## github多账号如何切换？

git多账号切换其实是有https的解决方案的，可以省去ssh配置公钥相关的麻烦，不过安全性会降低，后面会提到。

https开头的就是用的https了，git@ 开头的就是用的ssh了，一般用浏览器打开github仓库页面之后在页面里copy的都是https。一般是长这个样子：

github.com/UserA/repoA.

1. 清空global和system的credential.helper
2. 对每一个本地仓库，设置一下url和local的credential.helper

## The TeX family tree: LaTeX, pdfTeX, XeTeX, LuaTeX and ConTeXt

The LaTeX story goes back all the way to 1977 when Donald Knuth first understood the need for a high quality typesetting program. It’s a remarkable testament to the quality of LaTeX that the system he conceived back then is still the best tool for the job today, although many useful additions have been made in the decades since. In fact, LaTeX is one of these additions to the original system that Donald Knuth developed, which was called TeX.

To keep your street-cred in the LaTeX-world you’ve got write it with a capital T and X, and pronounce it like Lay-Tech. This is because the X in TeX is actually a capital Chi (χ) from Greek. Latex with a normal capitalisation and pronunciation is a type of rubber!

## The original TeX

There are a large family of tools which are now derived from TeX, and it can look like a list of nonsense words on first sight: LaTeX, pdfTeX, XeLaTeX, LuaTeX, ConTeXt, and so on. The ancestor of all of these is of course the original TeX program by Knuth. This takes a document in plain text and transforms it into a beautifully typeset document. Knuth was quite particular about typesetting and the attention to detail in TeX is clear. An example TeX document might look something like this:

The output of this after running it through the TeX program is:

Notice how the combinations of letters ‘fi’, ‘fj’, and ‘ff’ in the example words run together in a pleasant way, and how the mathematics symbols are well spaced. On a larger scale, TeX does a very good job of breaking lines in the appropriate places to created well justified text, with hyphenations where appropriate.

Not only does it typeset text nicely, it also has a selection of commands, like \bye and \TeX in the example above. These can do simple things like change the font size, or change the way text is laid out, as well as much more powerful things like keeping a section count to cross reference your pages, or automatically building up a table of contents. The TeX program has about 300 commands built in, but other commands can be defined within it. Donald Knuth wrote another 600 or so useful commands from within TeX, in a package called Plain TeX which makes some common typesetting tasks easier.

## LaTeX

The commands in TeX and Plain TeX are still quite basic and it isn’t easy to do complicated things with them. To help with this, Leslie Lamport created LaTeX in the early 1980s to provide a higher level language to work in than TeX. LaTeX is a set of commands defined in terms of the underlying TeX commands, often at many many layers of abstraction. All of the commands you use in a LaTeX document are actually just complicated sets of TeX commands underneath, unless of course you use a TeX command directly! Concepts like packages (\usepackage{...}), environments (\begin{environment} ... \end{environment}), and document classes (\documentclass{...}) were all introduced by Leslie Lamport in LaTeX.

By creating a standardised package system for LaTeX, Leslie Lamport allowed the community to grow huge. There are now thousands upon thousands of LaTeX packages available to let you typeset anything from subfigures to knitting patterns. There are also many document classes available for different types of document, whether your are writing a book, a lab report or a CV. Many publishers and journals have their own custom document classes that style their documents how they want.

## pdfTeX

The TeX program is remarkably stable for a piece of software over 20 years old; Knuth declared that it was feature complete in 1989, and only bug fixes have been made since. Of course, this has not stopped the significant and ongoing development of LaTeX, because that is written in TeX itself. In fact, the stability of TeX has allowed packages like LaTeX which have been built on top of it to thrive.

This isn’t to say the underlying TeX program hasn’t seen any advances in the last 20 years. Far from it in fact, it’s just that improvements have been made alongside TeX, with the original TeX left stable. The most important improvement of the 1990s was the creation of pdfTeX by Hàn Thế Thành for his PhD thesis. The original TeX program outputs the typeset document into a custom format called DVI (DeVice Independent format), that can later be turned into a PostScript file for printing. However, the PDF format came along in 1993 and we can see today that it clearly won as the better format over PostScript. There are lots of features which make PDF better, such as hyperlinks between sections, a section of metadata that lets you see a table of contents in left hand side of your PDF viewer, and support for a wider and more modern range of image formats. pdfTeX is a modification of TeX which allows it to output to PDF directly and so take advantage of these extra features.

When you install a LaTeX distribution on your system today, it actually comes with two different programs: tex, and pdftex. It also comes with another two programs on top of these: latex and pdflatex, but these are actually just wrappers around tex and pdftex respectively. These first load the LaTeX packages before processing your document but are still TeX underneath. If you run latex or tex then you will get a DVI file which you can turn into a postscript file or a PDF, but if you run pdflatex you will get a PDF directly.

Mostly, pdftex and pdflatex are improvements over tex and latex, but there is one downside. The original TeX and DVI format have support for Encapsulated PostScript files (.eps) because these can easily be included in PostScript files (produced by converting .dvi files to Postscript via Dvips). However, pdftex cannot include EPS files, and you should instead use PDFs (which can be produced from EPS files with the command epstopdf which generally comes with LaTeX distributions). In exchange for this downside though, pdfTeX adds support for .png.jpg and .pdf images, whereas the original TeX only supports .eps (via Dvips).

## XeLaTeX and LuaTeX

So far we have seen that TeX has evolved in two different ways since its beginning: With the addition of easier to use commands on top of the original system (LaTeX), and with updates to the underlying program to support PDF output (pdfTeX). The story does not stop there however and there have been continuing efforts to modernize TeX. In 2004 Jonathon Kew created XeTeX, which is another modification of the underlying TeX engine, this time to support a wider range of characters beyond just plain English numbers and letters, and to include support for modern font formats. This makes writing in foreign languages much easier, and also lets you use fonts within LaTeX which were traditionally only available to your word processor.

LuaTeX is an attempt to extend the original TeX program with a more sensible programming language. While in principle you can do absolutely anything from within TeX, in practice it’s a very clumsy programming language to work with, if it can even be called a programming language at all. Much of the internals of LaTeX is complicated and hard for outsiders to understand due to having to work only in TeX. LuaTeX is extended with the eponymous scripting language, Lua, which is a simple and stable language, ideal for writing complicated macros. As of 2012, it’s still in active development and is its API is liable to change, but it still very usable.

## ConTeXt

We’ve mentioned LaTeX as an extension to the commands available in TeX, but it’s not the only package that has extended TeX in a significant way. ConTeXt is another system which was created in 1990 by Hans Hagen. LaTeX aims to separate the user from having to make decisions about typography and layout (you type \section and \emph but you don’t worry about what these do – that’s left to the document class or layout). On the other hand, ConTeXt aims to provide an easy interface to advanced typography features. Sadly I don’t know as much about ConTeXt as I would like, so I can’t elaborate much further, but if I ever get round to experimenting with it more I’ll be sure to write up my findings.

As a final historical note, I should mention AMSTeX which was an extension to the Plain TeX macros and was used by the American Mathematical Society (AMS) from 1982 to 1985. Its legacy survives in AMS-LaTeX packages which are a staple of many LaTeX documents: \usepackage{amsmath}.

## The Future

What will the future hold for TeX and LaTeX? I don’t know yet, but as Alan Kay once said:

The best way to predict the future is to invent it.

With ShareLaTeX we hope to improve TeX and LaTeX in a third direction, by bringing significant improvements to the LaTeX workflow. Despite being over 20 years old, LaTeX is still largely a command line program that must be used in an awkward cycle of writing, compiling and checking the output. Methods of collaboration tend to involve clunky email messages rather than the streamlined processes available for word processing like Google Documents.

In 2 or 3 years time I hope that people will reflect back on online services like ShareLaTeX and be able to say that they have improved the way we work with LaTeX.

SOURCE: https://fr.overleaf.com/learn/latex/Articles/The_TeX_family_tree:_LaTeX,_pdfTeX,_XeTeX,_LuaTeX_and_ConTeXt

## Jaques Lacan

Entre l’homme et l’amour, il y a la femme.

Entre l’homme et la femme, il y a un monde.

Entre l’homme et le monde, il y a un mur.

Jacques Lacan ; cite les vers d’Antoine Tudal  (Paris en l’an 2000)

## What’s the difference between a “disc” and a “disk?”

They’re pronounced the same, but, technically speaking, there is a distinct difference between a disc and a disk.

## Discs

A disc refers to optical media, such as an audio CD, CD-ROM, DVD-ROM, DVD-RAM, or DVD-Video disc. Some discs are read-only (ROM), others allow you to burn content (write files) to the disc once (such as a CD-R or DVD-R, unless you do a multisession burn), and some can be erased and rewritten over many times (such as CD-RW, DVD-RW, and DVD-RAM discs).

All discs are removable, meaning when you unmount or eject the disc from your desktop or Finder, it physically comes out of your computer.

## Disks

A disk refers to magnetic media, such as a floppy disk, the disk in your computer’s hard drive, an external hard drive. Disks are always rewritable unless intentionally locked or write-protected. You can easily partition a disk into several smaller volumes, too.

Disks are usually sealed inside a metal or plastic casing (often, a disk and its enclosing mechanism are collectively known as a “hard drive”).

Published Date:

## 法国谚语

J’y suis,j’y reste.

C’est en forgeant qu’on devient forgeron.

Il n’y a pas de fumee sans feu.

être joli,e comme un coeur

être fort,e comme un Turc

être rouge comme un coq

connaître … comme sa poche

manger sur le pouce

Vouloir,c’est pouvoir.

Il n’y a que le premier pas qui coute

Rire bien qui rire le dernier!

Je pense donc je suis!

quand on parle du loup,on en voit la queue.

ouvvrez la porte et voyez la montagne.

comme ci,comme ca.

etre beau comme un dieu.

Je parle francais comme une vache espagnole.

filer a l’anglaise

petit a petit, l’oiseau fait son nis.

## 摧毁一个中年人有多容易

01  摧毁一个中年人，一双鞋就够了

02  不要命，也得要那一车货

03  他突然举手，做了个投降姿势

2017年岁末，中兴一名程序员跳楼。他被告知将裁员，股权也会被低价回收。当天监控显示，大约10点10分，该员工到达中兴通讯大楼。在一楼刷卡之后，他并没乘坐直梯，而是绕路，搭了扶手电梯，慢慢上2楼。或许那一刻，他还没下定决心。“上了扶梯不久，他突然举起双手，做了个投降姿势。那时他的脸色就非常难看了。”

04  只因一张罚单，她同丈夫饮了农药

05  女儿死死拉着他，跪了下来

13岁的黄傲雪今天很开心，她要去县城，给父亲送冬衣了。父亲说，他在县城做木工。家离县城只有20公里，但为了省车费，他已几个月没回家。“这次偷偷去找爸爸，爸爸看到我，一定会很惊喜吧！”

06  30多岁的大男人，忽然蹲在街边大哭起来

“我赔给你的，是儿子的救命钱。”

07  中年人有多疲惫，只有他们自己懂

“以前我们是梦想家，现在梦想没了，只剩家了。”

——寒风中的身影

《经济学人》杂志，把亚洲中年人称为“三明治一代”。

“一天忙活完，最舒服的事儿，就是到家停好车，赖在里面。不慌不忙放个曲儿，慢条斯理点根烟，最后正式开始发呆。”

“车的两头，一头是功名利禄，一头是柴米油盐。偶尔在中间躲躲，也挺好。”

-End-

(作者：竺可桢)

## 不要抛弃学问

（胡适 中国公学十八年级毕业赠言 1929年）

Dear Students of the Graduating Class,
As you are leaving your alma mater, I have nothing to offer you as a gift except a word of advice.
My advice is, “Never give up the pursuit of learning.” You have perhaps finished your college courses mostly for obtaining the diploma, or, in other words, out of sheer necessity. However, from now on you are free to follow your own bent in the choice of studies. While you are in the prime of life, why not devote yourselves to a special field of study? Youth will soon be gone never to return. And it will be too late for you to go into scholarship when in your declining years. Knowledge will do you a good return even as a means of subsistence. If you give up studies while holding a job, you will in a couple of years have had yourselves replaces by younger people. It will then be too late to remedy the situation by picking up studies again.
Some people say, “Once you have a job, you’ll come up against the urgent problem of making a living. How can you manage to find time to study? Even if you want to, will it be possible with no library or laboratory available?”
Now let me tell you this. Those who refuse to study for lack of a library will most probably continue to do so even though there is a library. And those who refuse to do research for lack of a laboratory will most probably continue to do so even though a laboratory is available. As long as you set your mind on studies, you will naturally cut down on food and clothing to buy books or do everything possible to acquire necessary instruments.
Time is no object. Charles Darwin could only work one hour a day due to ill health. Yet what a remarkable man he was! If you spend one hour a day reading 10 pages of a book, you can finish more than 3,600 pages a year, and 110,000 pages in 30 years.
Dear students, 110,000 pages will be quite enough to make a learned man of you. It will take you one hour to read three tabloids a day, and one and half hours to finish four rounds of mah-jong a day. Reading tabloids, playing mah-jong or striving to be a learned man, the choice lies with you.
”Henrik Ibsen says, “It is your supreme duty to cast yourself into a useful implement.”
Learning is the casting mould. Forsake learning, and you will ruin yourself.
Farewell! Your alma-mater is watching eagerly to see what will become of you ten years from now.