top

Start top

$ top

$ top -i

$ top -u username

$ top -o %MEM

$ top -Hp process_id

$ top -p 1234,5678

$ top -b -n 1

top [-b] [-d delay] [-n iterations] [-p pid] [-u user] [-o field]

top provides a dynamic real-time view of a running system. It displays system summary information and a list of processes or threads currently being managed by the Linux kernel. The display is updated periodically and can be customized interactively.

-b, --batch

Run in batch mode (non-interactive), useful for piping output

Toggle between command line and program name display

Set the delay between screen updates

Scale task memory values (k/m/g/t/p)

Scale summary memory values (k/m/g/t/p/e)

Display individual threads instead of processes

Hide idle and zombie processes

Set maximum number of iterations before exit

Override the default sort field

Monitor only specified process IDs

Show only processes for specified effective user

Show processes for specified user (real, effective, saved, filesystem)

h or ?: Display help screen
q: Quit top
d or s: Change delay between updates
k: Kill a process
r: Renice a process
f: Manage displayed fields
o: Add filter expression
c: Toggle command line/program name
V: Toggle forest view mode
1: Toggle single/separate CPU states
m: Cycle memory display modes
t: Cycle CPU states display modes
R: Reverse sort order
< or >: Move sort column left/right
W: Write configuration file

D: Uninterruptible sleep
I: Idle kernel thread
R: Running
S: Sleeping (interruptible)
T: Stopped by job control signal
t: Stopped by debugger
Z: Zombie

The configuration file is saved to ~/.config/procps/toprc. Running in batch mode (-b) is recommended for scripting as it disables interactive features and produces parseable output.

top was originally written by Roger Binns and has been part of the procps (now procps-ng) package. It has been a standard system monitoring tool on Unix-like systems since the 1980s.

htop(1), atop(1), ps(1), free(1), uptime(1)