Last June, Cody Brooks grabbed the victim from behind in a shared space in the prison and tried to stab him in the throat, but the victim moved his head and the weapon instead grazed his forehead.

Brooks continued to stab at the victim's back, which led to the victim suffering a wound measuring one centimetre by one centimetre.

More court news: Child homicide case against mother and her partner dropped

About 40 prisoners and three staff members were in the room at time, and police prosecutor Leading Senior Constable Mick Arnott told the Bendigo Magistrates' Court that Brooks' actions caused fear and concern.

Brooks told police he had had the knife for about one month and had been sharpening it.

Brooks pleaded guilty on Thursday to intentionally causing injury and being armed with a controlled weapon with criminal intent in relation to the incident.

He told police the victim had been stealing from other inmates' cells, but his defence lawyer Nicholas Rolfe said his client instructed him the victim had threatened him with sexual violence and death.

Brooks also pleaded guilty to theft and intentionally damaging property for unrelated incidents.

More court news: Man avoids jail after shoplifting designer shirt

On February 25 last year, Brooks entered a sports goods shop in Kangaroo Flat, picked up two pairs of tracksuit pants and two jackets worth just under $340, and fled.

Then last December, while in custody in a different prison, Brooks smashed his cell toilet beyond repair when he was locked in his cell after an incident.

He also used pieces of the toilet to smash the cell observation window, but calmed down after staff spoke to him.

The court heard it cost $3000 to repair the damage.

Brooks is currently in prison for up to four years and two months, for an aggravated carjacking.

More court news: ATM thieves were 'out of control'

Mr Rolfe said the stabbing incident warranted a term of imprisonment, but it should be served concurrently with his present sentence.

Brooks was eligible for parole after three years, but Mr Rolfe said his client - who was originally from South Australia - had no friends or family in Victoria and therefore nowhere to go upon release, so it was unlikely he would be paroled.

He said Brooks suffered "considerable trauma and deprivation" as a child, including exposure to family violence and drug use.

Brooks' mental health and substance abuse issues meant imprisonment would be harder for him than others, Mr Rolfe said.

Leading Senior Constable Arnott submitted that Brooks' crime in prison fell under legislation that made a cumulative sentence mandatory unless there were exceptional circumstances.

However, magistrate Julie Grainger said she believed this law did not apply to this type of offending.

Ms Grainger adjourned Brooks' sentencing until September 11, to determine whether this legislation would apply.

Have you signed up to the Bendigo Advertiser's daily newsletter and breaking news emails? You can register below and make sure you are up to date with everything that's happening in central Victoria.