Syntax highlighting of Drop_Caches

Kernels 2.6.16 and newer provide a mechanism to have the kernel drop the page cache and/or inode and dentry caches on command, which can help free up a lot of memory.  Now you can throw away that script that allocated a ton of memory just to get rid of the cache...

To use `/proc/sys/vm/drop_caches`, just echo echo a number to it.

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
}}}