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Monitoring System Activity on the Command Line
Monitoring performance in Terminal can be useful for diagnosing performance issues, using the top and vm_stat tools (and iostat for disk I/O).
These tools are used in a top, which can be left running continually, refreshing the window at regular intervals.window. The most useful tool is
Show top 10 processes by CPU usage every 2 seconds, with data collected every 5 seconds:
top -o cpu -s 2 -i 5
Show top 10 processes by real memory every 2 seconds:
top -o rsize -s 2
The vm_stat tool also provides some useful statistics on the use of real memory, compressed memory and virtual memory.
The iostat tool also provides statistics on disk I/O.
Show up to 16 drives every 2 seconds:
iostat -w 2 -n 16