What are the advanced uses of the free command in Linux?

In Linux systems, the free command is an important system tool used to monitor system memory usage. It provides basic usage to view information such as total memory, used amount, and available amount. In addition, there are some advanced uses, such as displaying detailed memory information, unit conversion, and real-time monitoring of memory.

Basic usage of free command:

The basic syntax of the free command is as follows:

free [选项]

The following are some commonly used options:

• -h: Display memory size in human-readable form.
• -b: Display memory size in bytes.
• -k: Display memory size in kilobytes.
• -m: Display memory size in megabytes.
• -g: Display memory size in gigabytes.

Sample code:

Let us use sample code to demonstrate the basic usage of the free command and check the system memory usage.

Use the free command to view memory information:

$ free

Output result analysis:

The output of the free command contains multiple lines of information, of which the "Mem" line and the "Swap" line are of interest. Sample output is as follows:

total used free shared buff/cache available
Mem: 2048572 1441912 160136 123404 445524 431120
Swap: 2097148 0 2097148

• The "total" column represents the total amount of memory.
• The "used" column represents the amount of memory used.
• The "free" column represents the amount of memory available.
• The "shared" column indicates the amount of memory that is shared.
• The "buff/cache" column indicates the amount of memory being cached.
• The "available" column represents the amount of memory available for the new process.

Advanced usage of free command:

In addition to basic usage, the free command also provides multiple advanced functions, let us learn about them one by one.

Show memory details:

$ free -l

This command will display more detailed memory information, including the address, size and type of the memory segment.

Display memory size using different units:

$ free -m

The above command will display the memory size in megabytes for easy reading.

Real-time monitoring of memory changes:

$ free -s 2

The above command will automatically refresh and display memory usage every 2 seconds.

Display total memory:

$ free -t

This command will display the memory total in the last line of the output result.

Only display memory or swap space information:

$ free -m -t

The above command will only display the sum of memory and swap space, without displaying other details.

in conclusion:

Through the free command, we can easily view and monitor the memory usage in the Linux system. Basic usage can help us understand basic information such as the total amount of memory, used amount, and available amount. The advanced usage provides more functions, such as displaying detailed memory information, unit conversion, real-time monitoring, etc., allowing us to better understand and manage system memory.

I hope this article can help readers master the basic and advanced usage of the free command, and can use it flexibly in daily Linux system management to better optimize and monitor the system's memory resources.

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