repvar - Variable replacing, UNIX-style text filter

A tiny CLI tool that replaces variables of the style ${KEY} in text with their respective value. It can also be used as a rust library.

For the CLI tool, the variables can be read from the environment or be directly supplied through CLI switches, like -Dkey=value.

NOTE
The author is a rust-newb. This crate probably only makes sense for himself, and it is not using the power of rust as should be. It also could probably be written in just 10 lines of code, using one or two regexes, not loosing any performance.

Usage

Simplistic

$ export KEY_A="replacement"   # setting an env.-variable
$ echo 'Text ${KEY_A}.' \      # input text
    | repvar --env             # replacing variables
Text replacement.              # output

Slightly more elaborate

$ export first="the environment"
$ echo 'Variables from ${first}, ${second}, ${not_supplied} and $${quoted}.' \
    | repvar --env -D"second=the CLI"
Variables from the environment, the CLI, ${not_supplied} and ${quoted}.

More usage info can be seen when running:

repvar --help

Building

# To get a binary for your system
cargo build --release

# To get a 64bit binary that is portable to all Linux systems
run/rp/build

Testing

To run unit-, doc- and integration-tests:

run/rp/test

Similar projects

• More powerful string templating engine, but very much in line with the unix philosophy as well https://github.com/nilsmartel/string

Funding

This project was funded by the European Regional Development Fund (ERDF) in the context of the INTERFACER Project, from August 2021 (project start) until March 2023.