tomato-toml 0.2.0

🍅 A command-line tool to get and set values in toml files while preserving comments and formatting.
tomato-toml-0.2.0 is not a library.


Test the tomato

Get, set, and delete values in TOML files while preserving comments and formatting.

That's it. That's the feature set. I wrote tomato to satisfy my own primary use case, which is to read values of various types from a TOML preferences file, process those values in bash tooling, and infrequently update those values from other bash scripts.

To install:

# using homebrew:
brew tap ceejbot/tap
brew install

# if you have rust installed and prefer to build from source:
cargo install tomato-toml

# once installed:
tomato --help

Or snag a pre-built executable from the releases.

An alternative tool would be dasel, if you don't need to preserve comments and formatting when you modify a value. dasel also supports a large variety of file formats.

If you need to convert among JSON, YAML, and TOML, check out jyt.


The short version:

  • Get a key: tomato get <file> <dotted.key>
  • Set a key: tomato set <file> <dotted.key> <value>
  • Delete a key: tomato rm <file> <dotted.key> (with lots of aliases for rm)

The set and rm subcommands modify the input file in place. Thanks to the magic of toml_edit, they do so without disturbing whitespace and comments.

By default tomato emits data a form suitable for immediate use in bash scripts. Strings are unquoted, for instance. The bash format generates output suitable for eval inside bash. Use this for arrays and associative arrays. If you need to consume more complex output, you might select json format and pipe the results to jq. And of course if you need TOML, use toml.

The longer version:

🍅 tomato 0.2.0
A command-line tool to get and set values in toml files while preserving comments and formatting.

Keys are written using `.` to separate path segments. You can use `array[idx]` syntax to index into
arrays if you want to. For example, to get the name of the current crate you're working on, you'd
run `tomato Cargo.toml get`.

By default tomato emits data in a form suitable for immediate use in bash scripts if they are
primitive values: strings are unquoted, for instance. If you want to use more complex data types,
consider one of the other output formats.

To read from stdin instead of a file, pass '-' as the filename. Operating on stdin changes the
behavior of set and rm somewhat, under the assumption that you are using this tool in a shell
script. If you read from stdin, normal output (the old value) is suppressed. Instead the modified
file is written to stdout in json if you requested json, toml otherwise. The 'bash' format option is


	-b, --backup
			Back up the file to <filepath>.bak if we write a new version. This option is ignored
			when we're operating on stdin

	-f, --format <FORMAT>
			How to format the output: json, toml, bash, or raw
			[default: raw]

	-h, --help
			Print help information

	-V, --version
			Print version information

	get     Get the value of a key from the given file
	set     Set a key to the given value, returning the previous value if one existed
	rm      Delete a key from the given file, returning the previous value if one existed
			Generate completions for the named shell
	help    Print this message or the help of the given subcommand(s)

get and rm both print empty string to stdout if the target key is not found. set exits with a non-zero status with a message printed to stderr if the target key is not found.


Here are some examples run against the Cargo manifest for this project:

$ tomato get Cargo.toml
$ tomato --format json get Cargo.toml
$ cat Cargo.toml | tomato get -

# set examples
$ tomato set Cargo.toml broccoli
$ tomato set Cargo.toml package.keywords[1] yaml

# Keys that don't exist
$ tomato get Cargo.toml dependencies.toml_edit[0]

$ tomato set Cargo.toml dependencies.toml_edit[0] "first!"
Error: unable to index into non-array at dependencies.toml_edit.0

# rm has a number of aliases to prevent user frustration
$ tomato --format json del Cargo.toml package.categories[0]

Look at the examples/ directory for some sample bash scripts with more varied examples, including examples of using lists and associative arrays in bash.


Remaining work:

  • complete the tests
    • datetimes
    • tables
    • arrays of tables


Heck, yeah! Please keep the major use case in mind: you need to read toml and do stuff with it in bash. I'm happy to accept anything that improves that use case or makes the Rust parts better.


Blue Oak Model License; text in