Use top command to monitor process status in Linux

Typical operations

General

• s: set the update interval
• W: Save the option

Task list manipulation

• u: Filter the task list by user name

• o: Filter the task list by entering an expression, such as

  COMMAND=...
  %MEM>10
  

• =: Clear the filter for the task list
• f: Customize the columns

Visualization effect

• z: toggle color and mono mode
• x: highlight the sort field, i.e. the whole corresponding column will be highlighted.
• y: highlight running tasks
• b: reverse the highlighting effect for the sorting field and running tasks

Clarification of the time since program start

• TIMES+: Total CPU time the task has used since it started. It has the granularity of hundredth of a second, i.e. its accuracy is 1/100 second. Its display format is, for example, 6000:25.03, which means 6000 minutes, 25 seconds and 3 hundredths second. Also note that this is the total CPU time. If the process runs in n threads, the actual program execution time is about TIMES+/n.
• TIMES: same as TIMES+ but with second accuracy.

N.B. The time in top is the CPU time not the elapsed time. To get the latter, ps command with the option etime should be used instead (reference). The returned result has the date and time format Days-Hours:Minutes:Seconds.

ps -p 12698 -o etime

   ELAPSED
2-03:50:03