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Does not output the word "shared" so you can easily store this number in a variable.
run sync first to flush useful things out to disk!!!
To free pagecache:
echo 1 > /proc/sys/vm/drop_caches
To free dentries and inodes:
echo 2 > /proc/sys/vm/drop_caches
To free pagecache, dentries and inodes:
echo 3 > /proc/sys/vm/drop_caches
This will show the amount of physical RAM that is left unused by the system.
Here we instead show a more real figure for how much free RAM you have when taking into consideration buffers that can be freed if needed.
Unix machines leave data in memory but marked it free to overwrite, so using the first line from the "free" command will mostly give you back a reading showing you are almost out of memory, but in fact you are not, as the system can free up memory as soon as it is needed.
I just noticed the free command is not on my OpenBSD box.