I'm currently working on a pure-Rust
tr utility, with the intention of getting it into Redox.
Additionally, I've opted for a fully GNU-compatible program because it looked like an interesting challenge. Turns out I used way less of
tr than it's actually capable of... I've already implemented parsing goddamn octal sequences for specifying ASCII codes (hello 70s!). After I'm done with GNU compatibility I'll add a -u key or something to specify Unicode codepoints in hexadecimal. (You're welcome to strip away GNU compatibility and make that the default mode if you think that's a good idea).
Also, right now the commandline argument parsing is done by hand, and it doesn't handle abbreviated commandline options clamped together, like
tr -sd (while
tr -s -d works fine). I don't feel like reimplementing that part by hand, so if you port Clap or some other parser for command-line options to Redox please let me know and I'll switch my tr to it ASAP.