Many UNIX tools return the memory consumtion for each process in kilobytes, pages and so on.

Composing a bit more complicated command using tools like awk, and grep can give you a column with numbers => meaning the number of kilobytes/pages for each process. In case you need to calculate the sum of all these numbers, here's how to do it:

Calculating the sum and average for a list of values 

where Sum is the sum of all the values on first column ($1), Avg is the average of these values and No is the number of values.

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