Following on from my previous post about how to check how many apache processes are running - I recently wanted to find out exactly how much memory my applications where using… So I did a little research and found a few new and useful commands!

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ps haxo 'size' | (tr '\n' +; echo 0) | bc

You will recognise the `ps`

command from the previous post, the extra '*h*' option tells it to hide the header (You cant do 'SZ + 5 + 6'!) and the new `tr`

command translate or delete characters

(from the *manual pages*). So this strips out all new lines and puts a '+' after each number. The reason we need to `echo 0`

onto the end is because if we didn't we would end up with `1+2+3+`

. The `bc`

command is a *basic calculator* and will just add up whatever numbers it gets!

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So, `ps`

produces a column of numbers, `tr`

concatenates each newline-separated number with a '+' symbol. A zero is added to the end of the string and finally the entire string of numbers are parsed using the `bc`

command.

The result is a single number which represents the number of **kilobytes** currently in use by your applications.