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Created March 30, 2026 15:50
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Generating a 10-bit id from a machine-id
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machine_id_1024.md

NextCloud v33 requests that a "serverid" is set in the configuration - this is an integer between 0 and 1023 (ie 10-bit).

I looked at generating a stable value based on machine-id, with the hope that there would be no clash for a small number of servers.

sha256sum /etc/machine-id | head -c4 | od -An -tu2 | tr -d ' ' | awk '{print int($1) % 1024}'
  • get the first 4 hex characters from the sha256sum of the machine-id - although the SHAing is probably redundant
  • convert the input into 2 unsigned decimals, and truncate their representations into one value
  • use awk int() to render that value as a 10-bit number
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