The 28-year-old trader was taken by ambulance to Glasgow Royal Infirmary where he is still being treated for his injuries.
He is described as being in a serious but stable condition.
The incident took place at around 7.40am on Saturday at Suleman Newsagents in Kennedy Path in the Townhead area of Glasgow.
The shop is known for doubling as the newsagent's store in the BBC series Still Game.
The robber demanded money and threatened the shopkeeper with a weapon, then seriously assaulted him before running off with the small two-figure amount of cash and some cigarettes.
He was last seen running towards the area of St MungoAvenue.
The suspect is described as white, around 6ft in height and in his 30s.
He was wearing a black waterproof jacket with a hood, along with dark blue jeans with a white logo on the back, and white trainers.
Detective Constable David Hardie, of Police Scotland's Community Investigation Unit at Pollok, is appealing for anyone with any information to get in touch.
He said: "This was an unprovoked and particularly violent attack on an innocent member of the public who was simply doing his job. It is vital that we trace the man responsible.
"I would therefore urge anyone who saw this incident, or anyone who perhaps saw the suspect in the area at around the time of the robbery on Saturday morning, to get in touch."
Anyone with information that may help police is asked to contact 101, the non-emergency number for Police Scotland. Information can be given anonymously by calling Crimestoppers on 0800 555 111.