diff --git a/metropolis/pkg/cmd/BUILD.bazel b/metropolis/pkg/cmd/BUILD.bazel
new file mode 100644
index 0000000..7d5bbeb
--- /dev/null
+++ b/metropolis/pkg/cmd/BUILD.bazel
@@ -0,0 +1,11 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
+
+go_library(
+    name = "cmd",
+    srcs = ["run.go"],
+    importpath = "source.monogon.dev/metropolis/pkg/cmd",
+    visibility = ["//visibility:public"],
+    deps = [
+        "//metropolis/pkg/logbuffer",
+    ],
+)
diff --git a/metropolis/pkg/cmd/run.go b/metropolis/pkg/cmd/run.go
new file mode 100644
index 0000000..d5690a1
--- /dev/null
+++ b/metropolis/pkg/cmd/run.go
@@ -0,0 +1,66 @@
+// Package cmd contains helpers that abstract away the chore of starting new
+// processes, tracking their lifetime, inspecting their output, etc.
+package cmd
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"os"
+	"os/exec"
+	"strings"
+
+	"source.monogon.dev/metropolis/pkg/logbuffer"
+)
+
+// RunCommand starts a new process and waits until either its completion, or
+// appearance of expectedOutput in any line emitted by it. It returns true, if
+// expectedOutput was found, and false otherwise.
+//
+// The process will be killed both in the event the context is cancelled, and
+// when expectedOutput is found.
+func RunCommand(ctx context.Context, path string, args []string, expectedOutput string) (bool, error) {
+	// Make a sub-context to ensure the process exits when this function is done.
+	ctx, ctxC := context.WithCancel(ctx)
+	defer ctxC()
+
+	// Copy the stdout and stderr output to a single channel of lines so that they
+	// can then be matched against expectedOutput.
+
+	// Since LineBuffer can write its buffered contents on a deferred Close,
+	// after the reader loop is broken, avoid deadlocks by making lineC a
+	// buffered channel.
+	lineC := make(chan string, 2)
+	outBuffer := logbuffer.NewLineBuffer(1024, func(l *logbuffer.Line) {
+		lineC <- l.Data
+	})
+	defer outBuffer.Close()
+	errBuffer := logbuffer.NewLineBuffer(1024, func(l *logbuffer.Line) {
+		lineC <- l.Data
+	})
+	defer errBuffer.Close()
+
+	// Prepare the command context, and start the process.
+	cmd := exec.CommandContext(ctx, path, args...)
+	// Tee std{out,err} into the linebuffers above and the process' std{out,err}, to
+	// allow easier debugging.
+	cmd.Stdout = io.MultiWriter(os.Stdout, outBuffer)
+	cmd.Stderr = io.MultiWriter(os.Stderr, errBuffer)
+	if err := cmd.Start(); err != nil {
+		return false, fmt.Errorf("couldn't start the process: %w", err)
+	}
+
+	// Try matching against expectedOutput and return the result.
+	for {
+		select {
+		case <-ctx.Done():
+			return false, ctx.Err()
+		case line := <-lineC:
+			if strings.Contains(line, expectedOutput) {
+				cmd.Process.Kill()
+				cmd.Wait()
+				return true, nil
+			}
+		}
+	}
+}