Muter is a tool to convert to and from various data formats, such as hexadecimal, Base64, and URI encoding.

Use

Muter takes a series of bytes like cat (as filenames or from standard input) and produces a byte sequence to standard out. The bytes are modified by the argument to -c (--chain) that specifies the encodings to perform.

For example, a chain of -hex:base64 decodes hex input and then re-encodes the data in Base64. base64:uri would Base64-encode the data, and then URI-encode it, but url64 would just encode using the URL-safe version of Base64. A chain of hash(sha256):hex would hash the input data and then hex-encode the SHA-256 hash.

Muter is written in Rust and supports Rust 1.34.2 or newer. You can simply run cargo build --release to build it. If you’d like to build the documentation, install Asciidoctor and GNU make, and type make all doc, and the man page will be in doc/. The help output is also generally helpful.

While Muter lacks translations, it is designed to be localized. Please open an issue if you’re interested in submitting a translation.

If you’re looking for the older Perl version, you can find it in the perl branch.

Examples

# URI-decode some data, then HTML-encode it
$ muter -c -uri:xml,html my-data >foo.html

# Generate a subresource integrity hash
$ printf 'sha256-'; \
  curl -s https://code.jquery.com/jquery-3.2.1.js | muter -c hash,sha256:base64
sha256-DZAnKJ/6XZ9si04Hgrsxu/8s717jcIzLy3oi35EouyE=

# Encode a password for use with curl
$ curl https://user:$(printf 'very-complex/pass' | muter -c uri)@example.org

Transforms

The following transforms are available, many with multiple options:

• ascii85

• base16

• base32

• base32hex

• base64

• bubblebabble

• checksum

• crlf

• deflate

• form

• gzip

• hash

• hex

• identity

• lf

• modhex

• quotedprintable

• uri

• url64

• uuencode

• vis

• wrap

• xml

• zlib

For a full description of the transforms that are available, see the manual page.

If you’re interested in a new transform, feel free to open an issue. Note that we try to ensure that transforms are deterministic and that they round-trip if there’s a reverse variant, but sometimes we make exceptions. We also generally prefer that the decoder encode all variants that the encoders can produce without any arguments.

Name

Muter comes from the Spanish verb mudar and the French verb muter, meaning to mutate, since what it does is, well, mutate data.

The name is pronounced /ˈmjuːtər/ (MEW-ter).