diff --git a/sources/tech/20240109 Free Command Examples.md b/sources/tech/20240109 Free Command Examples.md new file mode 100644 index 0000000000..df77781cbd --- /dev/null +++ b/sources/tech/20240109 Free Command Examples.md @@ -0,0 +1,231 @@ +[#]: 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 + +``` + +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 + +``` + +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 -s + +``` + +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 -- + +``` + +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/