# purefetch: a fastfetch-style system info tool in Rust with zero dependencies

> Source: <https://dev.to/ooonea/purefetch-a-fastfetch-style-system-info-tool-in-rust-with-zero-dependencies-19f0>
> Published: 2026-07-04 15:45:04+00:00

I like `neofetch`

/ `fastfetch`

, but I wanted one with a genuinely *empty*

dependency graph — nothing pulled from crates.io. So I built **purefetch**: a small

system-info fetcher written entirely in Rust using only `std`

plus raw Linux

syscalls.

Disclosure up front:purefetch was built largely withAI assistance

(Claude Code). I directed the design, and every change was reviewed and tested —

including running it on four architectures under QEMU — but most of the code is

AI-generated. I'd rather be honest about that than pretend otherwise.

```
       _,met$$$$$gg.          ooonea@unicorn
    ,g$$$$$$$$$$$$$$$P.       ──────────────
  ,g$$P"     """Y$$.".        OS        Debian GNU/Linux 13.5 (trixie) x86_64
 ,$$P'              `$$$.     Host      ThinkPad P53 (20QQS0JD01)
',$$P       ,ggs.     `$$b:   Kernel    6.12.94+deb13-amd64
`d$$'     ,$P"'   .    $$$    Uptime    6 days, 15 hours, 30 mins
 $$P      d$'     ,    $$P    Packages  2477 (dpkg), 1 (flatpak)
 $$:      $$.   -    ,d$$'    Shell     zsh 5.9
 $$;      Y$b._   _,d$P'      Display   1920x1080 (eDP-1)
 Y$$.    `.`"Y$$$$P"'         DE        GNOME 48.7
 `$$b      "-.__              WM        Mutter (Wayland)
  `Y$$                        Terminal  kitty 0.41.1
   `Y$$.                      CPU       Intel(R) Core(TM) i7-9850H @ 4.60 GHz
     `$$b.                    GPU       Quadro RTX 3000
       `Y$$b.                 Memory    15.28 GiB / 62.61 GiB (24%)
          `"Y$b._             Swap      0 B / 8.00 GiB (0%)
              `"""            Disk (/)  8.52 GiB / 489.57 GiB (2%)
                              Locale    en_US.UTF-8
                              Battery   76% (Not charging)
```

No `libc`

crate, no `sysinfo`

, no `nix`

, no color crate — nothing from crates.io.

Almost everything is just reading and parsing `/proc`

and `/sys`

. The result is a

single **~484 KiB** binary that builds offline.

The only things `std`

can't do are `statfs`

(disk usage) and `ioctl`

(terminal size

/ tty check). Instead of pulling in a binding crate, those are issued as **raw Linux
syscalls** via

`core::arch::asm!`

:

```
#[cfg(target_arch = "x86_64")]
unsafe fn syscall3(n: usize, a1: usize, a2: usize, a3: usize) -> isize {
    let ret: isize;
    core::arch::asm!(
        "syscall",
        inlateout("rax") n as isize => ret,
        in("rdi") a1, in("rsi") a2, in("rdx") a3,
        out("rcx") _, out("r11") _,
        options(nostack),
    );
    ret
}
```

Each architecture gets its own `syscall3`

(a different instruction and register

convention) plus its syscall numbers. aarch64, riscv64 and loongarch64 share the

"asm-generic" table (`statfs = 43`

, `ioctl = 29`

); x86_64 has its own.

I validated all four **end-to-end under qemu-user** — cross-compiling to each

On ZFS-on-root, a naive `MemTotal - MemAvailable`

massively over-reports used RAM,

because the ZFS ARC is kernel-slab cache that `MemAvailable`

doesn't count as

reclaimable. purefetch subtracts the reclaimable ARC (`arcstats size - c_min`

),

which lines up with what `fastfetch`

and ZFS-aware `htop`

show. On my box that's the

difference between "37 GiB used" (wrong) and "15 GiB used" (right).

The 24 distro logos live as plain text in `assets/logos/*.txt`

, and a small Python

script generates `src/logo.rs`

. Adding a logo is one text file plus a regen.

It also taught me a lesson. An early version of the generator emitted the color as

`sgr: "215;7;81"`

instead of `"38;2;215;7;81"`

— dropping the truecolor prefix. The

terminal then read `\e[215;7;81m`

as "code 215 (ignored) + 7 (reverse video)", so

every logo rendered washed-out instead of its brand color. I missed it because my

render checks all ran with `--no-color`

. Fixed in 0.1.2 — a good reminder to test the

thing your users actually *see*.

```
cargo install purefetch
```

Source, issues and PRs: ** https://github.com/ooonea/purefetch** (MIT OR Apache-2.0).