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How were the weightings in the linux load computation chosen?

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问题 In Linux, the load average is said to be on 1min/5min/15min. The formula used by the kernel is actually an Exponential moving average. If we define cpuload(1) as the first computation of the cpu load 1min, and active() as the function returning the number of process in state "running" or "runnable" on the system, then the formula used by the kernel to compute the nth cpu load 1min is: cpuload(0) is 0; it is the value stored in memory before the first execution of cpuload() . My question is,

What is the format of shell history files

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问题 My ~/.zsh_history shows: : 1449561637:0;echo "foobar" I'm guessing it goes unix timestamp : exit code ; command but what about the space before the timestamp and first colon? Is there an official spec? 回答1: As already noted in the comments, the format of the history file depends on the shell and sometimes even on specific settings of the shell. In your case you are using zsh with the EXTENDED_HISTORY option enabled (either by explicitly setting it or by using csh -emulation). According to the

How can i get email history from iphone device..?

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问题 friends I want to access email history from my iphone & also want notification when new mail receive. Provide me source code snippet if possible. Thanks, 回答1: In short: It is not possible with any of the documented APIs 来源： https://stackoverflow.com/questions/7039370/how-can-i-get-email-history-from-iphone-device

五周第三次课（4月20日） 8.1 shell介绍 8.2 命令历史 8.3 命令补全和别名 8.4 通配符 8.5 输入输出重定向

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【推荐】2019 Java 开发者跳槽指南.pdf(吐血整理) >>> 第八章 shell基础 8.1 shell介绍 Shell是一个命令解释器，提供用户和机器之间的交互，支持特定的语法，比如逻辑判断、循环。每个用户都可以有自己特定的shell，CentOS7的默认shell为bash（Bourne Agin Shell），常见的还有zsh（power-shell）、ksh（Korn shell）。 8.2 命令历史（history） history命令语法： history [-c] -c：=clear 清除内存中的命令，不能删除配置文件中的历史命令 [root@adai003 ~]# history 1 ls 2 ls /tmp/ 3 ls /boot/ 4 ls / 5 dhclient …… [root@adai003 ~]# ls /root/.bash_history /root/.bash_history history的家目录显示使用过的命令历史，默认保存1000条使用过的命令（注：此令需要是在正常关机操作情况下的处1000条命）！ history环境变量变量HISTSIZE [root@cham2 ~]# echo $HISTSIZE 1000 该变量决定命令历史保存的命令的数目。定义变量HISTSIZE [root@cham2 ~]# [[root

Why is it thought of 'T name' to be the C way and 'T name' to be the C++ way?

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问题 Note: This question is about the position of the asterisk ( * ). In most C code I see (e.g., in Beej's guide to network programming), all variable declarations / definitions use the T *name format, i.e., bind the * to the variable name. The pointer is thought of belonging to the variable, not the type. In most C++ code I see, the format is T* name , i.e., it binds the * to the type of the variable . The pointer is thought of belonging to the type, not the variable. I myself, as a pure C++

CSS/JavaScript/hacking: Detect :visited styling on a link without checking it directly OR do it faster than me

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问题 This is for research purposes on http://cssfingerprint.com Consider the following code: <style> div.csshistory a { display: none; color: #00ff00;} div.csshistory a:visited { display: inline; color: #ff0000;} </style> <div id="batch" class="csshistory"> <a id="1" href="http://foo.com">anything you want here</a> <a id="2" href="http://bar.com">anything you want here</a> [etc * ~2000] </div> My goal is to detect whether foo has been rendered using the :visited styling. I want to detect whether

CSS/JavaScript/hacking: Detect :visited styling on a link without checking it directly OR do it faster than me

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How to find date wise history of commands being fired [duplicate]

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问题 This question already has answers here : Linux Command History with date and time (4 answers) Closed last year . How can I make the history command display the date and time information in addition to the command line? 回答1: The history of executed commands is stored by your shell. Try adding something like this to you ~/.bashrc export HISTTIMEFORMAT="%m/%d - %H:%M:%S: " It will change the HISTTIMEFORMAT variable and bash will store a timestamp in its history accordingly. Then your history

window bind POPSTATE

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问题 Given the following: $(window).bind("popstate", function() { alert('popstate'); }); On first load, the alert fires with FireFox and Chrome but not Safari. Why is that? Anyone else seen this and know how to best solve for this? 回答1: The situation is now reversed. Chrome has fixed the bug and now fires popstate on page load but Firefox 4 (since RC) has departed from the spec and now does not fire popstate! UPDATE : The HTML5 spec was changed in 2011 to state popstate should not fired on page

What does exclamation point stand for in HTML in constructs like DOCTYPE and comments?

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问题 I am curious about the syntax of the doctype and comment tags... Why the exclamation point? What is it called, what does it mean/do? I have read through the HTML syntax spec and found no real explanation other than Any case-insensitive match for the string <!DOCTYPE . Cite: http://www.w3.org/TR/html-markup/syntax.html#doctype-syntax 回答1: In SGML, which is what HTML was nominally based on, up to and including HTML 4.01, the exclamation mark is part of the construct <! , which is the reference