How to clear cached memory in Debian?

Question

If I run a free -m, I get this output:

Free -m output

Is there a command that I could use to clear the used memory? I have tried this:

echo 1 > /proc/sys/vm/drop_caches

It will ask for sudo. But even after sudo, it gives bad command error.

Here is the link where I got to know about drop_caches.

I am just looking for a way on how to clear the cache.

I want to test the performance of an application , which initiates several processes , and generate some statistics , If i run the same application for two times the statistics will not be accurate , and also clear understanding of how the application behaves in each of scenarios , will remain as a mystery . If cache is the matter for its performance , I definitely need to know if there is any way there to clear the cache so that I can take care of it . I am really sorry , If this stack overflow is not a platform to ask such system level questions .

TOC · Accepted Answer · 2012-09-02 03:44:36Z

up vote 4 down vote accepted

Try this as root (not sudo):

#sync && echo 3 > /proc/sys/vm/drop_caches

answered Sep 2 '12 at 3:44

TOC
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migrated from stackoverflow.com Sep 5 '12 at 3:30