Linux

Like many others, I don't replace old tools with new ones, simply because it is written in Rust. For example, fzf is a very novel and useful tool that's written in Go. (FYI: Fzf has a Rust alternative called skim). I'm going to restrict the rest of the post to the context of this thread - Rust CLI/TUI programs that I like. But by no means are they the only new ones I like, or always a replacement for the old ones.

fd and ripgrep (rg) have 2 things in common that give them edge over their older counterparts. First is that both are extremely fast compared to their predecessors. Second is that both support a modern (perl-compatible) version of regex syntax that many programming languages support.

Zellij is a terminal multiplexer like Tmux. However, Zellij IMO has one huge advantage over Tmux and screen - you don't need to take a tutorial or read a user guide just to get started. Everything is discoverable and intuitive. Zellij has the potential to replace TMux as the dominant terminal multiplexer in the near future.

You may find zoxide, atuin and starship as good extensions to your terminal experience, depending on your tastes. Zoxide is a smart directory changer (alt for cd) with good integration all around - with a lot of shells, alternatives (data import), editors (emacs, nvim, etc), file browsers (ranger, nnn, etc) and even mail client (aerc). Atuin replaces the history part of GNU Readline. But lately, it has started gaining features not found in readline, like encrypted history and cross-device history sync. Starship may be a bit fancy for shell prompts - but I find its configuration format to be simpler than the old method. It also supports several shells giving you a uniform experience across shells.

GPG-TUI is a TUI frontend to GnuPG. It's useful simply because the GnuPG UI is terrible. Meanwhile, Sequoia PGP is a tool that aims to replace GnuPG altogether. It has some lofty ambitions and has forced the OpenPGP ecosystem to advance a bit. Some of their innovations aim to solve the drawbacks of old OpenPGP - like lack of PKI (instead of just WoT) and Perfect forward secrecy in certain modes. Its defaults are also more sane and modern compared to GnuPG.

Git-UI (Rust) and LazyGit (Go) are TUI frontends for Git - they have no alternatives. I can recommend either of them if you are a heavy user of git - especially interactive staging and interactive rebasing. Meanwhile, git-interactive-rebase-tool is a tool specifically designed to manage interactive rebases.

If you are into coding, you may find Tokei useful. It is tool for counting Lines of code (LoC) in your projects, segregated by language. Hyperfine, from the developer of fd, is used to benchmark applications over several runs, with a lot of configuration options. Bat is a terminal pager, again from the developer of fd. It supports syntax highlighting. I often find uses for that. I'm not aware of another tool with the exact same functionality.

Finally, nushell is showing a lot of promise as a shell with more modern features. It extends the structured data paradigm from powershell.