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.
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,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).