diff --git a/local/pkgs/biu/include/biu/common.hpp b/local/pkgs/biu/include/biu/common.hpp
index a882dbf4..64462c58 100644
--- a/local/pkgs/biu/include/biu/common.hpp
+++ b/local/pkgs/biu/include/biu/common.hpp
@@ -22,6 +22,8 @@ namespace biu
     using int128_t = __int128_t;
     using uint128_t = __uint128_t;
 
+    struct Empty {};
+
     struct CaseInsensitiveStringLessComparator
     {
       template <typename String> constexpr bool operator()(const String& s1, const String& s2) const;
@@ -64,11 +66,31 @@ namespace biu
     template <typename T, typename Fallback = void> using FallbackIfNoTypeDeclared
       = typename detail_::FallbackIfNoTypeDeclaredHelper<T, Fallback>::Type;
 
-    namespace detail_ { struct ExecResult { int exit_code; std::string stdout, stderr; }; }
-    detail_::ExecResult exec
+    namespace detail_
+    {
+      template <bool DirectStdout, bool DirectStderr> struct ExecResult
+      {
+        int exit_code;
+        std::conditional_t<DirectStdout, Empty, std::string> stdout;
+        std::conditional_t<DirectStderr, Empty, std::string> stderr;
+      };
+      template <bool DirectStdin, bool DirectStdout, bool DirectStderr>
+        detail_::ExecResult<DirectStdout, DirectStderr> exec
+      (
+        std::filesystem::path program, std::vector<std::string> args, std::optional<std::string> stdin,
+        std::map<std::string, std::string> extra_env
+      );
+    }
+    template <bool DirectStdin = false, bool DirectStdout = false, bool DirectStderr = false> requires (!DirectStdin)
+      detail_::ExecResult<DirectStdout, DirectStderr> exec
     (
-      std::filesystem::path program, std::vector<std::string> args, std::optional<std::string> stdin,
-      std::map<std::string, std::string> extra_env
+      std::filesystem::path program, std::vector<std::string> args, std::optional<std::string> stdin = {},
+      std::map<std::string, std::string> extra_env = {}
+    );
+    template <bool DirectStdin = false, bool DirectStdout = false, bool DirectStderr = false> requires DirectStdin
+      detail_::ExecResult<DirectStdout, DirectStderr> exec
+    (
+      std::filesystem::path program, std::vector<std::string> args, std::map<std::string, std::string> extra_env = {}
     );
   }
 }
diff --git a/local/pkgs/biu/include/biu/common.tpp b/local/pkgs/biu/include/biu/common.tpp
index c664d151..d9df6c8d 100644
--- a/local/pkgs/biu/include/biu/common.tpp
+++ b/local/pkgs/biu/include/biu/common.tpp
@@ -1,6 +1,7 @@
 # pragma once
 # include <boost/functional/hash.hpp>
 # include <biu/common.hpp>
+# include <boost/process.hpp>
 
 namespace biu::common
 {
@@ -21,4 +22,56 @@ namespace biu::common
       [](char c1, char c2){return std::tolower(c1) < std::tolower(c2);}
     );
   }
-}
\ No newline at end of file
+  template <bool directStdin, bool directStdout, bool directStderr> detail_::ExecResult<directStdout, directStderr> exec
+  (
+    std::filesystem::path program, std::vector<std::string> args, std::optional<std::string> stdin,
+    std::map<std::string, std::string> extra_env
+  )
+  {
+    namespace bp = boost::process;
+    bp::ipstream stdout_stream, stderr_stream;
+    bp::opstream input_stream;
+    auto&& stdout =
+      [&]{ if constexpr (directStdout) return bp::std_out > ::stdout; else return bp::std_out > stdout_stream; }();
+    auto&& stderr =
+      [&]{ if constexpr (directStderr) return bp::std_err > ::stderr; else return bp::std_err > stderr_stream; }();
+    auto&& input = [&]
+    {
+      if constexpr (directStdin) return bp::std_in < ::stdin;
+      else if (stdin) return bp::std_in < input_stream; else return bp::std_in < bp::null;
+    }();
+    std::unique_ptr<bp::child> process;
+    bp::environment env = boost::this_process::environment();
+    for (const auto& [key, value] : extra_env) env[key] = value;
+    process = std::make_unique<bp::child>(program.string(), bp::args(args), stdout, stderr, input, env);
+    if (stdin) { input << *stdin; input.pipe().close(); }
+    process->wait();
+    return
+    {
+      process->exit_code(),
+      [&]
+      {
+        if constexpr (directStdout) return std::string{std::istreambuf_iterator<char>{stdout.rdbuf()}, {}};
+        else return Empty{};
+      }(),
+      [&]
+      {
+        if constexpr (directStderr) return std::string{std::istreambuf_iterator<char>{stderr.rdbuf()}, {}};
+        else return Empty{};
+      }()
+    };
+  }
+  template <bool DirectStdin, bool DirectStdout, bool DirectStderr> requires (!DirectStdin)
+    detail_::ExecResult<DirectStdout, DirectStderr> exec
+  (
+    std::filesystem::path program, std::vector<std::string> args, std::optional<std::string> stdin,
+    std::map<std::string, std::string> extra_env
+  )
+    { return exec<DirectStdout, DirectStderr>(program, args, stdin, extra_env); }
+  template <bool DirectStdin, bool DirectStdout, bool DirectStderr> requires DirectStdin
+    detail_::ExecResult<DirectStdout, DirectStderr> exec
+  (
+    std::filesystem::path program, std::vector<std::string> args, std::map<std::string, std::string> extra_env
+  )
+    { return exec<DirectStdin, DirectStdout, DirectStderr>(program, args, {}, extra_env); }
+}
diff --git a/local/pkgs/biu/src/common.cpp b/local/pkgs/biu/src/common.cpp
index d9904c19..b0de6c8f 100644
--- a/local/pkgs/biu/src/common.cpp
+++ b/local/pkgs/biu/src/common.cpp
@@ -1,45 +1,9 @@
 # include <future>
 # include <utility>
 # include <biu.hpp>
-# include <boost/process.hpp>
 
 namespace biu
 {
   std::regex literals::operator""_re(const char* str, std::size_t len) { return std::regex{str, len}; }
-  namespace common
-  {
-    void block_forever() { std::promise<void>().get_future().wait(); std::unreachable(); }
-    detail_::ExecResult exec
-    (
-      std::filesystem::path program, std::vector<std::string> args, std::optional<std::string> stdin,
-      std::map<std::string, std::string> extra_env
-    )
-    {
-      namespace bp = boost::process;
-      bp::ipstream stdout, stderr;
-      bp::opstream input;
-      std::unique_ptr<bp::child> process;
-      bp::environment env = boost::this_process::environment();
-      for (const auto& [key, value] : extra_env) env[key] = value;
-      if (stdin)
-      {
-        process = std::make_unique<bp::child>
-          (program.string(), bp::args(args), bp::std_out > stdout, bp::std_err > stderr,
-            bp::std_in < input, env);
-        input << *stdin;
-        input.pipe().close();
-      }
-      else process = std::make_unique<bp::child>
-        (program.string(), bp::args(args), bp::std_out > stdout, bp::std_err > stderr,
-          bp::std_in < bp::null, env);
-      process->wait();
-      return
-      {
-        process->exit_code(),
-        std::string{std::istreambuf_iterator<char>{stdout.rdbuf()}, {}},
-        std::string{std::istreambuf_iterator<char>{stderr.rdbuf()}, {}}
-      };
-    }
-  }
-
+  namespace common { void block_forever() { std::promise<void>().get_future().wait(); std::unreachable(); } }
 }