Is warm liquid better than cold for constipation? what is the best stool softener after hernia surgery?

Not clear but: Home remedy wise, it is often mentioned to try warm water with lemon juice. I haven't seen great data in this regards but it is out there and a classic part the morning ayurvedic tradition. Colace(docusate) is a classic commonly used softener. Best of luck.

Warm probably better: Senokot (senna) is effective as it combines a stool softener with a gentle laxative and is best used temporarily after surgery and then switching to simply a stool softener would be advisable.