chcp 65001 is utf-8

Reference:

http://stackoverflow.com/questions/1259084/what-encoding-code-page-is-cmd-exe-using

Activating UTF-8 in Windows Console: CHCP

   缺省情况下，C++ 以传值方式将对象传入或传出函数（这是一个从 C 继承来的特性）。除非你特别指定其它方式，否则函数的参数就会以实际参数（actual argument）的拷贝进行初始化，而函数的调用者会收到函数返回值的一个拷贝。这个拷贝由对象的拷贝构造函数生成。这就使得传值（pass-by- value）成为一个代价不菲的操作。例如，考虑下面这个类层级结构：

class Person { 　 public: 　　 Person(); // parameters omitted for simplicity 　　 virtual ~Person(); // see Item 7 for why this is virtual 　　 … 　 private: 　　 std::string name; 　　 std::string address; }; class Student: public Person { 　 public: 　　 Student(); // parameters again omitted 　　 ~Student(); 　　 … 　 private: 　　 std::string schoolName; 　　 std::string schoolAddress; };

    现在，考虑以下代码，在此我们调用一个函数―― validateStudent，它得到一个 Student 参数（以传值的方式），并返回它是否验证有效的结果：

bool validateStudent(Student s); // function taking a Student // by value Student plato; // Plato studied under Socrates bool platoIsOK = validateStudent(plato); // call the function

    当这个函数被调用时会发生什么呢？

　 　很明显，Student 的拷贝构造函数被调用，用 plato 来初始化参数 s。同样明显的是，当 validateStudent 返回时，s 就会被销毁。所以这个函数的参数传递代价是一次 Student 的拷贝构造函数的调用和一次 Student 的析构函数的调用。

　　 但这还不是全部。一个 Student 对象内部包含两个 string 对象，所以每次你构造一个 Student 对象的时候，你也必须构造两个 string 对象。一个 Student 对象还要从一个 Person 对象继承，所以每次你构造一个 Student 对象的时候，你也必须构造一个 Person 对象。一个 Person 对象内部又包含两个额外的 string 对象，所以每个 Person 的构造也承担着另外两个 string 的构造。最终，以传值方式传递一个 Student 对象的后果就是引起一次 Student 的拷贝构造函数的调用，一次 Person 的拷贝构造函数的调用，以及四次 string 的拷贝构造函数调用。当 Student 对象的拷贝被销毁时，每一个构造函数的调用都对应一个析构函数的调用，所以以传值方式传递一个 Student 的全部代价是六个构造函数和六个析构函数！

　　好了，这是正确的和值得的行为。毕竟，你希望你的全部对象都得到可靠的初始化和销毁。尽管如此，如果有一种办法可以绕过所有这些构造和析构过程，应该变得更好，这就是：传引用给 const（pass by   reference-to-const）：

bool validateStudent(const Student& s);

　 　这样做非常有效：没有任何构造函数和析构函数被调用，因为没有新的对象被构造。被修改的参数声明中的 const 是非常重要的。 validateStudent 的最初版本接受一个 Student 值参数，所以调用者知道它们屏蔽了函数对它们传入的 Student 的任何可能的改变；validateStudent 也只能改变它的一个拷贝。现在 Student 以引用方式传递，同时将它声明为 const 是必要的，否则调用者必然担心 validateStudent 改变了它们传入的 Student。

　　以传引用方式传递参数还可以避 免切断问题（slicing problem）。当一个派生类对象作为一个基类对象被传递（传值方式），基类的拷贝构造函数被调用，而那些使得对象的行为像一个派生类对象的特殊特性被 “切断”了。你只剩下一个纯粹的基类对象――这没什么可吃惊的，因为是一个基类的构造函数创建了它。这几乎绝不是你希望的。例如，假设你在一组实现一个图 形窗口系统的类上工作：

class Window { 　 public: 　　 … 　　 std::string name() const; // return name of window 　　 virtual void display() const; // draw window and contents }; class WindowWithScrollBars: public Window { 　 public: 　　 … 　　 virtual void display() const; };

    所有 Window 对象都有一个名字，你能通过 name 函数得到它，而且所有的窗口都可以显示，你可一个通过调用 display 函数来做到这一点。display 为 virtual 的事实清楚地告诉你：一个纯粹的基类的 Window 对象的显示方法有可能不同于专门的 WindowWithScrollBars 对象的显示方法。

　　现在，假设你想写一个函数打印出一个窗口的名字，并随后显示这个窗口。以下这个函数的写法是错误的：

void printNameAndDisplay(Window w) // incorrect! parameter { 　 // may be sliced! 　 std::cout << w.name(); 　 w.display(); }

    考虑当你用一个 WindowWithScrollBars 对象调用这个函数时会发生什么：

WindowWithScrollBars wwsb; printNameAndDisplay(wwsb);

    参数 w 将被作为一个 Window 对象构造――它是被传值的，记得吗？而且使 wwsb 表现得像一个 WindowWithScrollBars 对象的特殊信息都被切断了。在 printNameAndDisplay 中，全然不顾传递给函数的那个对象的类型，w 将始终表现得像一个 Window 类的对象（因为它就是一个 Window 类的对象）。特别是，在 printNameAndDisplay 中调用 display 将总是调用 Window：：display，绝不会是 WindowWithScrollBars：：display.

    绕过切断问题的方法就是以传引用给 const 的方式传递 w：

void printNameAndDisplay(const Window& w) // fine, parameter won’t { 　 // be sliced 　 std::cout << w.name(); 　 w.display(); }

    现在 w 将表现得像实际传入的那种窗口。

    如果你掀开编译器的盖头偷看一下，你会发现用指针实现引用是非常典型的做法，所以以引用传递某物实际上通常意味着传递一个指针。由此可以得出结论，如果你 有一个内建类型的对象（例如，一个 int），以传值方式传递它常常比传引用方式更高效。那么，对于内建类型，当你需要在传值和传引用给 const 之间做一个选择时，没有道理不选择传值。同样的建议也适用于 STL 中的迭代器（iterators）和函数对象（function objects），因为，作为惯例，它们就是为传值设计的。迭代器（iterators）和函数对象（function objects）的实现有责任保证拷贝的高效并且不受切断问题的影响。（这是一个”规则如何变化，依赖于你使用 C++ 的哪一个部分”的实例。）

    内建类型很小，所以有人就断定所有的小类型都是传值的上等候选者，即使它们是用户定义的。这样的推论是不可靠的。仅仅因为一个对象小，并不意味着调用它的 拷贝构造函数就是廉价的。很多对象――大多数 STL 容器也在其中――容纳的和指针一样，但是拷贝这样的对象必须同时拷贝它们指向的每一样东西。那可能是非常昂贵的。

    即使当一个小对象有一个廉价的拷贝构造函数，也会存在性能问题。一些编译器对内建类型和用户定义类型并不一视同仁，即使他们有同样的底层表示。例如，一些 编译器拒绝将仅由一个 double 组成的对象放入一个寄存器中，即使在常规上它们非常愿意将一个纯粹的 double 放入那里。如果发生了这种事情，你以传引用方式传递这样的对象更好一些，因为编译器理所当然会将一个指针（引用的实现）放入寄存器。

    小的用户定义类型不一定是传值的上等候选者的另一个原因是：作为用户定义类型，它的大小常常变化。一个现在较小的类型在将来版本中可能变得更大，因为它的 内部实现可能会变化。甚至当你换了一个不同的 C++ 实现时，事情都可能会变化。例如，就在我这样写的时候，一些标准库的 string 类型的实现的大小就是另外一些实现的七倍。

    通常情况下，你能合理地假设传值廉价的类型仅有内建类型及 STL 中的迭代器和函数对象类型。对其他任何类型，请遵循本 Item 的建议，并用传引用给 const 取代传值。

    Things to Remember

    。用传引用给 const 取代传值。典型情况下它更高效而且可以避免切断问题。

    。这条规则并不适用于内建类型及 STL 中的迭代器和函数对象类型。对于它们，传值通常更合适。

/*
 * const pointer issue:
 */
  const int * pa = &a; // pa points to a const int
  int const * pa2 = &a; // same as above
  const int * const cpa = &a; // cpa itself is a const pointer
                              // its value can't be changed

/***********************
 *   REFERENCE ISSUE   *
 ***********************/
/*
 * reference to a value, or to a expression,
 * or to another type must be const:
 */
double d = 2.0;
const int & i = d; // correct
int const & i2 =d; // correct

int const & i3 = 5; // correct

int a2 = 0;
int const & i4 = a2 + 1; // correct, a2+1 is a tmp value
int const * & a2r = &a2; // correct, because &a2 stores in a tmp place
             // so its reference must be const, in this case,
             // it's a const pointer to int

/*
 * const can't be applied on a reference variable:
 */
int & const i3 = d; // WRONG !!!
]]> http://klu2008.wordpress.com/2008/10/02/const-in-cc/feed/ 0 fei http://klu2008.wordpress.com/2008/09/04/life-in-text-mode/ http://klu2008.wordpress.com/2008/09/04/life-in-text-mode/#comments Thu, 04 Sep 2008 20:00:00 +0000 fei http://klu2008.wordpress.com/2008/09/04/life-in-text-mode/ ]]>

(Original post: http://aperiodic.net/phil/archives/Geekery/text-mode-guerrilla.html)

I primarily use Unix-based computers, mostly Linux. On those computers, I live in text mode. This entry is an attempt to document the software I find most useful to my text-mode guerrilla lifestyle. Included are links to the programs I rely on, links to alternative programs, and links to my config files.

screen (.screenrc, .screenrc-mithrandir). Simply indispensable. It slices and dices console sessions. Pretty much everything I do, I do in screen. For extensive details, see my ode to screen.

zsh (.zshrc, .zshenv, .zshprompt). My shell of choice. Think of all the good features of bash, ksh, and tcsh rolled together. (Without much of the ickiness, particularly the csh heritage.) Personally, the killer application of zsh was that fact that not only did it have context-sensitive completion but (unlike tcsh) it shipped with hordes of completion definitions right out of the box. Type 'dpkg -L fo<tab>' and zsh will autocomplete on the Debian packages currently installed on your system. With an ssh-agent running, type 'scp otherhost:fo<tab>' and zsh will ssh to the other system and autocomplete on the files available on that host.

irssi (config, theme). The best IRC client I've come across, certainly beating out IrcII, BitchX, and even epic. Multiple windows, extensible, tons of plugins available.

bitlbee. This is actually an IRC-to-Instant-Messaging gateway. It allows me to use AIM, Jabber, and the like from within my preferred chat program, irssi.

snownews. curses-based RSS aggregator. I shopped around a bit before finding an aggregator that I liked. snownews does everything I need.

mutt (.muttrc, config directory). Possibly the best mail client around, GUI or not. While pine is okay (and simpler to use), mutt is much more customizable and scales better to large volumes of email.

procmail (.procmailrc). Slices and dices my email. I have procmail rewriting things so they're easier for me to deal with, sorting my list mail into separate mailboxes (automatically; no need to add new lists by hand), and checking (and dealing with) spam. Essential to my email usage.

Emacs (.emacs). My text editor of choice. Feel free to substitute XEmacs or vi (preferably vim) at your own preference. I prefer emacs to vi, though I know a decent amount of vi, as any sysadmin should. I actually like XEmacs a little better than GNU Emacs, but GNU Emacs has better UTF-8 support.

w3m. Web browser. Among other things, w3m does tabbed browsing, though it's not multithreaded, so you can't read one tab while another is loading. It even has image support; run it with a valid $DISPLAY and it'll render images on the page. There are other text-mode browsers, most notably links. I'm not tremendously familiar with links because w3m fills all of my needs. (My original decision between the two came about because w3m had better HTML support, but I don't believe this is any longer the case.) The grandaddy of text-mode browsers is, of course, lynx, but it's lagged far behind w3m and links in support for newer aspects of HTML.

moosic (config). This is a music jukebox. The features that distinguish it from other such programs are twofold. First, it runs as a standalone server; you interact with it via a command line client. (In theory, a curses or GUI client could be written, but to my knowledge none yet has.) Second, it's customizable with regards to how it plays music. It has a config file where you tell it what programs to use to play various music formats (it does come with reasonable defaults). A program with similar design is mpd. mpd does its own music playing, which allows some advantages over moosic, but moosic has much better playlist management.

mplayer (config). Okay, this is kind of a hedge. I do indeed use it purely in text mode on occasion–it has better support for streaming media (usually mp3s) than any of the actual mp3 players I use. mplayer's main advantage is that it will play pretty much any video format I throw at it. (I'm not quite masochistic enough to watch the videos in aalib, though.)

surfraw (.surfraw.conf). surfraw is a collection of command-line based jumping-points to various web-based information, mostly searches. For a quick google search, I need only go to a command line and type 'sr google my search terms'. (Debian uses a single program, 'sr', as a wrapper for all of the surfraw "elvi". On other systems, you would probably just run 'google your search terms'.)

wget. The swiss-army-knife of grabbing things off the web (and via FTP). I've automated many downloads, some tweaked in interesting ways, with wget.

tdl. Completely command-line todo list manager. Along similar lines is DevTodo; I haven't really played with it because tdl does everything I need. Those two are both command-line based. For more of a todo list editor, you might want to take a look at hnb or woody. (Though, of those two, hnb has better support for todo lists.)

Those are the bigger programs that jump to mind most readily. I use a host of other programs, too. Listed briefly, they are: less (pager), mpg321 (mp3 player), GnuPG (OpenPGP implementation) (options), aumix (volume control), teTeX (TeX implementation), pal (nice colored calendar with a number of features), bc (simple command line calculator), dict (actually a dictionary network protocol but their command-line client is also named 'dict'), mp3gain (normalization of mp3s (ideally should be done non-destructively via ID3v2 but no one supports that)), netcat (connect directly to TCP sockets), BitTornado (bittorrent client; slightly nicer than the standard one), subversion (source revision control; nicer than cvs), abcde (CD ripper) (.abcde.conf), lame (MP3 encoder), nmap (portscanner), hping (packet generator), and tcpdump (packet sniffer).

I do normally run X; it lets me have multiple xterms on the screen at once. For managing those xterms, I run ion (config directory), a tiling window manager.

There are a couple of GUI programs I use regularly. I've already mentioned mplayer; you really need a pixelmapped interface to watch movies. There's also Ethereal, an excellent network sniffer and protocol analyzer (much nicer than plain tcpdump), and GnuCash, one of the best asset management programs I've come across. (But see clacct for straight command line checkbook balancing.) Oh, and Firefox, for those websites that just won't work with w3m.

Whether working on a server or a low end machine, you don’t want to bog things down even more by running a GUI — plus you need to know how to use the power of Linux and the GUI is just not it.

It is possible to accomplish most any task while working from within the shell. Having the knowledge of what and how to use the applications that are available is the key to being a successful CLI expert.

The following is a guide for the command line applications needed to work freely from within the Linux terminal. Now get off of your GUI butt, get typing, and throw your mouse in the trash.

Common Accessories

cmatrix

Screen Saver – cmatrix – Console matrix simulator. Use this with the - s option for screensaver mode. A must have for geeks.

Search – find – Find is default on most Linux distributions. Syntax is as follows: find /dir/name -name searchstring with many other options.

Printing – cat – Not the only way to use this command — The easiest way to print from CLI is by using the cat command to redirect the output directly to the printing device: cat filename | /dev/lpt1

Calculator – bc – Execute bc, enter your math equation and hit the enter key.

Midnight Commander

File Management – Midnight Commander – mc = Best.CLI.based.file.manger.eva Protocols include SMB, FTP, SSH, support along with the ability to browse ZIP and TAR files.

Text Editing and Development – nano – Easy to use text editor and clone of pico. Syntax highlighting is also available for various programming languages.

Spell Check – Ispell – Spell checking is essential if you care anything about what you write. Syntax is simple ispell file.txt.

Calendar – When – Very simple and effective calendar program.
 

Internet and File Transfer

Download Manager – Wget – Download manager and mirroring utility. Wget, hands down, is the best download manager for the Linux CLI.

Lynx Web Browser

Web Browser – Lynx – Simple and effective web browsing for command line.

FTP Client – NcFTP – Offers many enhancements over the classic ftp command.

Email Client – Mutt – Small and powerful email client with ability to use Lynx to read HTML emails.

BitTorrent Client – rtorrent – BitTorrent client based on libtorrent.

Chat Client – Finch – Text based version of the popular multi-client chat program Pidgin. It supports the same amount of protocols.

RSS Reader – rss2email – Automatically converts and sends RSS feeds to a specified email address. Also handles Atom feeds.

Podcatcher – BashPodder – Download your favorite podcasts.

Wifi Management – Kismet – Detects wireless access points, detect hidden access points, and do other things your mom never told you about.
 

Audio

mp3blaster

Audio Player – MP3blaster – plays OGG, MP3, and WAV files complete with playlists, shuffle, and repeat mode.

Audio Mixer – aumix – Scriptable command line audio mixer.

Audio Converter – SoX – SoX not only supports conversion, but also trimming, effects, and resampling. Known as the swiss army knife for audio files.

Audio Ripper – A Better CD Encoder – a.k.a. abcde rips audio CDs to the format that you specify. Abcde supports OGG, MP3, FLAC, SPX, and MPC.
 

Utilities

PDF Viewer – pdftohtml – For obvious reasons, reading PDFs in a CLI is not an option. Therefor, PDFs must be converted to a readable format such as HTML or text.

htop

Process Manager – htop – htop is similar to top, but with more features such as scrolling of the task list and colors. You need this managing and killing processes, troubleshooting system resource usage, etc.

bwm-ng

Bandwidth Monitor – bwm-ng – Next generation of bwm. Simple and effective.

To-do List – yaGTD – Getting things done application is perfect for to do lists and prioritization.

File Encryption – GPG – The GNU Privacy Guard is perfect for encrypting and decrypting sensitive information with a password.

Video Converter – MEncoder – Included with MPlayer, MEncoder has ability to convert video files between the following common formats: MPEG/VOB, AVI, ASF/WMA/WMV, RM, QT/MOV/MP4, Ogg/OGM, MKV, VIVO, FLI, and FLV.

Word File Viewer – Antiword – tired of everyone emailing .DOC files, don’t be.

The CLI is fun. If you plan on exploring deeper, check out Screen — the terminal multiplexor. There is so much you can do, and it is all at the power of your finger tips. I know that so much was missed in this article — only the most common applications are covered. Thanks to Linux.com’s CLI magic articles and the Ubuntu users list. Now you might have a clue how to get around when your X server crashes.

Have a command line application that deserves a spot here? Leave a comment or email me and I will add it to the list.

UPDATE: I found a similar page on aperiodic.net that might interest you.

]]> http://klu2008.wordpress.com/2008/09/04/linux-essential-command-line-apps-for-common-tasks/feed/ 0 fei Use the CLI CMatrix Midnight Commander Lynx MP3Blaster htop bwm-ng http://klu2008.wordpress.com/2008/09/04/linux%e4%b8%8b%e9%9d%9e%e5%b8%b8%e5%ae%9e%e7%94%a8%e7%9a%84%e5%91%bd%e4%bb%a4%e8%a1%8c%e5%b7%a5%e5%85%b7/ http://klu2008.wordpress.com/2008/09/04/linux%e4%b8%8b%e9%9d%9e%e5%b8%b8%e5%ae%9e%e7%94%a8%e7%9a%84%e5%91%bd%e4%bb%a4%e8%a1%8c%e5%b7%a5%e5%85%b7/#comments Thu, 04 Sep 2008 19:38:00 +0000 fei http://klu2008.wordpress.com/2008/09/04/linux%e4%b8%8b%e9%9d%9e%e5%b8%b8%e5%ae%9e%e7%94%a8%e7%9a%84%e5%91%bd%e4%bb%a4%e8%a1%8c%e5%b7%a5%e5%85%b7/ ]]> 2007-08-01  作者:bitsCN整理  来源:中国网管联盟

如果忘记了Ubuntu的用户名或是密码请按以下操作：

1，在启动的时候，上下移动，选中（不是按回车）类似这样的修复模式"Ubuntu-x.x.xx.xx-generic (recovery mode)，然后按e。

2，在第二层菜单选择有kernel这行，如："kernel /boot/vmlinux-x.x.xx-xx-generic root=UUID=ae424e-bod0-475c-2342433 ro single" 按下e进行编辑。

3，修改启动参数,将后面的ro single改为rw single init=/bin/bash，然后按回车。

如："kernel /boot/vmlinux-x.x.xx-xx-generic root=UUID=ae424e-bod0-475c-2342433 rw single init=/bin/bash"

4，按b启动系统就可以进入single模式而不需要密码了。

5，然后用passwd修改密码：具体命令是passwd 用户名。
]]> http://klu2008.wordpress.com/2008/09/03/ubuntu%e7%94%a8%e6%88%b7%e5%90%8d%e6%88%96%e5%af%86%e7%a0%81%e5%bf%98%e4%ba%86%e7%9a%84%e8%a7%a3%e5%86%b3%e6%96%b9%e6%a1%88/feed/ 0 fei http://klu2008.wordpress.com/2008/09/03/bash%e7%9a%84%e5%87%a0%e4%b8%aa%e5%88%9d%e5%a7%8b%e5%8c%96%e6%96%87%e4%bb%b6/ http://klu2008.wordpress.com/2008/09/03/bash%e7%9a%84%e5%87%a0%e4%b8%aa%e5%88%9d%e5%a7%8b%e5%8c%96%e6%96%87%e4%bb%b6/#comments Wed, 03 Sep 2008 15:50:00 +0000 fei http://klu2008.wordpress.com/2008/09/03/bash%e7%9a%84%e5%87%a0%e4%b8%aa%e5%88%9d%e5%a7%8b%e5%8c%96%e6%96%87%e4%bb%b6/ ]]> [日期：2008-09-01]     来源：Linux社区  作者：Jeicoe    

（1）/etc/profile

全局（公有）配置，不管是哪个用户，登录时都会读取该文件。

（2）/ect/bashrc

Ubuntu没有此文件，与之对应的是/ect/bash.bashrc

它也是全局（公有）的

bash执行时，不管是何种方式，都会读取此文件。

（3）~/.profile

若bash是以login方式执行时，读取~/.bash_profile，若它不存在，则读取~/.bash_login，若前两者不存在，读取~/.profile。

另外，图形模式登录时，此文件将被读取，即使存在~/.bash_profile和~/.bash_login。

（4）~/.bash_login

若bash是以login方式执行时，读取~/.bash_profile，若它不存在，则读取~/.bash_login，若前两者不存在，读取~/.profile。

（5）~/.bash_profile

Unbutu默认没有此文件，可新建。

只有bash是以login形式执行时，才会读取此文件。通常该配置文件还会配置成去读取~/.bashrc。

（6）~/.bashrc

当bash是以non-login形式执行时，读取此文件。若是以login形式执行，则不会读取此文件。

（7）~/.bash_logout

注销时，且是longin形式，此文件才会读取。也就是说，在文本模式注销时，此文件会被读取，图形模式注销时，此文件不会被读取。

下面是在本机的几个例子：

1. 图形模式登录时，顺序读取：/etc/profile和~/.profile

2. 图形模式登录后，打开终端时，顺序读取：/etc/bash.bashrc和~/.bashrc

3. 文本模式登录时，顺序读取：/etc/bash.bashrc，/etc/profile和~/.bash_profile

4. 从其它用户su到该用户，则分两种情况：

（1）如果带-l参数（或-参数，–login参数），如：su -l username，则bash是lonin的，它将顺序读取以下配置文件：/etc/bash.bashrc，/etc/profile和~/.bash_profile。

（2）如果没有带-l参数，则bash是non-login的，它将顺序读取：/etc/bash.bashrc和~/.bashrc

5. 注销时，或退出su登录的用户，如果是longin方式，那么bash会读取：~/.bash_logout

6. 执行自定义的shell文件时，若使用”bash -l a.sh”的方式，则bash会读取行：/etc/profile和~/.bash_profile，若使用其它方式，如：bash a.sh， ./a.sh，sh a.sh（这个不属于bash shell），则不会读取上面的任何文件。

7. 上面的例子凡是读取到~/.bash_profile的，若该文件不存在，则读取~/.bash_login，若前两者不存在，读取~/.profile。