The Random Access Memory (RAM) is a hardware device that allows an information to be stored and retrieved on a computer. RAM is usually associated with DRAM, which is a type of memory module.

Memory is one of the most important things to determine the performance of a server. It’s often important to check the RAM usage by using shell commands. ” free” command is a simple command to check the total used and available space of physical memory and swap memory with buffers.

Log in to the server as a root and use these commands to check the usage of RAM.


# free–  It is used to check the available space of swap memory and physical memory in KB.

# free-b – Displays the size of memory in bytes.

# free-k – Displays the size of memory in Kilobytes(Kb).

# free-m – Displays the size of memory in Megabytes(Mb).

# free-g – Displays the size of memory in Gigabytes(GB).

# free-t – Displays the list of the total line at the end.

# free-o – Displays “Buffer adjusted line” to disable the line use option

# free-s 5 – Uses the number to update at regular intervals. here 5 is used so that it can be updated for every 5 seconds.

# free-l – Displays detailed statistics about high and low memory size.

# free-V – Displays free command version information.

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