stockholm/Zpkgs/krebs/genid.nix

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{ lib, pkgs, ... }:
pkgs.writeScriptBin "genid" ''
#! /bin/sh
# usage: genid NAME
set -euf
export PATH=${lib.makeSearchPath "bin" (with pkgs; [
bc
coreutils
])}
name=$1
hash=$(printf %s "$name" | sha1sum | cut -d\ -f1 | tr a-f A-F)
echo "
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min=2^24 # bigger than nobody and nogroup, see <nixos/modules/misc/ids.nix>
# and some spare for stuff like lxd.
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max=2^32 # see 2^(8*sizeof(uid_t))
ibase=16
($hash + min) % max
" | bc
''