

An illustrative example configuration can be found [here](./config.toml).

## Usage

`bagex` takes an executable name as its argument, and tries to read its
configuration from `$XDG_CONFIG_HOME/bagex/config.toml` if the environment
variable `XDG_CONFIG_HOME` is set, otherwise it tries to read
`$HOME/.config/bagex/config.toml`.  Optionally use `-c|--config-file` to
specify the configuration file to read.  Example usage:

```shell
$ cat config.toml
[env.answer_to_the_ultimate_question_of_life_the_universe_and_everything]
42 = [
    "printenv",
]
[exe.printenv]
some_random_string = "YmFnZXgK"
pi = 3.14

$ bagex -c config.toml printenv
[..truncated..]
answer_to_the_ultimate_question_of_life_the_universe_and_everything=42
pi=3.14
some_random_string=YmFnZXgK
```

To add arguments for the requested executable (`printenv` in the above
example), append the arguments after a double dash (`--`):

```shell
$ bagex -c ./config.toml bagex -- --version
bagex 0.1.0
```

Use `-d|--dry-run` to show the command to run and abort:

```shell
$ bagex -c ./config -d echo -- -en "Hello  world!"
/sbin/echo "-en" "Hello  world!"
```

## Use cases

### Systemd services

It _is_ quite convenient to set a process' environment in a systemd service,
but every time the environment has to change, one must run `systemctl [--user]
daemon-reload` after changing the `.service` file, then call `systemctl
[--user] restart foo.service` to update the running environment of the
program.

`bagex` makes this process even more convenient by specifying the environment
of a program in a separate config file, so that each time the environment is
changed in `bagex`'s config, only a `systemctl [--user] restart foo.service`
has to be called.

### Application launchers (like rofi, sxhkd, etc.)

`bagex` can be used as a backend for application launchers.  The functionality
`bagex` provides is basically an application launcher with an environment
managing module.  After creating the configuration file, invoke bagex through
the application launchers so that the environment variables are the way the
config file specifies.

## License

[MIT](./LICENSE)