estebanborai/file-copycat

A library that writes a copy of a watched file on write with optionally replacing bytes on write.

This crate is a WIP.

Usage

Create a new binary crate and reference this crate wherever it is:

[package]
name = "test-file-copycat"
version = "0.1.0"
edition = "2018"

# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

[dependencies]
file-copycat = { path = "relative/path/to/the/crate" }

Create two files, one is the input file you want to watch changes for (./testfile.txt). The other is the output file you want to write on (./outputfile.txt).

Then paste the following code into the main.rs file

use file_copycat::watch;
use std::str::from_utf8;

fn main() {
    let replacer = |input: Vec<u8>| {
        let mut utf8 = from_utf8(&input).unwrap();
        let replaced = utf8.replace("hello", "goodbye");

        replaced.as_bytes().to_vec()
    };

    if let Err(err) = watch("./testfile.txt", "./outputfile.txt", Box::new(replacer)) {
        println!("{:?}", err);
    }
}

file-copycat's Issues

Append to output file instead of replacing whole contents

Currently when writing the output file, contents are entirely replaced.
Instead would be great to have bytes appended to the output file.

Open the output file and do not close it until the process is terminated

Currently we open and close (dispose) the output file on every write.
Instead would be great to just have it open, write to it via a stream and close the file just before terminating the process.

We could use a EOF or Ctrl+C aware event stream to run the desired "cleanup" process.