Description
The program atop is an interactive monitor to view the load on a Linux system. It shows the occupation of the most critical hardware resources (from a performance point of view) on system level, i.e. cpu, memory, disk and network.It also shows which processes are responsible for the indicated load with respect to cpu- and memory load on process level; disk- and network load is only shown per process if a kernel patch has been installed.
Every interval (default: 10 seconds) information is shown
about the resource occupation on system level (cpu, memory, disks and
network layers),
followed by a list of processes which have been active during the last
interval (note that all processes that were unchanged during the last
interval are not
shown, unless the key 'a' has been pressed). If the list of active
processes does not entirely fit on the screen, only the top of the list
is shown (sorted in
order of activity).
The intervals are repeated till the number of samples (specified
as command argument) is reached, or till the key 'q' is pressed in
interactive mode.
When atop is started, it checks whether the standard output channel is connected to a screen, or to a file/pipe. In the first case it produces screen control codes (via the curses library) and behaves interactively; in the second case it produces flat ASCII-output.
In interactive mode, the output of atop can be controlled
by pressing particular keys. However it is also possible to specify such
key as flag
on the command line. In the latter case atop will switch to the
indicated mode on beforehand; this mode can be modified again
interactively. Specifying
such key as flag is especially useful when running atop with
output to a pipe or file (non-interactively). The flags used are the
same as the keys which
can be pressed in interactive mode (see section INTERACTIVE COMMANDS).
Additional flags are available to support storage of atop-data in raw
format (see section RAW DATA STORAGE).
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