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| -rw-r--r-- | doc/manual/src/language/builtin-constants.md | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/doc/manual/src/language/builtin-constants.md b/doc/manual/src/language/builtin-constants.md index c6bc9b74c..204daab6e 100644 --- a/doc/manual/src/language/builtin-constants.md +++ b/doc/manual/src/language/builtin-constants.md @@ -17,3 +17,26 @@ These constants are built into the Nix language evaluator: The built-in value `currentSystem` evaluates to the Nix platform identifier for the Nix installation on which the expression is being evaluated, such as `"i686-linux"` or `"x86_64-darwin"`. + +- [`builtins.currentTime`]{#builtins-currentTime} (integer) + + Return the [Unix time](https://en.wikipedia.org/wiki/Unix_time) at first evaluation. + Repeated references to that name will re-use the initially obtained value. + + Example: + + ```console + $ nix repl + Welcome to Nix 2.15.1 Type :? for help. + + nix-repl> builtins.currentTime + 1683705525 + + nix-repl> builtins.currentTime + 1683705525 + ``` + + > **Warning** + > + > This is intended for testing and debugging only. + > Do not use it in production systems, since an impure, that is, non-constant value will break reproducibility. |