pkgs.replaceVars

replaceVars is a wrapper around the bash function substitute in the stdenv. It allows for terse replacement of names in the specified path, while checking for common mistakes such as naming a replacement that does nothing or forgetting a variable which needs to be replaced.

As with the --subst-var-by flag, names are encoded as @name@ in the provided file at the provided path.

Any unmatched variable names in the file at the provided path will cause a build failure.

Any remaining text that matches @[A-Za-z_][0-9A-Za-z_'-]@ in the output after replacement has occurred will cause a build failure.

Inputs

path (Store Path String)

The file in which to replace variables.

attrs (AttrsOf String)

Each entry in this set corresponds to a --subst-var-by entry in substitute.

Example

{ replaceVars }:

replaceVars ./greeting.txt { world = "hello"; }

See ../../test/replace-vars/default.nix for tests of this function.

Noogle also knows