executil pipeline function

executil/pipeline.go

@@ -0,0 +1,45 @@
+package executil
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"os/exec"
+)
+
+func Pipeline(cmds ...*exec.Cmd) (output []byte, err error) {
+	var stdout io.ReadCloser
+
+	// build up stdin->stdout connections
+	for _, cmd := range cmds {
+		if stdout != nil {
+			cmd.Stdin = stdout
+		}
+
+		if stdout, err = cmd.StdoutPipe(); err != nil {
+			return nil, fmt.Errorf("failed to get stdout for %s: %s", cmd.String(), err)
+		}
+	}
+
+	// start commands
+	for _, cmd := range cmds {
+		if err = cmd.Start(); err != nil {
+			return nil, fmt.Errorf("failed to start cmd %s: %s", cmd.String(), err)
+		}
+	}
+
+	// read final output
+	if output, err = io.ReadAll(stdout); err != nil {
+		err = errors.Join(err, fmt.Errorf("failed to get pipeline tail stdout: %s", err))
+	}
+
+	// wait for commands to finish in reverse
+	for i := len(cmds) - 1; i > -1; i-- {
+		cmd := cmds[i]
+		if err := cmd.Wait(); err != nil {
+			return nil, fmt.Errorf("failed to wait for cmd %s: %s", cmd.String(), err)
+		}
+	}
+
+	return output, err
+}