Updated: 22 October 2026 · Applies to: the procps-ng top command, any Linux distribution
top shows a live view of load average, logged-in users, CPU and free memory, updating a few times a second.
top
The -d switch: change the update interval
-d sets the delay between updates, in the form ss.tt (seconds.tenths). For example, update every 5 seconds:
top -d 5.0
Output field reference
PID : Process ID
USER : The user running the process
PR : Priority
NI : Nice value
%CPU : CPU usage
TIME : CPU time used
%MEM : Memory usage (RES)
VIRT : Virtual image size (KB)
SWAP : Swapped size (KB)
RES : Resident size (KB)
S : Process status: D = uninterruptible sleep, R = running, S = sleeping,
T = traced or stopped, Z = zombie
Interactive keys while top is running
- Space: refresh the display immediately.
- h or ?: show the help page (q to leave it).
- k: kill a process; you are prompted for its PID.
- i: toggle hiding idle and zombie processes.
- Shift+I: toggle between Solaris mode (CPU percentage divided across all CPUs) and Irix mode (raw CPU time percentage); only affects multi-CPU systems.
- n or #: set how many processes to show; enter a number when prompted, or 0 to fill the screen (the default).
- q: quit.
- Shift+M: sort by resident memory usage.
- Shift+T: sort by time or cumulative time.
- c or Shift+P: sort by CPU usage (the default).
- Shift+A: sort by age, newest first.
- Shift+N: sort by PID, numerically.
