ExecStartPre

ExecStartPre is a directive used in systemd service unit files. It specifies commands that should be executed before the main ExecStart command is run. These commands are executed sequentially. If any ExecStartPre command fails (returns a non-zero exit code), the service unit will not be started, and subsequent ExecStartPre commands will not be executed. This directive is useful for performing setup tasks, such as creating directories, checking file permissions, or downloading necessary resources, before the main service process begins. It allows for robust service initialization by ensuring prerequisite conditions are met. Multiple ExecStartPre lines can be specified within a unit file, each representing a separate command to be executed in order.