Which command is used to start a command or script with a higher priority level?

The command that is used to start a command or script with a higher priority level is nice. The nice command allows users to launch processes with a specified "niceness" value, which determines their scheduling priority. By default, processes run with a niceness value of 0. If you want to start a command with a higher priority (which means a lower niceness value), you can use the nice command followed by a negative niceness value—like this: nice -n -10 command. This increases the priority of the command when scheduled by the system.

Understanding the concept of niceness is crucial because it affects how the CPU allocates time to processes. Lower niceness values mean higher priority, allowing the process to get more CPU time compared to others with higher niceness values. This is particularly useful in resource-intensive applications where efficient CPU usage is critical.

The other commands, while related to process management, serve different purposes. Renice is used to alter the priority of an already running process, start is not a valid command for managing process priorities, and priority does not exist as a standalone command in Linux. This distinction makes nice the appropriate choice for starting a new process with altered priority levels.