An Answer to Rewritten in Rust

Published: · Modified: · b0364f7

This post is some kind of an answer to Rewritten in Rust: Modern Alternatives of Command-Line Tools.

The creation of the Rust programming language has created a lot of momentum in the free software community. They praise Rust with the slogan:

A language empowering everyone to build reliable and efficient software.1

The focus of Rust is on “Performance”, “Reliability”, and “Productivity”1.

A few years ago, I started my engineering “career” with digging through horrible, proprietary, and ugly embedded C code. Once I discovered Rust, I was quite hyped by its goals. Finally we have a tool to fix enterprise guys writing bad C code and we can eventually improve all tooling… Not a bit of it! In the following I want to give an overview where “Modern Alternatives” of well known programs in Rust miss the point or are actually improvements.

First let’s clarify my workflow. I have two usage profiles on my computer:

Automated

For the “automated” profile I accept nothing but tools which are almost always available on my machines2. Further, I rely on stable and documented interfaces.

Examples for such tools are:

All these tools have in common that they have a stable interface for scripting3. These interfaces might or might not be optimized for modern usage, such as the availability of structured data, for instance JSON. But they are well known and consequently there is tons of high quality documentation and resources available.

If I ever accept a new tool for my automated profile, it MUST meet my requirements of availability and stability. I consider a tool as stable if it hadn’t broken my scripts in the past; preferably the behaviour of the tool is standardized by e.g. POSIX. I consider a program available when it is present in the standard installation of a Linux distribution (best), or when it is available in the standard package repositories (ok). I consider a program not available if I need to use a tool like pip or cargo to install it (bad), or if I even need to compile it from source from scratch (worst). I maintain a lot of machines and I will get lost otherwise. Bonus points: The Linux distros' package maintainers do a wonderful job and I can totally rely on them for specifying dependencies and everything correctly.

Interactive

My “interactive” profile is quite different. Since I am used to do almost everything in the terminal, tools must be efficient and easy to remember. I am a bit more relaxed about the stability requirement here. Since I have the tools under my fingers every day, I can adapt to changes or new features rather quickly with learning by doing. What’s more important for me is: features that differ from the automated profile must be minimal and easy to remember. Otherwise I forget about them and won’t use them. Examples for good tools for my interactive profile are:

Now it starts to get interesting. There is an overlap in my very subjective list of tools: git and coreutils. Excellent software for me: scriptable and usable interactively. That should be the default for all software we write!

Now to Rust

The Rust community has created a lot of software the last years, this blog post shows a few of them. Most of them address only my interactive profile, since I won’t consider them available and stable. That’s simply caused by their age which is understandable. Let’s examine what these tools improve for me.

exa

The exa tool is:

a replacement for ls written in Rust.

Ok. That’s what the title of this blog post is all about. Further the rational is:

exa is a modern replacement for the command-line program ls that ships with Unix and Linux operating systems, with more features and better defaults. It uses colours to distinguish file types and metadata. It knows about symlinks, extended attributes, and Git. And it’s small, fast, and just one single binary.

Let’s do a quick check in my current working dir:

$ exa -la --color=always | head
thread '<unnamed>' panicked at 'called `Result::unwrap()` on an `Err` value: SystemTimeError(6795364578.871345152s)', src/fs/file.rs:331:9
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
fish: Process 139566, “exa” “exa -la --color=always | head” terminated by signal SIGABRT (Abort)

Okay… Then let’s do a quick check in the Linux kernel tree:

$ command time -p ls -R > /dev/null
real 0.09
user 0.05
sys 0.03
$ command time -p exa -R > /dev/null
real 0.30
user 0.15
sys 0.14

exa is fast, but ls is faster. exa extensively uses colors claiming that it improves the situation for the user:

screenshot of ls and exa

The sorting is different, there are column headers, the group is abscent, and there are a lot of colors… I know this is a question of taste, but for me these colors add no value at all. They are even confusing for me, since I can’t parse what kind of information they actually encode.

second screenshot of ls and exa

Why are README and Makefile underlined and yellow? Rewritten in Rust, but I don’t see the real reason why this is important. For learning Rust it is a nice project. For actually improving the ecosystem, I am not sure.

fd

This tool sounds interesting:

fd is a fast and user-friendly alternative to find, the built-in command-line program in Unix/Linux for walking a file hierarchy. fd provides opinionated defaults for the most common use cases. To find a specific file by name, you write fd PATTERN instead of find -iname "*PATTERN*". fd is also extremely fast and it comes with a ton of options like ignoring hidden directories, files and patterns from .gitignore by default.

Let’s try it in the kernel tree:

$ fd vcan.c
drivers/net/can/vcan.c

find is a little more complex:

$ find . -name vcan.c
./drivers/net/can/vcan.c

Nice! I compared the performance of them with time, the result are quite the same. Since I always forget the find flags and I always have to look them up in the manpage, I like this tool. It is reasonably fast and it respects .gitignore files which is nice, too. Regular expressions and globs are supported as well and most importantly it has a manpage. Added to my interactive profile, fd is simple and in contrast to find easy to remember.

dust

This one is really cool and actually an improvement over du -sh.

dust is a more intuitive version of du, the built-in command-line program in Unix/Linux for displaying disk usage statistics. By default dust sorts the directories by size.

The delta to du -sh really is the graphical respresentation of the file and directory sizes. Also the tool name ist well chosen, since it begins with the same letters plus the -st flags of du. A picture shows it best:

screenshot of ls and exa

I am not sure if I often need such a tool. There is ncdu which is more powerful in the interactive profile.

procs

This tool claims to:

procs is a modern replacement for ps, the default command-line program in Unix/Linux for getting information about processes. It provides convenient, human-readable (and colored) output format by default.

Let’s check it out! For comparison with the next picture I addet the -t flag for the tree view.

screenshot of ls and exa

Okay. Once again I am not sure which information is actually encoded by the colors. For the automated profile it is not a replacement for ps. In the interactive profile, there is htop for getting information about processes. In contrast to procs, htop uses colors sparingly and the interface is well thought. For example, colors are used to outline differences. root is shown in a different color than my user. The resource utilization columns use colors to highlight bytes, megabytes, and gigabytes differently. The procs tool just colorizes everything in the same color which carries no information at all.

screenshot of ls and exa

Further, in htop the tree view is designed that the user can follow the branches easily. I leave comparing the visualization with the procs tool as an excercise to the reader. These are the little differences where I prefer an old tool over a “modern” one.

bat

A long time ago while learning Python I wrote c.py. As a novice, I thought it might be a good idea to actually have this kind of functionality the bat tool claims to have:

bat is a cat clone with syntax highlighting and Git integration that works on Windows, MacOS and Linux. It provides syntax highlighting for many file extensions by default.

I can stop here. Usually I fire up nvim and I have even more power. I realized this very fact with my own tool and I abandoned it. Syntax highlighting is a nice feature but the problem here is the scope of the tool. It is not a text editor which has syntax highlighting builtin anyway. So for me there is no added value.

sd

Tho sd tool (s[earch] & d[isplace]) claims:

sd is an intuitive find & replace CLI.

I got tired of trying out each and every tool on my list. The authors provide a really good example list, why this tool shines (and it is not about colors!). I took the liberty to copy these examples from the README on Github:

I am not sure if I would actually use this tool, since it took me a long time to somehow master sed. But it seems the authors designed the tool well and they thought about what needs to be done designing a user friendly search and replace tool.

ripgrep

Coming from the silver searcher, ripgrep was my first Rust tool I used.

ripgrep is an extremely fast alternative to grep, the built-in command-line program in Unix/Linux for searching files by pattern. ripgrep is a line-oriented search tool that recursively searches your current directory for a regex pattern. By default, ripgrep respects .gitignore and automatically skips hidden files, directories and binary files.

I use it every day and it just works. The author himself provides a comprehensive explanation. I better refer to him in this case.

Features why I use it over grep -r are: speed and the fact that .gitignore files are respected. Features why I use it over the silver searcher: It is written in Rust… :D To be honest, the author’s blog post convinced me a few years ago and I started using it. I might be happy if im would still be using the silver searcher though…

Final Thoughts

The Rust community is really productive and nice ideas are emerging. Personally, I don’t care if a tool is written in Rust, Perl, or Brainfuck as long as it solves a task and meets my requirements. That should be the message of this blogpost: “(Re)Written in Rust” is not a feature or a reason to use a tool. It is an implementation detail. Please, dear Rust community, write software which actually improves the status quo. There are great examples that actually do improve my workflow, like ripgrep (vs grep) and fd (vs find). These examples improve my workflow because they are well designed for me as a user. They do not improve my workflow because they are written in Rust.


  1. Taken from the homepage https://www.rust-lang.org/ ↩︎

  2. I mostly use Arch Linux, a bit Debian, and from time to time FreeBSD. I might even enforce POSIX variants of these tools, but it was not neccessary in the past. Here is a good reference about how to not publish software: https://drewdevault.com/2019/12/09/Developers-shouldnt-distribute.html ↩︎

  3. git is a good example, since they provide --porcelain flags for some commands to ensure their output will never change its structure. ↩︎