Bash List Processes
top opens a continuously updating, interactive view of running processes and overall system load, making it the standard tool for live monitoring.
Launching top
Typing top and pressing enter takes over the terminal with a live display that refreshes every few seconds by default. The screen is split between a system-wide header and a scrolling table of the busiest processes, sorted by CPU usage unless you change it.
top Output
$ top
top - 10:32:01 up 4 days, 2:15, 2 users, load average: 0.42, 0.38, 0.31
Tasks: 148 total, 2 running, 145 sleeping, 0 stopped, 1 zombie
%Cpu(s): 6.3 us, 2.1 sy, 0.0 ni, 91.0 id, 0.4 wa
MiB Mem : 7854.0 total, 1204.3 free, 2938.1 used, 3711.6 buff/cache
PID USER PR NI VIRT RES %CPU %MEM TIME+ COMMAND
3305 alice 20 0 812340 65200 12.3 0.8 3:41.02 node
1188 root 20 0 55344 9100 0.3 0.1 0:02.10 nginxReading the Header
The load average shows three numbers: the average number of processes wanting CPU time over the last 1, 5, and 15 minutes. The Tasks line counts how many processes are running, sleeping, stopped, or zombied. The %Cpu(s) line breaks CPU time into user (us), system (sy), niced (ni), and idle (id) percentages, and the memory lines show how much RAM is free, used, and held in the disk cache.
Interactive Commands Inside top
top isn't just a display, it accepts single-key commands while it's running. Press P to sort by CPU usage, M to sort by memory usage, u to filter by a specific user, k to kill a process by PID, and q to quit back to your shell.
- P — sort the process list by %CPU (the default)
- M — sort the process list by %MEM
- u — prompt for a username and show only that user's processes
- k — prompt for a PID, then a signal number, and send it
- r — renice a process, changing its scheduling priority
- q — quit top and return to the shell
Killing From Inside top
$ top
(press k)
PID to signal/kill [default pid = 3305] 3305
Signal [default 15] 9
