Add System.find_executable!/1

lib/elixir/lib/port.ex

@@ -124,9 +124,9 @@ defmodule Port do
 
   Spawn executable is a more restricted and explicit version of spawn. It expects
   full file paths to the executable you want to execute. If they are in your `$PATH`,
-  they can be retrieved by calling `System.find_executable/1`:
+  they can be retrieved by calling `System.find_executable!/1`:
 
-      iex> path = System.find_executable("echo")
+      iex> path = System.find_executable!("echo")
       iex> port = Port.open({:spawn_executable, path}, [:binary, args: ["hello world"]])
       iex> flush()
       {#Port<0.1380>, {:data, "hello world\n"}}

lib/elixir/lib/system.ex

@@ -630,8 +630,19 @@ defmodule System do
   operating systems. It also considers the proper executable
   extension for each operating system, so for Windows it will try to
   lookup files with `.com`, `.cmd` or similar extensions.
+
+  See also `find_executable!/1`.
+
+  ## Examples
+
+      System.find_executable("bash")
+      #=> "/bin/bash"
+
+      System.find_executable("unknown")
+      #=> nil
+
   """
-  @spec find_executable(binary) :: binary | nil
+  @spec find_executable(binary()) :: binary() | nil
   def find_executable(program) when is_binary(program) do
     assert_no_null_byte!(program, "System.find_executable/1")
 
@@ -641,6 +652,27 @@ defmodule System do
     end
   end
 
+  @doc """
+  Locates an executable on the system or raises an error.
+
+  See also `find_executable/1`.
+
+  ## Examples
+
+      System.find_executable!("bash")
+      #=> "/bin/bash"
+
+      System.find_executable!("unknown")
+      ** (RuntimeError) could not find executable "unknown" in PATH
+
+  """
+  @doc since: "1.20.0"
+  @spec find_executable!(binary()) :: binary()
+  def find_executable!(program) when is_binary(program) do
+    find_executable(program) ||
+      raise "could not find executable #{inspect(program)} in PATH"
+  end
+
   @doc """
   Returns all system environment variables.
 

lib/elixir/test/elixir/system_test.exs

@@ -126,7 +126,7 @@ defmodule SystemTest do
     test "cmd/3 with absolute and relative paths", config do
       echo = Path.join(config.tmp_dir, @echo)
       File.mkdir_p!(Path.dirname(echo))
-      File.ln_s!(System.find_executable("cmd"), echo)
+      File.ln_s!(System.find_executable!("cmd"), echo)
 
       File.cd!(Path.dirname(echo), fn ->
         # There is a bug in OTP where find_executable is finding
@@ -210,7 +210,7 @@ defmodule SystemTest do
     test "cmd/3 with absolute and relative paths", config do
       echo = Path.join(config.tmp_dir, @echo)
       File.mkdir_p!(Path.dirname(echo))
-      File.ln_s!(System.find_executable("echo"), echo)
+      File.ln_s!(System.find_executable!("echo"), echo)
 
       File.cd!(Path.dirname(echo), fn ->
         # There is a bug in OTP where find_executable is finding