ionice:tldr:afdf5

The command ionice is used in Linux systems to prioritize the input/output (I/O) scheduling of a process or command. It allows you to control the I/O priority and class of a specified command.

Here is a breakdown of the command you provided:

1. ionice: This is the command itself.

2. -c ${scheduling_class}: This option sets the scheduling class for the command. The ${scheduling_class} is a placeholder for a value that specifies the scheduling class to use. There are three possible values for ${scheduling_class}:

   a. 0 (Default): Indicates none. The command will be run with the default scheduling class.

   b. 1 (Real-time): Indicates real-time scheduling class. This class provides the highest priority and is suited for time-critical tasks.

   c. 2 (Best-effort): Indicates best-effort scheduling class. This is the default class for most processes.

3. -n ${priority}: This option sets the I/O priority for the command. The ${priority} is a placeholder for a value that specifies the priority. The priority values range from 0 (highest) to 7 (lowest).

4. ${command}: This is a placeholder for the actual command you want to run or execute with the specified I/O scheduling and priority.

In summary, the ionice command is used to control the I/O priority and scheduling class of a given command, allowing you to prioritize or adjust its disk I/O operations.