Special Exit Codes for Build Failure

doc/manual/source/command-ref/status-build-failure.md

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# Special exit codes for build failure

1xx status codes are used when requested builds failed.
The following codes are in use:

- `100` Generic build failure

  The builder process returned with a non-zero exit code.

- `101` Build timeout

  The build was aborted because it did not complete within the specified `timeout`.

- `102` Hash mismatch

  The build output was rejected because it does not match the
  [`outputHash` attribute of the derivation](@docroot@/language/advanced-attributes.md).

- `104` Not deterministic

  The build succeeded in check mode but the resulting output is not binary reproducible.

With the `--keep-going` flag it's possible for multiple failures to occur.
In this case the 1xx status codes are or combined using
[bitwise OR](https://en.wikipedia.org/wiki/Bitwise_operation#OR).

```
0b1100100
     ^^^^
     |||`- timeout
     ||`-- output hash mismatch
     |`--- build failure
     `---- not deterministic
```

Chunks

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Title: Special Exit Codes for Build Failure

Summary

This section describes the special exit codes (1xx) used when requested builds fail in Nix. Specific codes indicate generic build failures (100), timeouts (101), hash mismatches (102), and non-deterministic builds (104). The `--keep-going` flag allows multiple failures, and the resulting status code is a bitwise OR combination of the individual failure codes.