access github through proxy

In China mainland, you never know for what reason a website gets blocked by the fucking GFW. Even if the site has nothing to do with politics. github is a example, many developers in China are victims. This post is about how to access github via a proxy, such as goagent.
The git pull/push command can be instructed to access remote server via proxy by setting https_proxy environment variable. So, we can run commands below use proxy.

https_proxy=http://127.0.0.1:8087 git pull

or

export https_proxy=http://127.0.0.1:8087
git push

But we may get below error because the goagent ssl certificate can't be verified.

error: SSL certificate problem: unable to get local issuer certificate while accessing https://github.com/xxxxxxxxxxx
fatal: HTTP request failed

To resolve this problem, we can force git not to verify ssl ceritificate by setting GIT_SSL_NO_VERIFY environment variable.

export GIT_SSL_NO_VERIFY=true
git pull

To make these settings perminately for a git project or globally. We can write them to git config file.

git config http.proxy http://127.0.0.1:8087
git config http.sslVerify false

The resulting .git/config file is like this:

[core]
    repositoryformatversion = 0
    filemode = true
    bare = false
    logallrefupdates = true
    ignorecase = true
[remote "origin"]
    url = https://github.com/rxwen/my_posts.git
    fetch = +refs/heads/*:refs/remotes/origin/*
[branch "master"]
    remote = origin
    merge = refs/heads/master
[http]
    proxy = http://127.0.0.1:8087
    sslVerify = false

BTW, there is a rumour that Fang BingXing gets ill badly recently. Wish Death can conquer him as soon as possible, amen.

avoid designing by coding

I found a obvious, stupid mistake in my c++ code. The mistake itself is trivial and doesn't worth mentioning. What I'm interested in is what lead me to making such a mistake that a very fresh c++ learner can easily recognize.
The main reason is I was designing by coding (implementing). Designing and coding are very separate tasks in a programming project. The goal of designing is to find out an effective way of organizing our code (classes, modules, layers, etc.) so that the code is easy to understand, maintain and to be changed. The goal of coding is implementing required features based on design. Because designing and coding have different goals, there are different ways to do them. But I chose to do them simultaneously, that is, thought about the design and wrote code immediately, even before I had a clear idea of the whole design. In this way, I always didn't have a sole goal in mind, but had to think about multiple things. It's not natural for human brain to work this way. Especially considering the complexity of c++ language, if we can't fully focus on the implementation details, we are very likely to be bitten by it. The case might be less painful if we work with other languages like c#, python, which have much less details to concern. But it's generally wise to choose a more suitable tool to do the design other than coding, for example UML, or other diagrams. And code review is a good way to get rid of such mistakes.

paste in vim command line

To be able to paste something to vim's command line is a feature makes our life a lot easier. For instance, say we want to change a frequently used variable name in c source file from a_super_long_inproper_variable_for_caching_bank_account_balance to balance. To replace all of the variable's occurrence, we plan to use following replace command:

:%s/a_super_long_inproper_variable_for_caching_bank_account_balance/balance/g

Without paste capability, we have to type the variable name ourself, maybe several times because we doom to type the name wrong.
Luckily, vim has at least two ways to rescue us from having to type the name.
1. command-line window
command-line window is a separate window that enables us editing command just like working in a normal window. Plus, it lists command history. So, we can easily copy the variable name via yank command and paste it to command-line window. To open the command-line window, we can type q: while in normal mode. For more information about command-line window, see help q: in vim.
2. paste with Ctrl+R shortcut key combination
Instead of opening a separate command-line window, we can also paste directly in vim command line. While editing within command line, we can use Ctrl+R, Ctrl+W key combination to paste the word currently under cursor in last window to command line. Beside the forgoing shortcut key, vim features a lot of key combination that let us paste from different sources, like registers, file name, etc. Run :help c_CTRL-R to find more out its real power.

Reference:
Vim documentation: cmdline

Total Commander, what a weapon!

I've used freecommander for years. It greatly improves my efficiency. Unfortunately, for some unkonwn reasons, my freecommander configuration file get corrupted after my machine power down unexpectedly several days before. Rather than making these configurations from scrarch again, I decided to give Total Commander a shot.

After I tried TC, I found it's far more powerful. TC is fully customizable, I can define any shortcut key combinations for TC internal commands or external commands defined by me. In FC, only Ctrl+[Number] is allowed to be set as shortcut key for external commands.

The most promising feature for TC is its plugin system. There are so many wonderful plugins that make TC so powerful. With packer plugin, I don't need a stand alone zip/tar/bzip2 applicaitons. With some creative filesystem plugins, task manager, regedit, dependency walker are not necessary any more. By using plugins, I can perform a lot of totally different tasks in a consistent manner, just manipulate some (fake) files in TC. This is very similar to abstraction in linux, where everything can be examined and manipulated like normal files. Abstract thinking should always be a popular idea among programmers, so I'm totally fascinated by TC.

Suggestions for Total Commander

1. Add global shortcut key. It's more convient to active total commander application with global shortcut key than pressing ctrl+tab sereval times. Though this can be achieved with tools like autohotkey, it's better if TC natively support global shortcut.

2. Improvement on command line. In windows console and linux shell, we can use tab key to complete file/command name. It's fabulous if TC also support this feature.

change command prompt font

Having used consolas font for a period, I felt very comfortable with it. I've used it in putty, vim, visual studio. And I tried to use it in windows console (cmd.exe) by following scott's post, Using Consolas as the Windows Console Font. But consolas font didn't show in console's available font list. It seemed to have to do with my console code page setting, which is 936 chinese gbk. Consolas was shown after I changed the console's code page to 850 with chcp command. Thing was not perfect, I could not use chinese input method under this code page in console, and chinese characters are not displayed correctly.
As a matter of fact, there is another way to set consolas font for console through registry, which doesn't require us to change code page. Our preferences for default console are saved in HKCU\Console, including console's width, height and font. Subitems of this key save preperences for console with specified title. So we can modify the FaceName item to force a font get applied. As shown below.

Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Console]
"FaceName"="Consolas"

[HKEY_CURRENT_USER\Console\%SystemRoot%_system32_cmd.exe]
"FaceName"="Consolas"

Here is a snapshot of the font comparison:

BTW, consolas font is designed specifically for ClearType. It looks extremely poor if ClearType is not enabled. We can use ClearType Tuner PowerToy to fine tune ClearType under windows xp.

References:
Necessary criteria for fonts to be available in a command window
Give Your Eyes a Treat

Use VI command in bash

If you are a fan of vi editor, you'll be exciting to find out that we can use vi command in shell.
By default, bash has its own set of short cut to make it easier to type and change command. But it's quite different from what we vi users have get used to. It's a pain to try to remember two different style of short cuts.
Fortunately, bash has the ability to allow us to retain our vi habit. To turn this feature on, simply run set -o vi . Then we can verify this feature is enabled by running set -o and see if it shows vi on.
Having turned it on, we can edit our commands just as in vi. By default, the shell is in insert mode. By pressing escape, it turns to command mode in which we can use vi command to move, search around.
For example, we can find a command in history by :

1. press escape
2. press /
3. input search terms
4. press n to search for next match

To view and edit shortcut keys in bash, we can use the bind build-in command.
Bonus: In windows prompt, we can use F7 to get a command history list and F8 to search in command history.

References:
Master the Linux bash command line with these 10 shortcuts
Useful Keyboard Shortcuts for the DOS Command Prompt in Windows
Find and bind key sequences in bash