pkgs.writeShellApplication

The following is the current implementation of this function.

writeShellApplication =
    {
      /**
        The name of the script to write.

        # Type

        ```
        String
        ```
      */
      name,
      /**
        The shell script's text, not including a shebang.

        # Type

        ```
        String
        ```
      */
      text,
      /**
        Inputs to add to the shell script's `$PATH` at runtime.

        # Type

        ```
        [String|Derivation]
        ```
      */
      runtimeInputs ? [ ],
      /**
        Extra environment variables to set at runtime.

        # Type

        ```
        AttrSet
        ```
      */
      runtimeEnv ? null,
      /**
        `stdenv.mkDerivation`'s `meta` argument.

        # Type

        ```
        AttrSet
        ```
      */
      meta ? { },
      /**
        `stdenv.mkDerivation`'s `passthru` argument.

        # Type

        ```
        AttrSet
        ```
      */
      passthru ? { },
      /**
        The `checkPhase` to run. Defaults to `shellcheck` on supported
        platforms and `bash -n`.

        The script path will be given as `$target` in the `checkPhase`.

        # Type

        ```
        String
        ```
      */
      checkPhase ? null,
      /**
        Checks to exclude when running `shellcheck`, e.g. `[ "SC2016" ]`.

        See <https://www.shellcheck.net/wiki/> for a list of checks.

        # Type

        ```
        [String]
        ```
      */
      excludeShellChecks ? [ ],
      /**
        Extra command-line flags to pass to ShellCheck.

        # Type

        ```
        [String]
        ```
      */
      extraShellCheckFlags ? [ ],
      /**
        Bash options to activate with `set -o` at the start of the script.

        Defaults to `[ "errexit" "nounset" "pipefail" ]`.

        # Type

        ```
        [String]
        ```
      */
      bashOptions ? [
        "errexit"
        "nounset"
        "pipefail"
      ],
      /**
        Extra arguments to pass to `stdenv.mkDerivation`.

        :::note{.caution}
        Certain derivation attributes are used internally,
        overriding those could cause problems.
        :::

        # Type

        ```
        AttrSet
        ```
      */
      derivationArgs ? { },
      /**
        Whether to inherit the current `$PATH` in the script.

        # Type

        ```
        Bool
        ```
      */
      inheritPath ? true,
    }:
    writeTextFile {
      inherit
        name
        meta
        passthru
        derivationArgs
        ;
      executable = true;
      destination = "/bin/${name}";
      allowSubstitutes = true;
      preferLocalBuild = false;
      text =
        ''
          #!${runtimeShell}
          ${lib.concatMapStringsSep "\n" (option: "set -o ${option}") bashOptions}
        ''
        + lib.optionalString (runtimeEnv != null) (
          lib.concatStrings (
            lib.mapAttrsToList (name: value: ''
              ${lib.toShellVar name value}
              export ${name}
            '') runtimeEnv
          )
        )
        + lib.optionalString (runtimeInputs != [ ]) ''

          export PATH="${lib.makeBinPath runtimeInputs}${lib.optionalString inheritPath ":$PATH"}"
        ''
        + ''

          ${text}
        '';

      checkPhase =
        # GHC (=> shellcheck) isn't supported on some platforms (such as risc-v)
        # but we still want to use writeShellApplication on those platforms
        let
          shellcheckSupported =
            lib.meta.availableOn stdenv.buildPlatform shellcheck-minimal.compiler
            && (builtins.tryEval shellcheck-minimal.compiler.outPath).success;
          excludeFlags = lib.optionals (excludeShellChecks != [ ]) [
            "--exclude"
            (lib.concatStringsSep "," excludeShellChecks)
          ];
          shellcheckCommand = lib.optionalString shellcheckSupported ''
            # use shellcheck which does not include docs
            # pandoc takes long to build and documentation isn't needed for just running the cli
            ${lib.getExe shellcheck-minimal} ${
              lib.escapeShellArgs (excludeFlags ++ extraShellCheckFlags)
            } "$target"
          '';
        in
        if checkPhase == null then
          ''
            runHook preCheck
            ${stdenv.shellDryRun} "$target"
            ${shellcheckCommand}
            runHook postCheck
          ''
        else
          checkPhase;
    };