Merge pull request #30753 from lujun9972/add-MjAyNDAxMDkgRnJlZSBDb21tYW5kIEV4YW1wbGVzLm1kCg==

自动选题[tech]: 20240109 Free Command Examples
2024-12-23 21:20:42 +08:00 · 2024-01-10 15:15:37 +08:00 · 2024-01-10 15:15:37 +08:00 · 64c39ce9bf
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+[#]: subject: "Free Command Examples"
+[#]: via: "https://itsfoss.com/free-command/"
+[#]: author: "Sagar Sharma https://itsfoss.com/author/sagar/"
+[#]: collector: "lujun9972/lctt-scripts-1700446145"
+[#]: translator: " "
+[#]: reviewer: " "
+[#]: publisher: " "
+[#]: url: " "
+
+Free Command Examples
+======
+
+The free command is one of the easiest ways one can learn about their system memory (RAM) consumption and if you have swap enabled.
+
+But the question is: How can you use the free command? Well, it is pretty easy and does not require any complex steps.
+
+So in this tutorial, I will walk you through using the free command with examples along with exercise questions for you to practice.
+
+### How to use the free command in Linux
+
+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.
+
+Here's the syntax for the free command:
+
+```
+
+    free [options]
+
+```
+
+You are given multiple options which are supposed to be used in the `[options]` field to change the default behavior of the free command.
+
+Now, allow me to share some commonly used options with the free command:
+
+Option | Description
+---|---
+`-h` | Print information in human-readable form by adjusting data units in KB, GB, etc.
+`-s ` | Update the free output after a given seconds of interval.
+`-t` | Shows the total amount of system and swap memory.
+`-g` | Display data in gigabytes.
+`-m` | Print information in megabytes.
+`-k` | Shows output in kilobytes.
+
+But what if you execute the free command without options? Here's what you can expect:
+
+![][1]
+
+Here,
+
+  * `total`: it indicates the total amount of storage.
+  * `used`: shows the utilized storage by your system.
+  * `free`: the amount of free memory that is available for new processes.
+  * `shared`: amount of memory used by tmpfs (temporary filesystem).
+  * `buff/cache`: represents the sum of the memory used by buffers and cache.
+  * `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.
+
+
+
+So, if you want all kinds of information, just type in the command with no flags.
+
+Now, let's look at some examples of the free command.
+
+#### 1\. Display information in human-readable form
+
+By default, the free command will display the data in kibibytes which is not the most human-readable form you can have.
+
+That's where the `-h` options come into play which prints values in human-readable form such as in KB or GBs.
+
+```
+
+    free -h
+
+```
+
+![][2]
+
+#### 2\. Show statistics continuously
+
+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.
+
+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:
+
+```
+
+    free -s <seconds>
+
+```
+
+For example, if I want to refresh the free command every second, then I will use the following command:
+
+```
+
+    free -s 1
+
+```
+
+**Suggested Read 📖**
+
+![][4]
+
+#### 3\. Define how many times to display the stats
+
+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.
+
+For that purpose, you can use the `-c` flag as shown here:
+
+```
+
+    free -c <times_to_show_stats>
+
+```
+
+Let's say I want to see the stats 3 times, then I will be using the following:
+
+```
+
+    free -c 3
+
+```
+
+![][5]
+
+By default, it will refresh the data every second but you can use the `-s` flag to specify the interval time:
+
+```
+
+    free -c <times_to_show_stats> -s <seconds>
+
+```
+
+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:
+
+```
+
+    free -c 3 -s 2
+
+```
+
+![][6]
+
+#### 4\. Specify the output datatype
+
+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?
+
+Well, you can specify the datatype using the following flags:
+
+Flag | Description
+---|---
+`--kilo` | Display memory in kilobytes.
+`--mega` | Display memory in megabytes.
+`--giga` | Display memory in gigabytes.
+`--tera` | Display memory in terabytes.
+
+You can use the above flags in the following manner:
+
+```
+
+    free --<kilo/mega/giga/tera>
+
+```
+
+For example, if I wish to display memory stats in megabytes, then, I will use the following:
+
+```
+
+    free --mega
+
+```
+
+![][7]
+
+#### 5\. Get the sum of physical and swap memory
+
+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?
+
+Well, you can use the `-t` flag:
+
+```
+
+    free -t
+
+```
+
+![][8]
+
+### Exercise questions 👨‍💻
+
+Here are some questions that you can practice to get better at using the free command:
+
+  * Print memory stats continuously for 3 times, with an interval of 3 seconds in between.
+  * Get the sum of physical and swap memory but in human-readable form.
+  * Redirect the output of the free command in the text file.
+  * How to print only one column from the output of the free command? (Hint: use [awk command][9] and specify column number).
+
+
+
+If you have any doubts regarding the questions, you can reach out to us in our [community forum][10] or leave a comment here.
+
+### Wrapping Up
+
+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.
+
+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:
+
+![][4]
+
+_💬 I hope you find this guide useful! Please let me know your thoughts on what should I cover next?_
+
+--------------------------------------------------------------------------------
+
+via: https://itsfoss.com/free-command/
+
+作者：[Sagar Sharma][a]
+选题：[lujun9972][b]
+译者：[译者ID](https://github.com/译者ID)
+校对：[校对者ID](https://github.com/校对者ID)
+
+本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
+
+[a]: https://itsfoss.com/author/sagar/
+[b]: https://github.com/lujun9972
+[1]: https://itsfoss.com/content/images/2024/01/Use-free-command-without-any-options.png
+[2]: https://itsfoss.com/content/images/2024/01/Get-human-readable-data-through-the-free-command-in-Linux.png
+[3]: https://itsfoss.com/use-htop/
+[4]: https://itsfoss.com/content/images/size/w256h256/2022/12/android-chrome-192x192.png
+[5]: https://itsfoss.com/content/images/2024/01/Specify-how-many-times-the-free-command-should-display-the-stats.gif
+[6]: https://itsfoss.com/content/images/2024/01/Specify-how-many-times-the-free-command-should-display-the-stats-with-custom-intevals.gif
+[7]: https://itsfoss.com/content/images/2024/01/Print-memory-statistics-in-megabytes-using-the-free-command-in-Linux.png
+[8]: https://itsfoss.com/content/images/2024/01/Get-the-sum-of-physical-and-swap-memory-using-the-free-command.png
+[9]: https://linuxhandbook.com/awk-command-tutorial/
+[10]: https://itsfoss.community/