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Linux Pocket Guide, 2nd Edition by Daniel J. Barrett

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Name

top — stdin  stdout  - file  -- opt  --help  --version

Synopsis

top [options]

The top command lets you monitor the most active processes, updating the display at regular intervals (say, every second). It is a screen-based program that updates the display in place, interactively.

$ top
94 processes: 81 sleeping, 1 running, 0 zombie, 11 stopped
CPU states: 1.1% user, 0.5% system, 0.0% nice, 4.5% idle
Mem: 523812K av, 502328K used, 21484K free, 0K shrd, ...
Swap:  530104K av,  0K used, 530104K free  115300K cached

PID   USER PRI NI SIZE SHARE STAT %CPU %MEM TIME COMMAND
26265 smith 10 0  1092  840  R    4.7  0.2  0:00 top
    1 root   0 0   540  472  S    0.0  0.1  0:07 init
    2 root   0 0     0    0  SW   0.0  0.0  0:00 kflushd
...

While top is running, you can press keys to change its behavior, such as setting the update speed (s), hiding idle processes (i), or killing processes (k). Type h to see a complete list and q to quit.

Useful options

-nN

Perform N updates, then quit.

-dN

Update the display every N seconds.

-pN -pM ...

Display only the processes with PID N, M, ..., up to 20 processes.

-c

Display the command-line arguments of processes.

-b

Print on standard output noninteractively, without playing screen tricks. top -b -n1 > outfile saves a quick snapshot to a file.

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