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选题[tech]: 20240109 Free Command Examples
sources/tech/20240109 Free Command Examples.md
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sources/tech/20240109 Free Command Examples.md
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[#]: subject: "Free Command Examples"
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[#]: via: "https://itsfoss.com/free-command/"
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[#]: author: "Sagar Sharma https://itsfoss.com/author/sagar/"
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[#]: collector: "lujun9972/lctt-scripts-1700446145"
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[#]: translator: " "
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[#]: reviewer: " "
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[#]: publisher: " "
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[#]: url: " "
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Free Command Examples
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======
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The free command is one of the easiest ways one can learn about their system memory (RAM) consumption and if you have swap enabled.
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But the question is: How can you use the free command? Well, it is pretty easy and does not require any complex steps.
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So in this tutorial, I will walk you through using the free command with examples along with exercise questions for you to practice.
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### How to use the free command in Linux
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To use free or any other command, it is a good idea to start with the command syntax, and I'll start with the same.
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Here's the syntax for the free command:
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```
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free [options]
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```
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You are given multiple options which are supposed to be used in the `[options]` field to change the default behavior of the free command.
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Now, allow me to share some commonly used options with the free command:
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Option | Description
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---|---
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`-h` | Print information in human-readable form by adjusting data units in KB, GB, etc.
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`-s ` | Update the free output after a given seconds of interval.
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`-t` | Shows the total amount of system and swap memory.
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`-g` | Display data in gigabytes.
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`-m` | Print information in megabytes.
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`-k` | Shows output in kilobytes.
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But what if you execute the free command without options? Here's what you can expect:
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![][1]
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Here,
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* `total`: it indicates the total amount of storage.
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* `used`: shows the utilized storage by your system.
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* `free`: the amount of free memory that is available for new processes.
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* `shared`: amount of memory used by tmpfs (temporary filesystem).
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* `buff/cache`: represents the sum of the memory used by buffers and cache.
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* `available`: it estimates how much memory is available to start a new application without swapping. It is a sum of the `free` memory and a part of the `buff/cache` which can be immediately used.
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So, if you want all kinds of information, just type in the command with no flags.
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Now, let's look at some examples of the free command.
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#### 1\. Display information in human-readable form
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By default, the free command will display the data in kibibytes which is not the most human-readable form you can have.
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That's where the `-h` options come into play which prints values in human-readable form such as in KB or GBs.
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```
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free -h
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```
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![][2]
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#### 2\. Show statistics continuously
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Once you execute the free command, it will only show you stats of the time when you executed the command. For example, if I executed the `free` command at `12:45` then, it will display the stats of that time only.
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So the question is: How you can achieve a similar behavior like [htop][3] which shows the live stats? Not exactly the same, but you can refresh the stats at specific time intervals using the `-s` flag as shown here:
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```
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free -s <seconds>
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```
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For example, if I want to refresh the free command every second, then I will use the following command:
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```
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free -s 1
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```
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**Suggested Read 📖**
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![][4]
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#### 3\. Define how many times to display the stats
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In a previous example, I explained how you can use the free command to show stats continuously, but you may not want it to refresh endlessly instead, a few times only.
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For that purpose, you can use the `-c` flag as shown here:
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```
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free -c <times_to_show_stats>
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```
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Let's say I want to see the stats 3 times, then I will be using the following:
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```
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free -c 3
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```
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![][5]
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By default, it will refresh the data every second but you can use the `-s` flag to specify the interval time:
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```
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free -c <times_to_show_stats> -s <seconds>
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```
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For example, here, if I would like to display stats 3 times with intervals of 2 seconds, then I will be using the following command:
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```
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free -c 3 -s 2
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```
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![][6]
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#### 4\. Specify the output datatype
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While for most users, using the `-h` flag to display data in human-readable form would get the job done, but what if you want to specify the data type by yourself?
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Well, you can specify the datatype using the following flags:
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Flag | Description
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`--kilo` | Display memory in kilobytes.
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`--mega` | Display memory in megabytes.
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`--giga` | Display memory in gigabytes.
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`--tera` | Display memory in terabytes.
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You can use the above flags in the following manner:
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```
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free --<kilo/mega/giga/tera>
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```
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For example, if I wish to display memory stats in megabytes, then, I will use the following:
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```
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free --mega
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```
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![][7]
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#### 5\. Get the sum of physical and swap memory
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By default, the free memory will show the row of physical and swap memory, but what if you want to get the sum of them?
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Well, you can use the `-t` flag:
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```
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free -t
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```
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### Exercise questions 👨💻
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Here are some questions that you can practice to get better at using the free command:
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* Print memory stats continuously for 3 times, with an interval of 3 seconds in between.
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* Get the sum of physical and swap memory but in human-readable form.
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* Redirect the output of the free command in the text file.
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* How to print only one column from the output of the free command? (Hint: use [awk command][9] and specify column number).
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If you have any doubts regarding the questions, you can reach out to us in our [community forum][10] or leave a comment here.
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### Wrapping Up
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Every single command comes in handy in one way or the other. The free command also has one such underrated use-case to get useful information.
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If you are just getting started with a Linux terminal, we made a series for users like you who are eager to learn but can't find a place to start:
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![][4]
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_💬 I hope you find this guide useful! Please let me know your thoughts on what should I cover next?_
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--------------------------------------------------------------------------------
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via: https://itsfoss.com/free-command/
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作者：[Sagar Sharma][a]
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选题：[lujun9972][b]
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译者：[译者ID](https://github.com/译者ID)
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校对：[校对者ID](https://github.com/校对者ID)
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本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
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[a]: https://itsfoss.com/author/sagar/
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[b]: https://github.com/lujun9972
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[1]: https://itsfoss.com/content/images/2024/01/Use-free-command-without-any-options.png
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[2]: https://itsfoss.com/content/images/2024/01/Get-human-readable-data-through-the-free-command-in-Linux.png
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[3]: https://itsfoss.com/use-htop/
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[4]: https://itsfoss.com/content/images/size/w256h256/2022/12/android-chrome-192x192.png
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[5]: https://itsfoss.com/content/images/2024/01/Specify-how-many-times-the-free-command-should-display-the-stats.gif
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[6]: https://itsfoss.com/content/images/2024/01/Specify-how-many-times-the-free-command-should-display-the-stats-with-custom-intevals.gif
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[7]: https://itsfoss.com/content/images/2024/01/Print-memory-statistics-in-megabytes-using-the-free-command-in-Linux.png
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[8]: https://itsfoss.com/content/images/2024/01/Get-the-sum-of-physical-and-swap-memory-using-the-free-command.png
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[9]: https://linuxhandbook.com/awk-command-tutorial/
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[10]: https://itsfoss.community/
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