A man sent to prison more than a dozen times is starting yet another period behind bars.

Ryan Rainey pleaded guilty at Dumbarton Sheriff Court on October 1 to having possession of a knife in the town centre earlier this year.

The 36-year-old was said to accept the court had no other option but to be jailed yet again.

Listed in court papers as a prisoner in Greenock, he appeared from custody and admitted to having the knife on May 27 at Strathleven Place, Dumbarton. He was on bail at the time from the Sheriff Appeal Court.

The Crown accepted a not-guilty plea to shouting, swearing and uttering threats of violence on the same date.

The fiscal depute told the court that around 10.30am that morning, police attended the Argos in Dumbarton after reports of a male who appeared disorientated.

Staff said they didn't want to make a complaint but were concerned for his wellbeing.

Officers found him under the influence of drugs and a search revealed a Stanley craft knife from his pocket.

Rainey's defence solicitor said her client was there to get items for his home and was using the blade for cutting lino.

"Other than that there's nothing else to say," she said.

Sheriff Maxwell Hendry said the man had been sentenced to prison 14 times by his calculation, and twice had supervised release.

"And the offending just carries on," he said. "Does he accept there's nothing more the court can do?"

The defence solicitor replied: "Yes my lord."

Sheriff Hendry, noting Rainey was only in his mid-30s, told him to just keep behaving as he has "if you want life to carry on as it has for quite some time".

He said the court had tried to help him but jail was the only option. He sentenced him to 12 months, backdated to May 28.