Sar command in Linux, retrieving cpu, memory information

'sar' command in linux is a command to return CPU usage and memory usage information.

You can issue repeated option to keep it running returning the stats with specified times.

Ex: >sar 5 150

this will return the result every 5 seconds for 150 times.

some example out put is below:

21:00:56          CPU     %user     %nice   %system   %iowait    %steal     %idle
21:01:11          all         2.21        0.00      0.85          6.13          0.00         90.81
21:01:26          all         3.71        0.00      1.35          3.03          0.00         91.91
21:01:41          all         0.93        0.00      0.68          4.33          0.00         94.05
21:01:56          all         0.88        0.00      0.77          4.41          0.00         93.94
21:02:11          all         0.83        0.00      0.63          4.15          0.00         94.39
Average:          all       15.29        0.00      4.77        32.46          0.00         47.48

Here is what you can do to extract specific time interval from sar data file:

Sar puts its data in daily logs in /var/log/sa. So for instance, if you want to extract from /var/log/sa/sa16 file, use the –f option and then –s for start and –e for end in hh:mm:ss format:

> sar -f sa16 -s 19:00:01  -e 20:27:01

It will display to standard out and the last line is always the Average. If you need to span across two files, you can either append one to the other making a new file (watch for any extraneous lines for averages), or you can get data from each file and average them together. Hope this helps.