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Free unused memory currently unavailable

Terminal - Free unused memory currently unavailable
dd if=/dev/zero of=junk bs=1M count=1K
2009-11-01 23:45:51
User: guedesav
Functions: dd
-11
Free unused memory currently unavailable

This is an useful command for when your OS is reporting less free RAM than it actually has. In case terminated processes did not free their variables correctly, the previously allocated RAM might make a bit sluggis over time.

This command then creates a huge file made out of zeroes and then removes it, thus freeing the amount of memory occupied by the file in the RAM.

In this example, the sequence will free up to 1GB(1M * 1K) of unused RAM. This will not free memory which is genuinely being used by active processes.

Alternatives

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Terminal - Alternatives

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What others think

To free cached memory, you can also do:

sudo echo 3 > /proc/sys/vm/drop_caches

Then in order allow caching again

sudo echo 0 > /proc/sys/vm/drop_caches
Comment by alperyilmaz 260 weeks and 4 days ago

I am lost. Where in the command does it remove it??

Comment by DaveQB 260 weeks and 4 days ago

When it removes the file.

Comment by guedesav 260 weeks and 2 days ago

Your point of view

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