Know your free and used memory in linux

To know your free and used memory in linus, just type in terminal

$ free 

The output will like : 

             total       used       free     shared    buffers     cached
Mem:       1024548     781992     242556          0      43240     407944
-/+ buffers/cache:     330808     693740
Swap:       975868          0     975868  

If you want more specific information then choose from command option :

-b, --bytes

Display output in bytes.

-k, --kb

Display output in kilobytes (KB). This is the default.

-m, --mb

Display output in megabytes (MB).

-g, --gb

Display output in gigabytes (GB).

-l, --lowhigh

Display detailed information about low vs. high memory usage.

-o, --old

Use old format. Specifically, do not display -/+ buffers/cache.

-t, --total

Display total summary for physical memory + swap space.

-c n, --count=n

Display statistics n times, then exit. Used in conjunction with the -s flag. Default is to display only once, unless -s was specified, in which case default is to repeat until interrupted.

-s n, --repeat=n

Repeat, pausing every n seconds in-between.

-V, --version

Display version information and exit.

--help

Display usage information and exit