The bg utility resumes suspended jobs from the current environment by running them as background jobs if job control is enabled. If the job specified by job_id is already a running background job, the bg utility will have no effect and shall exit successfully. Using bg to place a job into the background will cause its process ID to become "known in the current shell execution environment", as if it had been started as an asynchronous list.
Answer option D is incorrect. The fg utility continues a stopped job by running it in the foreground, some shells are not able to run this command.
Syntax:
fg [%job] Where %job specifies the job that a user wants to run in the foreground.
Answer option A is incorrect. The jobs command lists the jobs that are running in the background and in the foreground. If the prompt is returned with no information, no jobs are present.
Syntax: jobs [-p | -l] [-n] [-p] [-x] [job id]
Some important options used with jobs command are as follows:
Answer option C is incorrect. The top command is used to produce a frequently-updated list of processes. By default, the processes are ordered by percentage of CPU usage, with only the "top" CPU consumers shown. This command shows how much processing power and memory are being used, as well as other information about the running processes. The following figure demonstrates the output of the top command:
