made with:

asciicast

Here are freeze-generated screenshots of the latest version:

Click to expand

just needs

needs --no-versions to skip version retrieval

needs -vvv to see what's going on

This logging output was hand crafted with (heavy) inspiration from charm/log building on env_logger. Ironically not because of the env-part of it, but because it feels like the simplest wrapper of std::log and it supports key-value-pairs which were very important to me. For now it will just reside inside of needs, but in the future I'm planning on moving it to it's own lib, maybe call it starlog...

cargo install needs

or

cargo binstall -y needs

or

# to disable version retrieval completely
cargo install needs --no-default-features

• timeouts for calling binaries
• more version matches
  • dates and major only (e.g. openjdk 24 2025-03-18)
  • dates with no seperator... (awk version 20200816👀)
• read-from-config-files feature (read ~/.cargo/.crates.toml directly for example)
• pipe-detection to make scripting easier
• version requirements via semver (e.g. needs gum>=0.14.*)
• more pretty output formats
  • center aligned
  • side-by-side (in boxes?)
• more parsable outptut formats
  • bash
  • json
  • toml
  • lua?

• integrate tests and screenshot generation with workflows
• better release workflow
• seperate out the logging part into a separate lib
• seperate crates.io README from the github one

Here's a detailed explanation of how needs works on deepwiki

And here's a flowchart of the process:

flowchart TD
    C(Discovery)
    E(Output)
    F(Exit)
    A(Start) --> B(Determine Binaries to check)
    B -->|*CLI Supply*| C
    B -->|*File Supply*| C
    B -->|*When None*| F
    C -->|*Found*| D(Version Retrieval)
    C -->|*Not Found*| E
    C -->|*When Quiet OR NoVersions*| F
    D --> E
    E --> F

This has been tested and shown good results, but there's always one that doesn't work with any conventions or just a really old program. In such cases the program doesn't return a version that needs can read, but instead goes off to do it's thing and potentionally ends up making modifications to your filesystem (e.g. deleting files for whatever-reason, we don't know yet).

If you happen to run into one, there's basically nothing I can do for you. Still, I would like to try or just hear about it so i can inlude it in a list to prevent future incidents.

The program is inspired by the has bash program. Therefore I also wanted it to have the version retrieval feature. For now that process relies on the individual binaries getting called with the --version flag, which can be extremely slow in some cases (the mintlify program for example takes almost an entire second to respond). Thanks to par_iter from rayon it's possible to run all commands in parallel tho, which helps at least a little bit.

For the future I want to improve the multithreading part by introducing a timeout for the threads. Those that take to long to answer will be terminated after the timeout and the affected binaries will only be marked as found, without a version.

But even with those improvements some might only want to check if the program is installed. Therefore I not only added a flag --no-versions but also made it a cargo feature which can be disabled with --no-default-features when installing.

Also planned is a feature that includes a list of known

• long running,
• uncomplying or old binaries which will not be called to retrieve their version.

To identify long running binaries, you can use the verbose flag to increase the logging level, which when reached TRACE (-vvvv) shows the timings for the individual binaries. If you also find poorly optimized programs, just create an issue so i can keep track of them, but you could also just notify the developer and tell him to stop using javascript for big terminal tools :)

As before mentioned, the speed of the program depends on the called binaries if run with version retrieval. The speed of the program itself is actually quite fast, see the report.md for the results of a benchmark. The benchmark was done with the hyperfine program, run on a M4 Macbook Pro.