Ubuntu - Swap - Clear swap

free -m
 
                    total       used       free     shared    buffers     cached
 
Mem:          1024        157        866          0         11         48
 
-/+ buffers/cache:         97        926
 
Swap:          127         95         32

where

• -m is for the value to be listed in megabytes.

sync && /sbin/sysctl vm.drop_caches=3 && swapoff -a && swapon -a 

where

• sync is to force changed blocks to disk and update the super block;
• sysctl vm.drop_caches=3 is to free pagecache, dentries and inodes;
• swapoff is to turn off swap;
• swapon is to turn swap back on.

free -m
 
                    total       used       free     shared    buffers     cached
 
Mem:          1024        157        866          0         11         48
 
-/+ buffers/cache:         97        926
 
Swap:          127         0         127