FEATURE: Stream stdout when running commands

CHANGELOG

@@ -1,3 +1,7 @@
+1.4.0 - 01-07-2026
+
+- Stream command output directly to stdout instead of buffering
+
 1.3.0 - 07-08-2025
 
 - Add --params option

lib/pups/exec_command.rb

@@ -111,17 +111,24 @@ def spawn(command)
         return pid
       end
 
-      IO.popen(command, "w+") do |f|
-        if stdin
-          # need a way to get stdout without blocking
-          Pups.log.info(stdin)
-          f.write stdin
-          f.close
-        else
-          Pups.log.info(f.readlines.join)
-        end
+      opts = { out: $stdout, err: $stderr }
+
+      if stdin
+        reader, writer = IO.pipe
+        opts[:in] = reader
+      end
+
+      pid = Process.spawn(command, opts)
+
+      if stdin
+        reader.close
+        Pups.log.info(stdin)
+        writer.write(stdin)
+        writer.close
       end
 
+      Process.wait(pid)
+
       unless $CHILD_STATUS == 0
         err =
           Pups::ExecError.new(

lib/pups/version.rb

@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module Pups
-  VERSION = "1.3.0"
+  VERSION = "1.4.0"
 end

test/exec_command_test.rb

@@ -98,5 +98,44 @@ def test_can_terminate_rogues
 
       assert_raises(Errno::ECHILD) { Process.waitpid(pid, Process::WNOHANG) }
     end
+
+    def test_stdout_streaming
+      # Starts a long-running process that outputs immediately
+      # and then watches a file before quitting.
+      # If stdout is properly streamed, we should see the output
+      # immediately rather than waiting for the process to end.
+
+      signal_file = Tempfile.new("signal")
+      signal_path = signal_file.path
+      signal_file.close
+
+      reader, writer = IO.pipe
+      original_stdout = $stdout.dup
+
+      $stdout.reopen(writer)
+
+      cmd = ExecCommand.new({})
+      cmd.add("echo 'streamed output'; while [ ! -s #{signal_path} ]; do sleep 0.1; done")
+
+      thread = Thread.new { cmd.run }
+
+      # Wait for output - if streaming works, it appears immediately
+      # If buffered, it would never appear since command loops until signaled
+      ready = IO.select([reader], nil, nil, 2)
+      assert ready, "Output should be available before command completes"
+
+      output = reader.read_nonblock(1000)
+      assert_includes(output, "streamed output")
+    ensure
+      $stdout.reopen(original_stdout) if original_stdout
+
+      writer&.close
+      reader&.close
+
+      File.write(signal_path, "done")
+      signal_file&.unlink
+
+      thread.join(2)
+    end
   end
 end