mirror of
https://github.com/LCTT/TranslateProject.git
synced 2024-12-26 21:30:55 +08:00
1ee2fc7cbe
renamed: 10 Useful Chaining Operators in Linux with Practical Examples.md -> 201401/10 Useful Chaining Operators in Linux with Practical Examples.md renamed: 10 basic examples of linux netstat command.md -> 201401/10 basic examples of linux netstat command.md renamed: 12 Advanced Commands For Linux Server Admins!.md -> 201401/12 Advanced Commands For Linux Server Admins!.md renamed: 14 New Linux Distros That Were Introduced In 2013.md -> 201401/14 New Linux Distros That Were Introduced In 2013.md renamed: 15 Basic MySQL Interview Questions for Database Administrators.md -> 201401/15 Basic MySQL Interview Questions for Database Administrators.md renamed: "2013\357\274\232The Golden Year for Linux \342\200\223 10 Biggest Linux Achievements.md" -> "201401/2013\357\274\232The Golden Year for Linux \342\200\223 10 Biggest Linux Achievements.md" renamed: 2014--The year of the Linux car.md -> 201401/2014--The year of the Linux car.md renamed: 5 Things To Love And Hate About Ubuntu 13.10.md -> 201401/5 Things To Love And Hate About Ubuntu 13.10.md renamed: 8 Interesting Linux Tips And Tricks!.md -> 201401/8 Interesting Linux Tips And Tricks!.md renamed: CentOS 6.5 desktop installation guide with screenshots.md -> 201401/CentOS 6.5 desktop installation guide with screenshots.md renamed: "Command Line Basics \342\200\223 watch.md" -> "201401/Command Line Basics \342\200\223 watch.md" renamed: Configure Your Browser To Use Tor On Ubuntu or Debian or Linux Mint.md -> 201401/Configure Your Browser To Use Tor On Ubuntu or Debian or Linux Mint.md renamed: Daily Ubuntu Tips - Mount Partitions In Ubuntu From Your Desktop GUI.md -> 201401/Daily Ubuntu Tips - Mount Partitions In Ubuntu From Your Desktop GUI.md renamed: "Daily Ubuntu Tips \342\200\223 Do Nothing When Laptop Lid Is Closed.md" -> "201401/Daily Ubuntu Tips \342\200\223 Do Nothing When Laptop Lid Is Closed.md" renamed: "Daily Ubuntu Tips \342\200\224 Install VMware Workstation In Ubuntu.md" -> "201401/Daily Ubuntu Tips \342\200\224 Install VMware Workstation In Ubuntu.md" renamed: "Daily Ubuntu Tips \342\200\224 Windows Disk Management Equivalent In Ubuntu.md" -> "201401/Daily Ubuntu Tips \342\200\224 Windows Disk Management Equivalent In Ubuntu.md" renamed: "Gnu--toward the post-scarcity world \342\200\223 the Free Software Column.md" -> "201401/Gnu--toward the post-scarcity world \342\200\223 the Free Software Column.md" renamed: How to Dual Boot Ubuntu and Windows Properly.md -> 201401/How to Dual Boot Ubuntu and Windows Properly.md renamed: "How to Install and Configure UFW \342\200\223 An Un-complicated FireWall in Debian or Ubuntu.md" -> "201401/How to Install and Configure UFW \342\200\223 An Un-complicated FireWall in Debian or Ubuntu.md" renamed: How to Upgrade to GNOME 3.10 in Ubuntu 13.10.md -> 201401/How to Upgrade to GNOME 3.10 in Ubuntu 13.10.md renamed: How to install and configure Nagios on Linux.md -> 201401/How to install and configure Nagios on Linux.md renamed: How to set password policy on Linux.md -> 201401/How to set password policy on Linux.md renamed: How to stitch photos together on Linux.md -> 201401/How to stitch photos together on Linux.md renamed: How to upgrade MySQL server on Debian or Ubuntu.md -> 201401/How to upgrade MySQL server on Debian or Ubuntu.md renamed: Juju ice-cream icon design.md -> 201401/Juju ice-cream icon design.md renamed: Linus Torvalds Releases Last Linux Kernel 3.13 RC for 2013.md -> 201401/Linus Torvalds Releases Last Linux Kernel 3.13 RC for 2013.md renamed: Linus Torvalds Says All Contributor License Agreements Are Broken.md -> 201401/Linus Torvalds Says All Contributor License Agreements Are Broken.md renamed: Linux free Command - Display Free and used Memory in the System.md -> 201401/Linux free Command - Display Free and used Memory in the System.md renamed: Linux id Command - Print user ID and group ID information.md -> 201401/Linux id Command - Print user ID and group ID information.md renamed: Linux is Everywhere. We show you exactly where.md -> 201401/Linux is Everywhere. We show you exactly where.md renamed: Linux lsusb Command to Print information about USB on System.md -> 201401/Linux lsusb Command to Print information about USB on System.md renamed: Linux vmstat Command - Tool to Report Virtual Memory Statistics.md -> 201401/Linux vmstat Command - Tool to Report Virtual Memory Statistics.md renamed: "Linux who command \342\200\223 Displays who is on the system.md" -> "201401/Linux who command \342\200\223 Displays who is on the system.md" renamed: "Move Dropbox\342\200\231s Folder To An External Drive In Ubuntu.md" -> "201401/Move Dropbox\342\200\231s Folder To An External Drive In Ubuntu.md" renamed: New Ubuntu 14.04 Icons Are Drop-Dead Gorgeous, Might Not Arrive in Desktop Version.md -> 201401/New Ubuntu 14.04 Icons Are Drop-Dead Gorgeous, Might Not Arrive in Desktop Version.md renamed: Our Top 10 Linux Applications of 2013.md -> 201401/Our Top 10 Linux Applications of 2013.md renamed: Setup your personal Cloud server in minutes using ownCloud On RHEL, CentOS, Scientific Linux 6.5.md -> 201401/Setup your personal Cloud server in minutes using ownCloud On RHEL, CentOS, Scientific Linux 6.5.md renamed: Software May Be Eating The World, But Open Source Software Is Eating Itself.md -> 201401/Software May Be Eating The World, But Open Source Software Is Eating Itself.md renamed: The Debian Administrator's Handbook updated for Debian 7 Wheezy published and freely available for download.md -> 201401/The Debian Administrator's Handbook updated for Debian 7 Wheezy published and freely available for download.md renamed: The Fedora Project Will No Longer Name Its Linux Distributions.md -> 201401/The Fedora Project Will No Longer Name Its Linux Distributions.md renamed: The Genius Of Linux Is Community, Not Technology.md -> 201401/The Genius Of Linux Is Community, Not Technology.md renamed: Top 10 Linux Distros For Hackers!.md -> 201401/Top 10 Linux Distros For Hackers!.md renamed: Tunnel SSH Connections Over SSL Using 'Stunnel' On Debian 7 Ubuntu 13.10.md -> 201401/Tunnel SSH Connections Over SSL Using 'Stunnel' On Debian 7 Ubuntu 13.10.md renamed: Ubuntu Stores Your Wi-Fi Passwords By Default!.md -> 201401/Ubuntu Stores Your Wi-Fi Passwords By Default!.md renamed: Ubuntu Will Reach True Convergence Before Microsoft, Says Shuttleworth.md -> 201401/Ubuntu Will Reach True Convergence Before Microsoft, Says Shuttleworth.md renamed: Understanding Linux cd Command with Examples.md -> 201401/Understanding Linux cd Command with Examples.md renamed: look--Linux Command To Verify Spellings And Display Lines Beginning With A String.md -> 201401/look--Linux Command To Verify Spellings And Display Lines Beginning With A String.md
101 lines
4.9 KiB
Markdown
101 lines
4.9 KiB
Markdown
Linux free 命令 - 显示系统中空闲和已使用的内存
|
||
================================================================================
|
||
系统管理员必须维护他们服务器的健康运行。其中一个重要的部分就是内存。当服务器内存使用率过高时，它会降低服务器的性能。Linux有一个称为 **free** 的工具，来监控内存使用率。
|
||
|
||
### free 命令是什么 ###
|
||
|
||
**free** 命令是一个显示系统中空闲和已用内存大小的工具。free 命令的输出和 top 命令相似。大多数Linux发行版已经含有 free 命令。
|
||
|
||
### 如何运行 free ###
|
||
|
||
想要运行，只需在控制台输入**free** 即可。不带选项运行会显示一个以KB为单位的默认输出。
|
||
|
||
$ free
|
||
|
||
|
||
|
||
从上面的截图我们看到：
|
||
|
||
#### 内存 (以KB计) ####
|
||
|
||
- Total（全部） : 1026740
|
||
- Used（已用） : 843396
|
||
- Free（可用） : 183344
|
||
- Shared（共享） : 0
|
||
- Buffers（块设备缓存区） : 52704
|
||
- Cached（文件缓存） : 376384
|
||
|
||
译注：关于Buffers和Cached的区别，来自 http://www.taobaotesting.com/blogs/qa?bid=2265 的一段解释如下：
|
||
|
||
> buffers是指用来给块设备做的缓冲大小，他只记录文件系统的metadata以及 tracking in-flight pages.
|
||
|
||
> cached是用来给文件做缓冲。
|
||
|
||
> 那就是说：buffers是用来存储，目录里面有什么内容，权限等等。而cached直接用来记忆我们打开的文件
|
||
|
||
#### Swap (以KB计) ####
|
||
|
||
- Total（全部） : 1045500
|
||
- Used（已用） : 3376
|
||
- Free（可用） : 1042124
|
||
|
||
当你看见 buffer/cache 的空闲空间低或者 swap 的空闲空间低，说明内存需要升级了。这意味这内存利用率很高。请注意 **shared（共享）内存列应该被忽略** ，因为它已经被废弃了。
|
||
|
||
### 以其它单元显示内存信息 ###
|
||
|
||
如我们先前提到的，默认 free 会以 KB 为单位显示信息。free 同样提供给我们 **b (B), -k (KB), -m (MB), -g (GB) and –tera (TB)**这些单位。要显示我们想要的单位，只要选择一个并在 free 后面跟上。下面一个是以 MB 为单位的输出样例。
|
||
|
||
$ free -m
|
||
|
||
|
||
|
||
这个技巧同样适用于**-b, -k, -g** 以及 **–tera** 选项。
|
||
|
||
### 以适于人类可读方式显示内存信息 ###
|
||
|
||
free 同样提供了**-h**选项，这意味着适于人类可读(译注:系统上可能并不存在-h选项，已被-m取代)。那么这与其它的选项有什么不同呢，如**-m**(MB)选项？ 可见的最大不同是**-h**选项会在数字后面加上适于人类可读的单位。让我们看一个例子。
|
||
|
||
$ free -h
|
||
|
||
|
||
|
||
如我们一起看到的，在1,0数字后这里是**G(GB)**字母。当数字并没有达到GB时，free足够聪明来知道并在每个数字后面跟上合适的单位。后面的**M** - 数字929告诉我们它有929MB(译注: 原文为929 number tell us its 969 Megabytes，这里应该为输入错误)。
|
||
|
||
### 间隔显示 free ###
|
||
|
||
作为一个状态检查工具，最好的统计内存利用率的方法是使用延迟间隔。这么做的话，我们可以使用**-s**选项后面跟上我们想要间隔的N秒数。我们可以在后面合并几个选项来使输出满足我们的需求。假如我们想要每3秒统计一次内存利用率并且适于人类可读，那么就像这样做:
|
||
|
||
$ free -hs 3
|
||
|
||
|
||
|
||
### 显示高低内存利用率 ###
|
||
|
||
如果我们想要知道高低内存统计，我们可以使用-l选项。下面是一个例子。
|
||
|
||
$ free -l
|
||
|
||
|
||
|
||
### 显示 Linux 全部内存 ###
|
||
|
||
如果我们需要每列的总计信息，我们可以在 free 命令后面跟上 **-t** 选项。这会在字底部额外加入一行显示。
|
||
|
||
$ free -t
|
||
|
||
|
||
|
||
### 总结 ###
|
||
|
||
除了[vmstat][1]以外，free 命令也是一个用于统计内存利用率的简单统计工具。用这个你可以快速查看你的 Linux 内存信息。free 命令使用 **/proc/meminfo** 作为基准来显示内存利用率信息。如往常一样，你可以在控制台下输入 **man free** 来获取更多关于 free 的信息。
|
||
|
||
--------------------------------------------------------------------------------
|
||
|
||
via: http://linoxide.com/linux-command/linux-free-command/
|
||
|
||
译者：[geekpi](https://github.com/geekpi) 校对：[Caroline](https://github.com/carolinewuyan)
|
||
|
||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创翻译，[Linux中国](http://linux.cn/) 荣誉推出
|
||
|
||
[1]:http://linoxide.com/linux-command/linux-vmstat-command-tool-report-virtual-memory-statistics/
|