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Flowsnow translating
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Apple Swift Programming Language Comes To Linux
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================================================================================
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Apple and Open Source toogether? Yes! Apple’s Swift programming language is now open source. This should not come as surprise because [Apple had already announced it six months back][1].
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Apple announced the launch of open source Swift community came this week. A [new website][2] dedicated to the open source Swift community has been put in place with the following message:
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> We are excited by this new chapter in the story of Swift. After Apple unveiled the Swift programming language, it quickly became one of the fastest growing languages in history. Swift makes it easy to write software that is incredibly fast and safe by design. Now that Swift is open source, you can help make the best general purpose programming language available everywhere.
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[swift.org][2] will work as the one stop shop providing downloads for various platforms, community guidelines, news, getting started tutorials, instructions for contribution to open source Swift, documentation and other guidelines. If you are looking forward to learn Swift, this website must be bookmarked.
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|
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In this announcement, a new package manager for easy sharing and building code has been made available as well.
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Most important of all for Linux users, the source code is now available at [Github][3]. You can check it out from the link below:
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- [Apple Swift Source Code][3]
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In addition to that, there are prebuilt binaries for Ubuntu 14.04 and 15.10.
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- [Swift binaries for Ubuntu][4]
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Don’t rush to use them because these are development branches and will not be suitable for production machine. So avoid it for now. Once stable version of Swift for Linux is released, I hope that Ubuntu will include it in [umake][5] on the line of [Visual Studio][6].
|
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--------------------------------------------------------------------------------
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via: http://itsfoss.com/swift-open-source-linux/
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作者：[Abhishek][a]
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译者：[译者ID](https://github.com/译者ID)
|
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校对：[校对者ID](https://github.com/校对者ID)
|
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|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
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[a]:http://itsfoss.com/author/abhishek/
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[1]:http://itsfoss.com/apple-open-sources-swift-programming-language-linux/
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[2]:https://swift.org/
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[3]:https://github.com/apple
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[4]:https://swift.org/download/#latest-development-snapshots
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[5]:https://wiki.ubuntu.com/ubuntu-make
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[6]:http://itsfoss.com/install-visual-studio-code-ubuntu/
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Translating by ZTinoZ
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7 ways hackers can use Wi-Fi against you
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================================================================================
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|
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### 7 ways hackers can use Wi-Fi against you ###
|
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|
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Wi-Fi — oh so convenient, yet oh so dangerous. Here are seven ways you could be giving away your identity through a Wi-Fi connection and what to do instead.
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|
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|
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### Using free hotspots ###
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They seem to be everywhere, and their numbers are expected to [quadruple over the next four years][1]. But many of them are untrustworthy, created just so your login credentials, to email or even more sensitive accounts, can be picked up by hackers using “sniffers” — software that captures any information you submit over the connection. The best defense against sniffing hackers is to use a VPN (virtual private network). A VPN keeps your private data protected because it encrypts what you input.
|
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|
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|
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|
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### Banking online ###
|
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|
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You might think that no one needs to be warned against banking online using free Wi-Fi, but cybersecurity firm Kaspersky Lab says that [more than 100 banks worldwide have lost $900 million][2] from cyberhacking, so it would seem that a lot of people are doing it. If you want to use the free Wi-Fi in a coffee shop because you’re confident it will be legitimate, confirm the exact network name with the barista. It’s pretty easy for [someone else in the shop with a router to set up an open connection][3] with a name that seems like it would be the name of the shop’s Wi-Fi.
|
||||
|
||||
|
||||
|
||||
### Keeping Wi-Fi on all the time ###
|
||||
|
||||
When your phone’s Wi-Fi is automatically enabled, you can be connected to an unsecure network without even realizing it. Use your phone’s [location-based Wi-Fi feature][4], if it’s available. It will turn off your Wi-Fi when you’re away from your saved networks and will turn back on when you’re within range.
|
||||
|
||||
|
||||
|
||||
### Not using a firewall ###
|
||||
|
||||
A firewall is your first line of defense against malicious intruders. It’s meant to let good traffic through your computer on a network and keep hackers and malware out. You should turn it off only when your antivirus software has its own firewall.
|
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|
||||
|
||||
|
||||
### Browsing unencrypted websites ###
|
||||
|
||||
Sad to say, [55% of the Web’s top 1 million sites don’t offer encryption][5]. An unencrypted website allows all data transmissions to be viewed by the prying eyes of hackers. Your browser will indicate when a site is secure (you’ll see a gray padlock with Mozilla Firefox, for example, and a green lock icon with Chrome). But even a secure website can’t protect you from sidejackers, who can steal the cookies from a website you visited, whether it’s a valid site or not, through a public network.
|
||||
|
||||
|
||||
|
||||
### Not updating your security software ###
|
||||
|
||||
If you want to ensure that your own network is well protected, upgrade the firmware of your router. All you have to do is go to your router’s administration page to check. Normally, you can download the newest firmware right from the manufacturer’s site.
|
||||
|
||||
|
||||
|
||||
### Not securing your home Wi-Fi ###
|
||||
|
||||
Needless to say, it is important to set up a password that is not too easy to guess, and change your connection’s default name. You can also filter your MAC address so your router will recognize only certain devices.
|
||||
|
||||
**Josh Althuser** is an open software advocate, Web architect and tech entrepreneur. Over the past 12 years, he has spent most of his time advocating for open-source software and managing teams and projects, as well as providing enterprise-level consultancy for Web applications and helping bring their products to the market. You may connect with him on [Twitter][6].
|
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|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: http://www.networkworld.com/article/3003170/mobile-security/7-ways-hackers-can-use-wi-fi-against-you.html
|
||||
|
||||
作者：[Josh Althuser][a]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://twitter.com/JoshAlthuser
|
||||
[1]:http://www.pcworld.com/article/243464/number_of_wifi_hotspots_to_quadruple_by_2015_says_study.html
|
||||
[2]:http://www.nytimes.com/2015/02/15/world/bank-hackers-steal-millions-via-malware.html?hp&action=click&pgtype=Homepage&module=first-column-region%C2%AEion=top-news&WT.nav=top-news&_r=3
|
||||
[3]:http://news.yahoo.com/blogs/upgrade-your-life/banking-online-not-hacked-182159934.html
|
||||
[4]:http://pocketnow.com/2014/10/15/should-you-leave-your-smartphones-wifi-on-or-turn-it-off
|
||||
[5]:http://www.cnet.com/news/chrome-becoming-tool-in-googles-push-for-encrypted-web/
|
||||
[6]:https://twitter.com/JoshAlthuser
|
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translating。。。
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Review: 5 memory debuggers for Linux coding
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================================================================================
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|
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Credit: [Moini][1]
|
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|
||||
As a programmer, I'm aware that I tend to make mistakes -- and why not? Even programmers are human. Some errors are detected during code compilation, while others get caught during software testing. However, a category of error exists that usually does not get detected at either of these stages and that may cause the software to behave unexpectedly -- or worse, terminate prematurely.
|
||||
|
||||
If you haven't already guessed it, I am talking about memory-related errors. Manually debugging these errors can be not only time-consuming but difficult to find and correct. Also, it's worth mentioning that these errors are surprisingly common, especially in software written in programming languages like C and C++, which were designed for use with [manual memory management][2].
|
||||
|
||||
Thankfully, several programming tools exist that can help you find memory errors in your software programs. In this roundup, I assess five popular, free and open-source memory debuggers that are available for Linux: Dmalloc, Electric Fence, Memcheck, Memwatch and Mtrace. I've used all five in my day-to-day programming, and so these reviews are based on practical experience.
|
||||
|
||||
eviews are based on practical experience.
|
||||
|
||||
### [Dmalloc][3] ###
|
||||
|
||||
**Developer**: Gray Watson
|
||||
**Reviewed version**: 5.5.2
|
||||
**Linux support**: All flavors
|
||||
**License**: Creative Commons Attribution-Share Alike 3.0 License
|
||||
|
||||
Dmalloc is a memory-debugging tool developed by Gray Watson. It is implemented as a library that provides wrappers around standard memory management functions like **malloc(), calloc(), free()** and more, enabling programmers to detect problematic code.
|
||||
|
||||
|
||||
Dmalloc
|
||||
|
||||
As listed on the tool's Web page, the debugging features it provides includes memory-leak tracking, [double free][4] error tracking and [fence-post write detection][5]. Other features include file/line number reporting, and general logging of statistics.
|
||||
|
||||
#### What's new ####
|
||||
|
||||
Version 5.5.2 is primarily a [bug-fix release][6] containing corrections for a couple of build and install problems.
|
||||
|
||||
#### What's good about it ####
|
||||
|
||||
The best part about Dmalloc is that it's extremely configurable. For example, you can configure it to include support for C++ programs as well as threaded applications. A useful functionality it provides is runtime configurability, which means that you can easily enable/disable the features the tool provides while it is being executed.
|
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|
||||
You can also use Dmalloc with the [GNU Project Debugger (GDB)][7] -- just add the contents of the dmalloc.gdb file (located in the contrib subdirectory in Dmalloc's source package) to the .gdbinit file in your home directory.
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|
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Another thing that I really like about Dmalloc is its extensive documentation. Just head to the [documentation section][8] on its official website, and you'll get everything from how to download, install, run and use the library to detailed descriptions of the features it provides and an explanation of the output file it produces. There's also a section containing solutions to some common problems.
|
||||
|
||||
#### Other considerations ####
|
||||
|
||||
Like Mtrace, Dmalloc requires programmers to make changes to their program's source code. In this case you may, at the very least, want to add the **dmalloc.h** header, because it allows the tool to report the file/line numbers of calls that generate problems, something that is very useful as it saves time while debugging.
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|
||||
In addition, the Dmalloc library, which is produced after the package is compiled, needs to be linked with your program while the program is being compiled.
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||||
However, complicating things somewhat is the fact that you also need to set an environment variable, dubbed **DMALLOC_OPTION**, that the debugging tool uses to configure the memory debugging features -- as well as the location of the output file -- at runtime. While you can manually assign a value to the environment variable, beginners may find that process a bit tough, given that the Dmalloc features you want to enable are listed as part of that value, and are actually represented as a sum of their respective hexadecimal values -- you can read more about it [here][9].
|
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|
||||
An easier way to set the environment variable is to use the [Dmalloc Utility Program][10], which was designed for just that purpose.
|
||||
|
||||
#### Bottom line ####
|
||||
|
||||
Dmalloc's real strength lies in the configurability options it provides. It is also highly portable, having being successfully ported to many OSes, including AIX, BSD/OS, DG/UX, Free/Net/OpenBSD, GNU/Hurd, HPUX, Irix, Linux, MS-DOG, NeXT, OSF, SCO, Solaris, SunOS, Ultrix, Unixware and even Unicos (on a Cray T3E). Although the tool has a bit of a learning curve associated with it, the features it provides are worth it.
|
||||
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||||
### [Electric Fence][15] ###
|
||||
|
||||
**Developer**: Bruce Perens
|
||||
**Reviewed version**: 2.2.3
|
||||
**Linux support**: All flavors
|
||||
**License**: GNU GPL (version 2)
|
||||
|
||||
Electric Fence is a memory-debugging tool developed by Bruce Perens. It is implemented in the form of a library that your program needs to link to, and is capable of detecting overruns of memory allocated on a [heap][11] ) as well as memory accesses that have already been released.
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||||
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||||
Electric Fence
|
||||
|
||||
As the name suggests, Electric Fence creates a virtual fence around each allocated buffer in a way that any illegal memory access results in a [segmentation fault][12]. The tool supports both C and C++ programs.
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|
||||
#### What's new ####
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||||
|
||||
Version 2.2.3 contains a fix for the tool's build system, allowing it to actually pass the -fno-builtin-malloc option to the [GNU Compiler Collection (GCC)][13].
|
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|
||||
#### What's good about it ####
|
||||
|
||||
The first thing that I liked about Electric Fence is that -- unlike Memwatch, Dmalloc and Mtrace -- it doesn't require you to make any changes in the source code of your program. You just need to link your program with the tool's library during compilation.
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Secondly, the way the debugging tool is implemented makes sure that a segmentation fault is generated on the very first instruction that causes a bounds violation, which is always better than having the problem detected at a later stage.
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Electric Fence always produces a copyright message in output irrespective of whether an error was detected or not. This behavior is quite useful, as it also acts as a confirmation that you are actually running an Electric Fence-enabled version of your program.
|
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|
||||
#### Other considerations ####
|
||||
|
||||
On the other hand, what I really miss in Electric Fence is the ability to detect memory leaks, as it is one of the most common and potentially serious problems that software written in C/C++ has. In addition, the tool cannot detect overruns of memory allocated on the stack, and is not thread-safe.
|
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|
||||
Given that the tool allocates an inaccessible virtual memory page both before and after a user-allocated memory buffer, it ends up consuming a lot of extra memory if your program makes too many dynamic memory allocations.
|
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|
||||
Another limitation of the tool is that it cannot explicitly tell exactly where the problem lies in your programs' code -- all it does is produce a segmentation fault whenever it detects a memory-related error. To find out the exact line number, you'll have to debug your Electric Fence-enabled program with a tool like [The Gnu Project Debugger (GDB)][14], which in turn depends on the -g compiler option to produce line numbers in output.
|
||||
|
||||
Finally, although Electric Fence is capable of detecting most buffer overruns, an exception is the scenario where the allocated buffer size is not a multiple of the word size of the system -- in that case, an overrun (even if it's only a few bytes) won't be detected.
|
||||
|
||||
#### Bottom line ####
|
||||
|
||||
Despite all its limitations, where Electric Fence scores is the ease of use -- just link your program with the tool once, and it'll alert you every time it detects a memory issue it's capable of detecting. However, as already mentioned, the tool requires you to use a source-code debugger like GDB.
|
||||
|
||||
### [Memcheck][16] ###
|
||||
|
||||
**Developer**: [Valgrind Developers][17]
|
||||
**Reviewed version**: 3.10.1
|
||||
**Linux support**: All flavors
|
||||
**License**: GPL
|
||||
|
||||
[Valgrind][18] is a suite that provides several tools for debugging and profiling Linux programs. Although it works with programs written in many different languages -- such as Java, Perl, Python, Assembly code, Fortran, Ada and more -- the tools it provides are largely aimed at programs written in C and C++.
|
||||
|
||||
The most popular Valgrind tool is Memcheck, a memory-error detector that can detect issues such as memory leaks, invalid memory access, uses of undefined values and problems related to allocation and deallocation of heap memory.
|
||||
|
||||
#### What's new ####
|
||||
|
||||
This [release][19] of the suite (3.10.1) is a minor one that primarily contains fixes to bugs reported in version 3.10.0. In addition, it also "backports fixes for all reported missing AArch64 ARMv8 instructions and syscalls from the trunk."
|
||||
|
||||
#### What's good about it ####
|
||||
|
||||
Memcheck, like all other Valgrind tools, is basically a command line utility. It's very easy to use: If you normally run your program on the command line in a form such as prog arg1 arg2, you just need to add a few values, like this: valgrind --leak-check=full prog arg1 arg2.
|
||||
|
||||
|
||||
Memcheck
|
||||
|
||||
(Note: You don't need to mention Memcheck anywhere in the command line because it's the default Valgrind tool. However, you do need to initially compile your program with the -g option -- which adds debugging information -- so that Memcheck's error messages include exact line numbers.)
|
||||
|
||||
What I really like about Memcheck is that it provides a lot of command line options (such as the --leak-check option mentioned above), allowing you to not only control how the tool works but also how it produces the output.
|
||||
|
||||
For example, you can enable the --track-origins option to see information on the sources of uninitialized data in your program. Enabling the --show-mismatched-frees option will let Memcheck match the memory allocation and deallocation techniques. For code written in C language, Memcheck will make sure that only the free() function is used to deallocate memory allocated by malloc(), while for code written in C++, the tool will check whether or not the delete and delete[] operators are used to deallocate memory allocated by new and new[], respectively. If a mismatch is detected, an error is reported.
|
||||
|
||||
But the best part, especially for beginners, is that the tool even produces suggestions about which command line option the user should use to make the output more meaningful. For example, if you do not use the basic --leak-check option, it will produce an output suggesting: "Rerun with --leak-check=full to see details of leaked memory." And if there are uninitialized variables in the program, the tool will generate a message that says, "Use --track-origins=yes to see where uninitialized values come from."
|
||||
|
||||
Another useful feature of Memcheck is that it lets you [create suppression files][20], allowing you to suppress certain errors that you can't fix at the moment -- this way you won't be reminded of them every time the tool is run. It's worth mentioning that there already exists a default suppression file that Memcheck reads to suppress errors in the system libraries, such as the C library, that come pre-installed with your OS. You can either create a new suppression file for your use, or edit the existing one (usually /usr/lib/valgrind/default.supp).
|
||||
|
||||
For those seeking advanced functionality, it's worth knowing that Memcheck can also [detect memory errors][21] in programs that use [custom memory allocators][22]. In addition, it also provides [monitor commands][23] that can be used while working with Valgrind's built-in gdbserver, as well as a [client request mechanism][24] that allows you not only to tell the tool facts about the behavior of your program, but make queries as well.
|
||||
|
||||
#### Other considerations ####
|
||||
|
||||
While there's no denying that Memcheck can save you a lot of debugging time and frustration, the tool uses a lot of memory, and so can make your program execution significantly slower (around 20 to 30 times, [according to the documentation][25]).
|
||||
|
||||
Aside from this, there are some other limitations, too. According to some user comments, Memcheck apparently isn't [thread-safe][26]; it doesn't detect [static buffer overruns][27]). Also, there are some Linux programs, like [GNU Emacs][28], that currently do not work with Memcheck.
|
||||
|
||||
If you're interested in taking a look, an exhaustive list of Valgrind's limitations can be found [here][29].
|
||||
|
||||
#### Bottom line ####
|
||||
|
||||
Memcheck is a handy memory-debugging tool for both beginners as well as those looking for advanced features. While it's very easy to use if all you need is basic debugging and error checking, there's a bit of learning curve if you want to use features like suppression files or monitor commands.
|
||||
|
||||
Although it has a long list of limitations, Valgrind (and hence Memcheck) claims on its site that it is used by [thousands of programmers][30] across the world -- the team behind the tool says it's received feedback from users in over 30 countries, with some of them working on projects with up to a whopping 25 million lines of code.
|
||||
|
||||
### [Memwatch][31] ###
|
||||
|
||||
**Developer**: Johan Lindh
|
||||
**Reviewed version**: 2.71
|
||||
**Linux support**: All flavors
|
||||
**License**: GNU GPL
|
||||
|
||||
Memwatch is a memory-debugging tool developed by Johan Lindh. Although it's primarily a memory-leak detector, it is also capable (according to its Web page) of detecting other memory-related issues like [double-free error tracking and erroneous frees][32], buffer overflow and underflow, [wild pointer][33] writes, and more.
|
||||
|
||||
The tool works with programs written in C. Although you can also use it with C++ programs, it's not recommended (according to the Q&A file that comes with the tool's source package).
|
||||
|
||||
#### What's new ####
|
||||
|
||||
This version adds ULONG_LONG_MAX to detect whether a program is 32-bit or 64-bit.
|
||||
|
||||
#### What's good about it ####
|
||||
|
||||
Like Dmalloc, Memwatch comes with good documentation. You can refer to the USING file if you want to learn things like how the tool works; how it performs initialization, cleanup and I/O operations; and more. Then there is a FAQ file that is aimed at helping users in case they face any common error while using Memcheck. Finally, there is a test.c file that contains a working example of the tool for your reference.
|
||||
|
||||
|
||||
Memwatch
|
||||
|
||||
Unlike Mtrace, the log file to which Memwatch writes the output (usually memwatch.log) is in human-readable form. Also, instead of truncating, Memwatch appends the memory-debugging output to the file each time the tool is run, allowing you to easily refer to the previous outputs should the need arise.
|
||||
|
||||
It's also worth mentioning that when you execute your program with Memwatch enabled, the tool produces a one-line output on [stdout][34] informing you that some errors were found -- you can then head to the log file for details. If no such error message is produced, you can rest assured that the log file won't contain any mistakes -- this actually saves time if you're running the tool several times.
|
||||
|
||||
Another thing that I liked about Memwatch is that it also provides a way through which you can capture the tool's output from within the code, and handle it the way you like (refer to the mwSetOutFunc() function in the Memwatch source code for more on this).
|
||||
|
||||
#### Other considerations ####
|
||||
|
||||
Like Mtrace and Dmalloc, Memwatch requires you to add extra code to your source file -- you have to include the memwatch.h header file in your code. Also, while compiling your program, you need to either compile memwatch.c along with your program's source files or include the object module from the compile of the file, as well as define the MEMWATCH and MW_STDIO variables on the command line. Needless to say, the -g compiler option is also required for your program if you want exact line numbers in the output.
|
||||
|
||||
There are some features that it doesn't contain. For example, the tool cannot detect attempts to write to an address that has already been freed or read data from outside the allocated memory. Also, it's not thread-safe. Finally, as I've already pointed out in the beginning, there is no guarantee on how the tool will behave if you use it with programs written in C++.
|
||||
|
||||
#### Bottom line ####
|
||||
|
||||
Memcheck can detect many memory-related problems, making it a handy debugging tool when dealing with projects written in C. Given that it has a very small source code, you can learn how the tool works, debug it if the need arises, and even extend or update its functionality as per your requirements.
|
||||
|
||||
### [Mtrace][35] ###
|
||||
|
||||
**Developers**: Roland McGrath and Ulrich Drepper
|
||||
**Reviewed version**: 2.21
|
||||
**Linux support**: All flavors
|
||||
**License**: GNU LGPL
|
||||
|
||||
Mtrace is a memory-debugging tool included in [the GNU C library][36]. It works with both C and C++ programs on Linux, and detects memory leaks caused by unbalanced calls to the malloc() and free() functions.
|
||||
|
||||
|
||||
Mtrace
|
||||
|
||||
The tool is implemented in the form of a function called mtrace(), which traces all malloc/free calls made by a program and logs the information in a user-specified file. Because the file contains data in computer-readable format, a Perl script -- also named mtrace -- is used to convert and display it in human-readable form.
|
||||
|
||||
#### What's new ####
|
||||
|
||||
[The Mtrace source][37] and [the Perl file][38] that now come with the GNU C library (version 2.21) add nothing new to the tool aside from an update to the copyright dates.
|
||||
|
||||
#### What's good about it ####
|
||||
|
||||
The best part about Mtrace is that the learning curve for it isn't steep; all you need to understand is how and where to add the mtrace() -- and the corresponding muntrace() -- function in your code, and how to use the Mtrace Perl script. The latter is very straightforward -- all you have to do is run the mtrace() <program-executable> <log-file-generated-upon-program-execution> command. (For an example, see the last command in the screenshot above.)
|
||||
|
||||
Another thing that I like about Mtrace is that it's scalable -- which means that you can not only use it to debug a complete program, but can also use it to detect memory leaks in individual modules of the program. Just call the mtrace() and muntrace() functions within each module.
|
||||
|
||||
Finally, since the tool is triggered when the mtrace() function -- which you add in your program's source code -- is executed, you have the flexibility to enable the tool dynamically (during program execution) [using signals][39].
|
||||
|
||||
#### Other considerations ####
|
||||
|
||||
Because the calls to mtrace() and mauntrace() functions -- which are declared in the mcheck.h file that you need to include in your program's source -- are fundamental to Mtrace's operation (the mauntrace() function is not [always required][40]), the tool requires programmers to make changes in their code at least once.
|
||||
|
||||
Be aware that you need to compile your program with the -g option (provided by both the [GCC][41] and [G++][42] compilers), which enables the debugging tool to display exact line numbers in the output. In addition, some programs (depending on how big their source code is) can take a long time to compile. Finally, compiling with -g increases the size of the executable (because it produces extra information for debugging), so you have to remember that the program needs to be recompiled without -g after the testing has been completed.
|
||||
|
||||
To use Mtrace, you need to have some basic knowledge of environment variables in Linux, given that the path to the user-specified file -- which the mtrace() function uses to log all the information -- has to be set as a value for the MALLOC_TRACE environment variable before the program is executed.
|
||||
|
||||
Feature-wise, Mtrace is limited to detecting memory leaks and attempts to free up memory that was never allocated. It can't detect other memory-related issues such as illegal memory access or use of uninitialized memory. Also, [there have been complaints][43] that it's not [thread-safe][44].
|
||||
|
||||
### Conclusions ###
|
||||
|
||||
Needless to say, each memory debugger that I've discussed here has its own qualities and limitations. So, which one is best suited for you mostly depends on what features you require, although ease of setup and use might also be a deciding factor in some cases.
|
||||
|
||||
Mtrace is best suited for cases where you just want to catch memory leaks in your software program. It can save you some time, too, since the tool comes pre-installed on your Linux system, something which is also helpful in situations where the development machines aren't connected to the Internet or you aren't allowed to download a third party tool for any kind of debugging.
|
||||
|
||||
Dmalloc, on the other hand, can not only detect more error types compared to Mtrace, but also provides more features, such as runtime configurability and GDB integration. Also, unlike any other tool discussed here, Dmalloc is thread-safe. Not to mention that it comes with detailed documentation, making it ideal for beginners.
|
||||
|
||||
Although Memwatch comes with even more comprehensive documentation than Dmalloc, and can detect even more error types, you can only use it with software written in the C programming language. One of its features that stands out is that it lets you handle its output from within the code of your program, something that is helpful in case you want to customize the format of the output.
|
||||
|
||||
If making changes to your program's source code is not what you want, you can use Electric Fence. However, keep in mind that it can only detect a couple of error types, and that doesn't include memory leaks. Plus, you also need to know GDB basics to make the most out of this memory-debugging tool.
|
||||
|
||||
Memcheck is probably the most comprehensive of them all. It detects more error types and provides more features than any other tool discussed here -- and it doesn't require you to make any changes in your program's source code.But be aware that, while the learning curve is not very high for basic usage, if you want to use its advanced features, a level of expertise is definitely required.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: http://www.computerworld.com/article/3003957/linux/review-5-memory-debuggers-for-linux-coding.html
|
||||
|
||||
作者：[Himanshu Arora][a]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:http://www.computerworld.com/author/Himanshu-Arora/
|
||||
[1]:https://openclipart.org/detail/132427/penguin-admin
|
||||
[2]:https://en.wikipedia.org/wiki/Manual_memory_management
|
||||
[3]:http://dmalloc.com/
|
||||
[4]:https://www.owasp.org/index.php/Double_Free
|
||||
[5]:https://stuff.mit.edu/afs/sipb/project/gnucash-test/src/dmalloc-4.8.2/dmalloc.html#Fence-Post%20Overruns
|
||||
[6]:http://dmalloc.com/releases/notes/dmalloc-5.5.2.html
|
||||
[7]:http://www.gnu.org/software/gdb/
|
||||
[8]:http://dmalloc.com/docs/
|
||||
[9]:http://dmalloc.com/docs/latest/online/dmalloc_26.html#SEC32
|
||||
[10]:http://dmalloc.com/docs/latest/online/dmalloc_23.html#SEC29
|
||||
[11]:https://en.wikipedia.org/wiki/Memory_management#Dynamic_memory_allocation
|
||||
[12]:https://en.wikipedia.org/wiki/Segmentation_fault
|
||||
[13]:https://en.wikipedia.org/wiki/GNU_Compiler_Collection
|
||||
[14]:http://www.gnu.org/software/gdb/
|
||||
[15]:https://launchpad.net/ubuntu/+source/electric-fence/2.2.3
|
||||
[16]:http://valgrind.org/docs/manual/mc-manual.html
|
||||
[17]:http://valgrind.org/info/developers.html
|
||||
[18]:http://valgrind.org/
|
||||
[19]:http://valgrind.org/docs/manual/dist.news.html
|
||||
[20]:http://valgrind.org/docs/manual/mc-manual.html#mc-manual.suppfiles
|
||||
[21]:http://valgrind.org/docs/manual/mc-manual.html#mc-manual.mempools
|
||||
[22]:http://stackoverflow.com/questions/4642671/c-memory-allocators
|
||||
[23]:http://valgrind.org/docs/manual/mc-manual.html#mc-manual.monitor-commands
|
||||
[24]:http://valgrind.org/docs/manual/mc-manual.html#mc-manual.clientreqs
|
||||
[25]:http://valgrind.org/docs/manual/valgrind_manual.pdf
|
||||
[26]:http://sourceforge.net/p/valgrind/mailman/message/30292453/
|
||||
[27]:https://msdn.microsoft.com/en-us/library/ee798431%28v=cs.20%29.aspx
|
||||
[28]:http://www.computerworld.com/article/2484425/linux/5-free-linux-text-editors-for-programming-and-word-processing.html?nsdr=true&page=2
|
||||
[29]:http://valgrind.org/docs/manual/manual-core.html#manual-core.limits
|
||||
[30]:http://valgrind.org/info/
|
||||
[31]:http://www.linkdata.se/sourcecode/memwatch/
|
||||
[32]:http://www.cecalc.ula.ve/documentacion/tutoriales/WorkshopDebugger/007-2579-007/sgi_html/ch09.html
|
||||
[33]:http://c2.com/cgi/wiki?WildPointer
|
||||
[34]:https://en.wikipedia.org/wiki/Standard_streams#Standard_output_.28stdout.29
|
||||
[35]:http://www.gnu.org/software/libc/manual/html_node/Tracing-malloc.html
|
||||
[36]:https://www.gnu.org/software/libc/
|
||||
[37]:https://sourceware.org/git/?p=glibc.git;a=history;f=malloc/mtrace.c;h=df10128b872b4adc4086cf74e5d965c1c11d35d2;hb=HEAD
|
||||
[38]:https://sourceware.org/git/?p=glibc.git;a=history;f=malloc/mtrace.pl;h=0737890510e9837f26ebee2ba36c9058affb0bf1;hb=HEAD
|
||||
[39]:http://webcache.googleusercontent.com/search?q=cache:s6ywlLtkSqQJ:www.gnu.org/s/libc/manual/html_node/Tips-for-the-Memory-Debugger.html+&cd=1&hl=en&ct=clnk&gl=in&client=Ubuntu
|
||||
[40]:http://www.gnu.org/software/libc/manual/html_node/Using-the-Memory-Debugger.html#Using-the-Memory-Debugger
|
||||
[41]:http://linux.die.net/man/1/gcc
|
||||
[42]:http://linux.die.net/man/1/g++
|
||||
[43]:https://sourceware.org/ml/libc-help/2014-05/msg00008.html
|
||||
[44]:https://en.wikipedia.org/wiki/Thread_safety
|
||||
@ -1,95 +0,0 @@
|
||||
alim0x translating
|
||||
|
||||
The history of Android
|
||||
================================================================================
|
||||
|
||||
Another Market design that was nothing like the old one. This lineup shows the categories page, featured, a top apps list, and an app page.
|
||||
Photo by Ron Amadeo
|
||||
|
||||
These screenshots give us our first look at the refined version of the Action Bar in Ice Cream Sandwich. Almost every app got a bar at the top of the screen that housed the app icon, title of the screen, several function buttons, and a menu button on the right. The right-aligned menu button was called the "overflow" button, because it housed items that didn't fit on the main action bar. The overflow menu wasn't static, though, it gave the action bar more screen real-estate—like in horizontal mode or on a tablet—and more of the overflow menu items were shown on the action bar as actual buttons.
|
||||
|
||||
New in Ice Cream Sandwich was this design style of "swipe tabs," which replaced the 2×3 interstitial navigation screen Google was previously pushing. A tab bar sat just under the Action Bar, with the center title showing the current tab and the left and right having labels for the pages to the left and right of this screen. A swipe in either direction would change tabs, or you could tap on a title to go to that tab.
|
||||
|
||||
One really cool design touch on the individual app screen was that, after the pictures, it would dynamically rearrange the page based on your history with that app. If you never installed the app before, the description would be the first box. If you used the app before, the first section would be the reviews bar, which would either invite you to review the app or remind you what you thought of the app last time you installed it. The second section for a previously used app was “What’s New," since an existing user would most likely be interested in changes.
|
||||
|
||||
|
||||
Recent apps and the browser were just like Honeycomb, but smaller.
|
||||
Photo by Ron Amadeo
|
||||
|
||||
Recent apps toned the Tron look way down. The blue outline around the thumbnails was removed, along with the eerie, uneven blue glow in the background. It now looked like a neutral UI piece that would be at home in any time period.
|
||||
|
||||
The Browser did its best to bring a tabbed experience to phones. Multi-tab browsing was placed front and center, but instead of wasting precious screen space on a tab strip, a tab button would open a Recent Apps-like interface that would show you your open tabs. Functionally, there wasn't much difference between this and the "window" view that was present in past versions of the Browser. The best addition to the Browser was a "Request desktop site" menu item, which would switch from the default mobile view to the normal site. The Browser showed off the flexibility of Google's Action Bar design, which, despite not having a top-left app icon, still functioned like any other top bar design.
|
||||
|
||||
|
||||
Gmail and Google Talk—they're like Honeycomb, but smaller!
|
||||
Photo by Ron Amadeo
|
||||
|
||||
Gmail and Google Talk both looked like smaller versions of their Honeycomb designs, but with a few tweaks to work better on smaller screens. Gmail featured a dual Action Bar—one on the top of the screen and one on the bottom. The top of the bar showed your current folder, account, and number of unread messages, and tapping on the bar opened a navigation menu. The bottom featured all the normal buttons you would expect along with the overflow button. This dual layout was used in order display more buttons on the surface level, but in landscape mode where vertical space was at a premium, the dual bars merged into a single top bar.
|
||||
|
||||
In the message view, the blue bar was "sticky" when you scrolled down. It stuck to the top of the screen, so you could always see who wrote the current message, reply, or star it. Once in a message, the thin, dark gray bar at the bottom showed your current spot in the inbox (or whatever list brought you here), and you could swipe left and right to get to other messages.
|
||||
|
||||
Google Talk would let you swipe left and right to change chat windows, just like Gmail, but there the bar was at the top.
|
||||
|
||||
|
||||
The new dialer and the incoming call screen, both of which we haven't seen since Gingerbread.
|
||||
Photo by Ron Amadeo
|
||||
|
||||
Since Honeycomb was only for tablets, some UI pieces were directly preceded by Gingerbread instead. The new Ice Cream Sandwich dialer was, of course, black and blue, and it used smaller tabs that could be swiped through. While Ice Cream Sandwich finally did the sensible thing and separated the main phone and contacts interfaces, the phone app still had its own contacts tab. There were now two spots to view your contact list—one with a dark theme and one with a light theme. With a hardware search button no longer being a requirement, the bottom row of buttons had the voicemail shortcut swapped out for a search icon.
|
||||
|
||||
Google liked to have the incoming call interface mirror the lock screen, which meant Ice Cream Sandwich got a circle-unlock design. Besides the usual decline or accept options, a new button was added to the top of the circle, which would let you decline a call by sending a pre-defined text message to the caller. Swiping up and picking a message like "Can't talk now, call you later" was (and still is) much more informative than an endlessly ringing phone.
|
||||
|
||||
|
||||
Honeycomb didn't have folders or a texting app, so here's Ice Cream Sandwich versus Gingerbread.
|
||||
Photo by Ron Amadeo
|
||||
|
||||
Folders were now much easier to make. In Gingerbread, you had to long press on the screen, pick "folders," and then pick "new folder." In Ice Cream Sandwich, just drag one icon on top of another, and a folder is created containing those two icons. It was dead simple and much easier than finding the hidden long-press command.
|
||||
|
||||
The design was much improved, too. Gingerbread used a generic beige folder icon, but Ice Cream Sandwich actually showed you what was in the folder by stacking the first three icons on top of each other, drawing a circle around them, and using that as the folder icon. Open folder containers resized to fit the amount of icons in the folder rather than being a full-screen, mostly empty box. It looked way, way better.
|
||||
|
||||
|
||||
YouTube switched to a more modern white theme and used a list view instead of the crazy 3D scrolling
|
||||
Photo by Ron Amadeo
|
||||
|
||||
YouTube was completely redesigned and looked less like something from The Matrix and more like, well, YouTube. It was a simple white list of vertically scrolling videos, just like the website. Making videos on your phone was given prime real estate, with the first button on the action bar dedicated to recording a video. Strangely, different screens used different YouTube logos in the top left, switching between a horizontal YouTube logo and a square one.
|
||||
|
||||
YouTube used swipe tabs just about everywhere. They were placed on the main page to browse and view your account and on the video pages to switch between comments, info, and related videos. The 4.0 app showed the first signs of Google+ YouTube integration, placing a "+1" icon next to the traditional rating buttons. Eventually Google+ would completely take over YouTube, turning the comments and author pages into Google+ activity.
|
||||
|
||||
|
||||
Ice Cream Sandwich tried to make things easier on everyone. Here is a screen for tracking data usage, the new developer options with tons of analytics enabled, and the intro tutorial.
|
||||
Photo by Ron Amadeo
|
||||
|
||||
Data Usage allowed users to easily keep track of and control their data usage. The main page showed a graph of this month's data usage, and users could set thresholds to be warned about data consumption or even set a hard usage limit to avoid overage charges. All of this was done easily by dragging the horizontal orange and red threshold lines higher or lower on the chart. The vertical white bars allowed users to select a slice of time in the graph. At the bottom of the page, the data usage for the selected time was broken down by app, so users could select a spike and easily see what app was sucking up all their data. When times got really tough, in the overflow button was an option to restrict all background data. Then, only apps running in the foreground could have access to the Internet connection.
|
||||
|
||||
The Developer Options typically only housed a tiny handful of settings, but in Ice Cream Sandwich the section received a huge expansion. Google added all sorts of on-screen diagnostic overlays to help app developers understand what was happening inside their app. You could view CPU usage, pointer location, and view screen updates. There were also options to change the way the system functioned, like control over animation speed, background processing, and GPU rendering.
|
||||
|
||||
One of the biggest differences between Android and the iOS is Android's app drawer interface. In Ice Cream Sandwich's quest to be more user-friendly, the initial startup launched a small tutorial showing users where the app drawer was and how to drag icons out of the drawer and onto the homescreen. With the removal of the off-screen menu button and changes like this, Android 4.0 made a big push to be more inviting to new smartphone users and switchers.
|
||||
|
||||
|
||||
The "touch to beam" NFC support, Google Earth, and App Info, which would let you disable crapware.
|
||||
|
||||
Built into Ice Cream Sandwich was full support for [NFC][1]. While previous devices like the Nexus S had NFC, support was limited and the OS couldn't do much with the chip. 4.0 added a feature called Android Beam, which would let two NFC-equipped Android 4.0 devices transfer data back and forth. NFC would transmit data related to whatever was on the screen at the time, so tapping when a phone displayed a webpage would send that page to the other phone. You could also send contact information, directions, and YouTube links. When the two phones were put together, the screen zoomed out, and tapping on the zoomed-out display would send the information.
|
||||
|
||||
In Android, users are not allowed to uninstall system apps, which are often integral to the function of the device. Carriers and OEMs took advantage of this and started putting crapware in the system partition, which they would often stick with software they didn't want. Android 4.0 allowed users to disable any app that couldn't be uninstalled, meaning the app remained on the system but didn't show up in the app drawer and couldn't be run. If users were willing to dig through the settings, this gave them an easy way to take control of their phone.
|
||||
|
||||
Android 4.0 can be thought of as the start of the modern Android era. Most of the Google apps released around this time only worked on Android 4.0 and above. There were so many new APIs that Google wanted to take advantage of that—initially at least—support for versions below 4.0 was limited. After Ice Cream Sandwich and Honeycomb, Google was really starting to get serious about software design. In January 2012, the company [finally launched][2] *Android Design*, a design guideline site that taught Android app developers how to create apps to match the look and feel of Android. This was something iOS not only had from the start of third-party app support, but Apple enforced design so seriously that apps that did not meet the guidelines were blocked from the App Store. The fact that Android went three years without any kind of public design documents from Google shows just how bad things used to be. But with Duarte in charge of Android's design revolution, the company was finally addressing basic design needs.
|
||||
|
||||
----------
|
||||
|
||||
|
||||
|
||||
[Ron Amadeo][a] / Ron is the Reviews Editor at Ars Technica, where he specializes in Android OS and Google products. He is always on the hunt for a new gadget and loves to rip things apart to see how they work.
|
||||
|
||||
[@RonAmadeo][t]
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: http://arstechnica.com/gadgets/2014/06/building-android-a-40000-word-history-of-googles-mobile-os/20/
|
||||
|
||||
译者：[译者ID](https://github.com/译者ID) 校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
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://arstechnica.com/gadgets/2011/02/near-field-communications-a-technology-primer/
|
||||
[2]:http://arstechnica.com/business/2012/01/google-launches-style-guide-for-android-developers/
|
||||
[a]:http://arstechnica.com/author/ronamadeo
|
||||
[t]:https://twitter.com/RonAmadeo
|
||||
@ -1,3 +1,5 @@
|
||||
alim0x translating
|
||||
|
||||
The history of Android
|
||||
================================================================================
|
||||
|
||||
@ -100,4 +102,4 @@ via: http://arstechnica.com/gadgets/2014/06/building-android-a-40000-word-histor
|
||||
[2]:http://arstechnica.com/gadgets/2012/07/divine-intervention-googles-nexus-7-is-a-fantastic-200-tablet/
|
||||
[3]:http://arstechnica.com/gadgets/2013/09/balky-carriers-and-slow-oems-step-aside-google-is-defragging-android/
|
||||
[a]:http://arstechnica.com/author/ronamadeo
|
||||
[t]:https://twitter.com/RonAmadeo
|
||||
[t]:https://twitter.com/RonAmadeo
|
||||
|
||||
@ -1,42 +0,0 @@
|
||||
Translating by DongShuaike
|
||||
|
||||
Backup (System Restore Point) your Ubuntu/Linux Mint with SystemBack
|
||||
================================================================================
|
||||
System Restore is must have feature for any OS that allows the user to revert their computer's state (including system files, installed applications, and system settings) to that of a previous point in time, which can be used to recover from system malfunctions or other problems.
|
||||
Sometimes installing a program or driver can make your OS go to blank screen. System Restore can return your PC's system files and programs to a time when everything was working fine, potentially preventing hours of troubleshooting headaches. It won't affect your documents, pictures, or other data.
|
||||
Simple system backup and restore application with extra features. [Systemback][1] makes it easy to create backups of system and users configuration files. In case of problems you can easily restore the previous state of the system. There are extra features like system copying, system installation and Live system creation.
|
||||
|
||||
Screenshots
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
**Note**: Using System Restore will not restore documents, music, emails, or personal files of any kind. Depending on your perspective, this is both a positive and negative feature. The bad news is that it won't restore that accidentally deleted file you wish you could get back, though a file recovery program might solve that problem.
|
||||
If no restore point exists on your computer, System Restore has nothing to revert to so the tool won't work for you. If you're trying to recover from a major problem, you'll need to move on to another troubleshooting step.
|
||||
|
||||
>>> Available for Ubuntu 15.10 Wily/16.04/15.04 Vivid/14.04 Trusty/Linux Mint 17.x/other Ubuntu derivatives
|
||||
To install SystemBack Application in Ubuntu/Linux Mint open Terminal (Press Ctrl+Alt+T) and copy the following commands in the Terminal:
|
||||
|
||||
Terminal Commands:
|
||||
|
||||
sudo add-apt-repository ppa:nemh/systemback
|
||||
sudo apt-get update
|
||||
sudo apt-get install systemback
|
||||
|
||||
That's it
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: http://www.noobslab.com/2015/11/backup-system-restore-point-your.html
|
||||
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[1]:https://launchpad.net/systemback
|
||||
@ -0,0 +1,83 @@
|
||||
Linux / Unix Desktop Fun: Christmas Tree For Your Terminal
|
||||
================================================================================
|
||||
Let us create Linux or Unix console Christmas tree just for fun and profit. First, you need to install a Perl module called Acme::POE::Tree. It is an animated Christmas tree module. I've tested this on Linux, OS X and Unix-like system.
|
||||
|
||||
### Install Acme::POE::Tree ###
|
||||
|
||||
The easiest way to install any perl module is to use the cpan (Comprehensive Perl Archive Network). Open the terminal application and type the following command to install Acme::POE::Tree:
|
||||
|
||||
## run as root ##
|
||||
perl -MCPAN -e 'install Acme::POE::Tree'
|
||||
|
||||
**Sample outputs:**
|
||||
|
||||
Installing /home/vivek/perl5/man/man3/POE::NFA.3pm
|
||||
Installing /home/vivek/perl5/man/man3/POE::Kernel.3pm
|
||||
Installing /home/vivek/perl5/man/man3/POE::Loop.3pm
|
||||
Installing /home/vivek/perl5/man/man3/POE::Resource.3pm
|
||||
Installing /home/vivek/perl5/man/man3/POE::Filter::Map.3pm
|
||||
Installing /home/vivek/perl5/man/man3/POE::Resource::SIDs.3pm
|
||||
Installing /home/vivek/perl5/man/man3/POE::Loop::IO_Poll.3pm
|
||||
Installing /home/vivek/perl5/man/man3/POE::Pipe::TwoWay.3pm
|
||||
Appending installation info to /home/vivek/perl5/lib/perl5/x86_64-linux-gnu-thread-multi/perllocal.pod
|
||||
RCAPUTO/POE-1.367.tar.gz
|
||||
/usr/bin/make install -- OK
|
||||
RCAPUTO/Acme-POE-Tree-1.022.tar.gz
|
||||
Has already been unwrapped into directory /home/vivek/.cpan/build/Acme-POE-Tree-1.022-uhlZUz
|
||||
RCAPUTO/Acme-POE-Tree-1.022.tar.gz
|
||||
Has already been prepared
|
||||
Running make for R/RC/RCAPUTO/Acme-POE-Tree-1.022.tar.gz
|
||||
cp lib/Acme/POE/Tree.pm blib/lib/Acme/POE/Tree.pm
|
||||
Manifying 1 pod document
|
||||
RCAPUTO/Acme-POE-Tree-1.022.tar.gz
|
||||
/usr/bin/make -- OK
|
||||
Running make test
|
||||
PERL_DL_NONLAZY=1 "/usr/bin/perl" "-MExtUtils::Command::MM" "-MTest::Harness" "-e" "undef *Test::Harness::Switches; test_harness(0, 'blib/lib', 'blib/arch')" t/*.t
|
||||
t/01_basic.t .. ok
|
||||
All tests successful.
|
||||
Files=1, Tests=2, 6 wallclock secs ( 0.09 usr 0.03 sys + 0.53 cusr 0.06 csys = 0.71 CPU)
|
||||
Result: PASS
|
||||
RCAPUTO/Acme-POE-Tree-1.022.tar.gz
|
||||
Tests succeeded but one dependency not OK (Curses)
|
||||
RCAPUTO/Acme-POE-Tree-1.022.tar.gz
|
||||
[dependencies] -- NA
|
||||
|
||||
### Show Christmas tree in the shell ###
|
||||
|
||||
Simply type the following command:
|
||||
|
||||
perl -MAcme::POE::Tree -e 'Acme::POE::Tree->new()->run()'
|
||||
|
||||
**Sample outputs:**
|
||||
|
||||
|
||||
|
||||
Gif 01: An animated christmas tree in Perl
|
||||
|
||||
### Tree customization ###
|
||||
|
||||
Here is my tree.pl:
|
||||
|
||||
#!/usr/bin/perl
|
||||
|
||||
use Acme::POE::Tree;
|
||||
my $tree = Acme::POE::Tree->new(
|
||||
{
|
||||
star_delay => 1.5, # shimmer star every 1.5 sec
|
||||
light_delay => 2, # twinkle lights every 2 sec
|
||||
run_for => 10, # automatically exit after 10 sec
|
||||
}
|
||||
);
|
||||
$tree->run();
|
||||
|
||||
Now can play with your tree modifying star_delay, run_for, and light_delay. And ,there you have it a a Christmas tree in your shell for fun.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: http://www.cyberciti.biz/open-source/command-line-hacks/linux-unix-desktop-fun-christmas-tree-for-your-terminal/
|
||||
|
||||
作者：Vivek Gite
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
@ -1,16 +1,17 @@
|
||||
bazz2
|
||||
Learn with Linux: Learning Music
|
||||
================================================================================
|
||||
|
||||
|
||||
This article is part of the [Learn with Linux][1] series:
|
||||
[Linux 学习系列][1]的所有文章：
|
||||
|
||||
- [Learn with Linux: Learning to Type][2]
|
||||
- [Learn with Linux: Physics Simulation][3]
|
||||
- [Learn with Linux: Learning Music][4]
|
||||
- [Learn with Linux: Two Geography Apps][5]
|
||||
- [Learn with Linux: Master Your Math with These Linux Apps][6]
|
||||
- [Linux 教学之教你练打字][2]
|
||||
- [Linux 教学之物理模拟][3]
|
||||
- [Linux 教学之教你玩音乐][4]
|
||||
- [Linux 教学之两款地理软件][5]
|
||||
- [Linux 教学之掌握数学][6]
|
||||
|
||||
Linux offers great educational software and many excellent tools to aid students of all grades and ages in learning and practicing a variety of topics, often interactively. The “Learn with Linux” series of articles offers an introduction to a variety of educational apps and software.
|
||||
引言：Linux 提供大量的教学软件和工具，面向各个年级段以及年龄段，提供大量学科的练习实践，其中大多数是可以与用户进行交互的。本“Linux 教学”系列就来介绍一些教学软件。
|
||||
|
||||
Learning music is a great pastime. Training your ears to identify scales and chords and mastering an instrument or your own voice requires lots of practise and could become difficult. Music theory is extensive. There is much to memorize, and to turn it into a “skill” you will need diligence. Linux offers exceptional software to help you along your musical journey. They will not help you become a professional musician instantly but could ease the process of learning, being a great aide and reference point.
|
||||
|
||||
@ -152,4 +153,4 @@ via: https://www.maketecheasier.com/linux-learning-music/
|
||||
[10]:http://sourceforge.net/projects/tete/files/latest/download
|
||||
[11]:http://sourceforge.net/projects/jalmus/files/Jalmus-2.3/
|
||||
[12]:http://tuxguitar.herac.com.ar/
|
||||
[13]:http://www.linuxlinks.com/article/20090517041840856/PianoBooster.html
|
||||
[13]:http://www.linuxlinks.com/article/20090517041840856/PianoBooster.html
|
||||
|
||||
@ -1,108 +0,0 @@
|
||||
[bazz222222]
|
||||
Linux 学习系列之物理模拟
|
||||
================================================================================
|
||||
|
||||
|
||||
[Linux 学习系列][1]的所有文章：
|
||||
|
||||
- [Learn with Linux: Learning to Type][2]
|
||||
- [Learn with Linux: Physics Simulation][3]
|
||||
- [Learn with Linux: Learning Music][4]
|
||||
- [Learn with Linux: Two Geography Apps][5]
|
||||
- [Learn with Linux: Master Your Math with These Linux Apps][6]
|
||||
|
||||
Linux offers great educational software and many excellent tools to aid students of all grades and ages in learning and practicing a variety of topics, often interactively. The “Learn with Linux” series of articles offers an introduction to a variety of educational apps and software.
|
||||
|
||||
Physics is an interesting subject, and arguably the most enjoyable part of any Physics class/lecture are the demonstrations. It is really nice to see physics in action, yet the experiments do not need to be restricted to the classroom. While Linux offers many great tools for scientists to support or conduct experiments, this article will concern a few that would make learning physics easier or more fun.
|
||||
|
||||
### 1. Step ###
|
||||
|
||||
[Step][7] is an interactive physics simulator, part of [KDEEdu, the KDE Education Project][8]. Nobody could better describe what Step does than the people who made it. According to the project webpage, “[Step] works like this: you place some bodies on the scene, add some forces such as gravity or springs, then click “Simulate” and Step shows you how your scene will evolve according to the laws of physics. You can change every property of bodies/forces in your experiment (even during simulation) and see how this will change the outcome of the experiment. With Step, you can not only learn but feel how physics works!”
|
||||
|
||||
While of course it requires Qt and loads of KDE-specific dependencies to work, projects like this (and KDEEdu itself) are part of the reason why KDE is such an awesome environment (if you don’t mind running a heavier desktop, of course).
|
||||
|
||||
Step is in the Debian repositories; to install it on derivatives, simply type
|
||||
|
||||
sudo apt-get install step
|
||||
|
||||
into a terminal. On a KDE system it should have minimal dependencies and install in seconds.
|
||||
|
||||
Step has a simple interface, and it lets you jump right into simulations.
|
||||
|
||||
|
||||
|
||||
You will find all available objects on the left-hand side. You can have different particles, gas, shaped objects, springs, and different forces in action. (1) If you select an object, a short description of it will appear on the right-hand side (2). On the right you will also see an overview of the “world” you have created (the objects it contains) (3), the properties of the currently selected object (4), and the steps you have taken so far (5).
|
||||
|
||||
|
||||
|
||||
Once you have placed all you wanted on the canvas, just press “Simulate,” and watch the events unfold as the objects interact with each other.
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
To get to know Step better you only need to press F1. The KDE Help Center offers a great and detailed Step handbook.
|
||||
|
||||
### 2. Lightspeed ###
|
||||
|
||||
Lightspeed is a simple GTK+ and OpenGL based simulator that is meant to demonstrate the effect of how one might observe a fast moving object. Lightspeed will simulate these effects based on Einstein’s special relativity. According to [their sourceforge page][9] “When an object accelerates to more than a few million meters per second, it begins to appear warped and discolored in strange and unusual ways, and as it approaches the speed of light (299,792,458 m/s) the effects become more and more bizarre. In addition, the manner in which the object is distorted varies drastically with the viewpoint from which it is observed.”
|
||||
|
||||
These effects which come into play at relative velocities are:
|
||||
|
||||
- **The Lorentz contraction** – causes the object to appear shorter
|
||||
- **The Doppler red/blue shift** – alters the hues of color observed
|
||||
- **The headlight effect** – brightens or darkens the object
|
||||
- **Optical aberration** – deforms the object in unusual ways
|
||||
|
||||
Lightspeed is in the Debian repositories; to install it, simply type:
|
||||
|
||||
sudo apt-get install lightspeed
|
||||
|
||||
The user interface is very simple. You get a shape (more can be downloaded from sourceforge) which would move along the x-axis (animation can be started by processing “A” or by selecting it from the object menu).
|
||||
|
||||
|
||||
|
||||
You control the speed of its movement with the right-hand side slider and watch how it deforms.
|
||||
|
||||
|
||||
|
||||
Some simple controls will allow you to add more visual elements
|
||||
|
||||
|
||||
|
||||
The viewing angles can be adjusted by pressing either the left, middle or right button and dragging the mouse or from the Camera menu that also offers some other adjustments like background colour or graphics mode.
|
||||
|
||||
### Notable mention: Physion ###
|
||||
|
||||
Physion looks like an interesting project and a great looking software to simulate physics in a much more colorful and fun way than the above examples would allow. Unfortunately, at the time of writing, the [official website][10] was experiencing problems, and the download page was unavailable.
|
||||
|
||||
Judging from their Youtube videos, Physion must be worth installing once a download line becomes available. Until then we can just enjoy the this video demo.
|
||||
|
||||
注：youtube 视频
|
||||
<iframe frameborder="0" src="//www.youtube.com/embed/P32UHa-3BfU?autoplay=1&autohide=2&border=0&wmode=opaque&enablejsapi=1&controls=0&showinfo=0" id="youtube-iframe"></iframe>
|
||||
|
||||
Do you have another favorite physics simulation/demonstration/learning applications for Linux? Please share with us in the comments below.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.maketecheasier.com/linux-physics-simulation/
|
||||
|
||||
作者：[Attila Orosz][a]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://www.maketecheasier.com/author/attilaorosz/
|
||||
[1]:https://www.maketecheasier.com/series/learn-with-linux/
|
||||
[2]:https://www.maketecheasier.com/learn-to-type-in-linux/
|
||||
[3]:https://www.maketecheasier.com/linux-physics-simulation/
|
||||
[4]:https://www.maketecheasier.com/linux-learning-music/
|
||||
[5]:https://www.maketecheasier.com/linux-geography-apps/
|
||||
[6]:https://www.maketecheasier.com/learn-linux-maths/
|
||||
[7]:https://edu.kde.org/applications/all/step
|
||||
[8]:https://edu.kde.org/
|
||||
[9]:http://lightspeed.sourceforge.net/
|
||||
[10]:http://www.physion.net/
|
||||
@ -0,0 +1,43 @@
|
||||
|
||||
苹果编程语言Swift开始支持Linux
|
||||
================================================================================
|
||||
|
||||
|
||||
苹果也开源了？是的，苹果编程语言Swift已经开源了。其实我们并不应该感到意外，因为[在六个月以前苹果就已经宣布了这个消息][1]。
|
||||
|
||||
苹果宣布这周将推出开源Swift社区。一个专用于开源Swift社区的[新网站][2]已经就位，网站首页显示以下信息：
|
||||
|
||||
> 我们对Swift开源感到兴奋。在苹果推出了编程语言Swift之后，它很快成为历史上增长最快的语言之一。Swift可以编写出难以置信的又快又安全的软件。目前，Swift是开源的，你能帮助做出随处可用的最好的通用编程语言。
|
||||
|
||||
[swift.org][2]这个网站将会作为一站式网站，它会提供各种资料的下载，包括各种平台，社区指南，最新消息，入门教程，贡献开源Swift的说明，文件和一些其他的指南。 如果你正期待着学习Swift，那么必须收藏这个网站。
|
||||
|
||||
在苹果的这次宣布中，一个用于方便分享和构建代码的包管理器已经可用了。
|
||||
|
||||
对于所有的Linux使用者来说，最重要的是，源代码已经可以从[Github][3]获得了.你可以从以下链接Checkout它：
|
||||
Most important of all for Linux users, the source code is now available at [Github][3]. You can check it out from the link below:
|
||||
|
||||
- [苹果Swift源代码][3]
|
||||
|
||||
除此之外，对于ubuntu 14.04和15.10版本还有预编译的二进制文件。
|
||||
|
||||
- [ubuntu系统的Swift二进制文件][4]
|
||||
|
||||
不要急着去使用它们，因为这些都是发展分支而且不适合于专用机器。因此现在避免使用，一旦发布了Linux下Swift的稳定版本，我希望ubuntu会把它包含在[umake][5]中靠近[Visual Studio][6]的地方。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: http://itsfoss.com/swift-open-source-linux/
|
||||
|
||||
作者：[Abhishek][a]
|
||||
译者：[Flowsnow](https://github.com/Flowsnow)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:http://itsfoss.com/author/abhishek/
|
||||
[1]:http://itsfoss.com/apple-open-sources-swift-programming-language-linux/
|
||||
[2]:https://swift.org/
|
||||
[3]:https://github.com/apple
|
||||
[4]:https://swift.org/download/#latest-development-snapshots
|
||||
[5]:https://wiki.ubuntu.com/ubuntu-make
|
||||
[6]:http://itsfoss.com/install-visual-studio-code-ubuntu/
|
||||
@ -0,0 +1,69 @@
|
||||
黑客利用Wi-Fi侵犯你隐私的七种方法
|
||||
================================================================================
|
||||
|
||||
|
||||
### 黑客利用Wi-Fi侵犯你隐私的七种方法 ###
|
||||
|
||||
Wi-Fi — 既然方便又危险的东西！这里给大家介绍一下通过Wi-Fi连接泄露身份信息的七种方法和预防措施。
|
||||
|
||||
|
||||
|
||||
### 利用免费热点 ###
|
||||
|
||||
它们似乎无处不在，而且它们的数量会在[下一个四年里增加四倍][1]。但是它们当中很多都是不值得信任的，从你的登录凭证、email甚至更加敏感的账户，都能被黑客用一款名叫“sniffers”的软件截获 — 这款软件能截获到任何你通过该连接提交的信息。防止被黑客盯上的最好办法就是使用VPN(virtual private network)，它能保护你的数据隐私它会加密你所输入的信息。
|
||||
|
||||
|
||||
|
||||
### 网上银行 ###
|
||||
|
||||
你可能认为没有人需要自己被提醒不要使用免费Wi-Fi来操作网上银行, 但网络安全厂商卡巴斯基实验室表示[全球超过100家银行因为网络黑客而损失9亿美元][2]，由此可见还是有很多人因此受害。如果你真的想要在一家咖吧里使用免费真实的Wi-Fi，那么你应该向服务员确认网络名称。[在店里用路由器设置一个开放的无线连接][3]并将它的网络名称设置成店名是一件相当简单的事。
|
||||
|
||||
|
||||
|
||||
### 始终开着Wi-Fi开关 ###
|
||||
|
||||
如果你手机的Wi-Fi开关一直开着的，你会自动被连接到一个不安全的网络中去，你甚至都没有意识到。你可以利用你手机的[基于位置的Wi-Fi功能][4]，如果它是可用的，那它会在你离开你所保存的网络范围后自动关闭你的Wi-Fi开关并在你回去之后再次开启。
|
||||
|
||||
|
||||
|
||||
### 不使用防火墙 ###
|
||||
|
||||
防火墙是你的第一道抵御恶意入侵的防线，它能有效地让你的电脑网络通畅并阻挡黑客和恶意软件。你应该时刻开启它除非你的杀毒软件有它自己的防火墙。
|
||||
|
||||
|
||||
|
||||
### 浏览非加密网页 ###
|
||||
|
||||
说起来很难过，[世界上排名前100万个网站中55%是不加密的][5]，一个未加密的网站则会让传输的数据暴露在黑客的眼下。如果一个网页是安全的，你的浏览器则会有标明(比如说火狐浏览器是一把绿色的挂锁、Chrome蓝旗则是个绿色的图标)。但是一个安全的网站不能让你免于被劫持的风险，它能通过公共网络从你访问过的网站上窃取cookies，无论是不是正当网站与否。
|
||||
|
||||
|
||||
|
||||
### 不更新你的安全防护软件 ###
|
||||
|
||||
如果你想要确保你自己的网络是受保护的，就更新的路由器固件。你要做的就是进入你的路由器管理页面去检查，通常你能在厂商的官方网页上下载到最新的固件版本。
|
||||
|
||||
|
||||
|
||||
### 不保护你的家用Wi-Fi ###
|
||||
|
||||
不用说，设置一个复杂的密码和更改无线连接的默认名都是非常重要的。你还可以过滤你的MAC地址来让你的路由器只承认那些确认过的设备。
|
||||
|
||||
**Josh Althuser**是一个开源支持者、网络架构师和科技企业家。在过去12年里，他花了很多时间去倡导使用开源软件来管理团队和项目，同时为网络应用程序提供企业级咨询并帮助它们走向市场。你可以联系[他的推特][6].
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: http://www.networkworld.com/article/3003170/mobile-security/7-ways-hackers-can-use-wi-fi-against-you.html
|
||||
|
||||
作者：[Josh Althuser][a]
|
||||
译者：[ZTinoZ](https://github.com/ZTinoZ)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://twitter.com/JoshAlthuser
|
||||
[1]:http://www.pcworld.com/article/243464/number_of_wifi_hotspots_to_quadruple_by_2015_says_study.html
|
||||
[2]:http://www.nytimes.com/2015/02/15/world/bank-hackers-steal-millions-via-malware.html?hp&action=click&pgtype=Homepage&module=first-column-region%C2%AEion=top-news&WT.nav=top-news&_r=3
|
||||
[3]:http://news.yahoo.com/blogs/upgrade-your-life/banking-online-not-hacked-182159934.html
|
||||
[4]:http://pocketnow.com/2014/10/15/should-you-leave-your-smartphones-wifi-on-or-turn-it-off
|
||||
[5]:http://www.cnet.com/news/chrome-becoming-tool-in-googles-push-for-encrypted-web/
|
||||
[6]:https://twitter.com/JoshAlthuser
|
||||
@ -0,0 +1,299 @@
|
||||
点评：Linux编程中五款内存调试器
|
||||
================================================================================
|
||||
|
||||
Credit: [Moini][1]
|
||||
|
||||
作为一个程序员，我知道我总在犯错误——事实是，怎么可能会不犯错的！程序员也是人啊。有的错误能在编码过程中及时发现，而有些却得等到软件测试才显露出来。然而，有一类错误并不能在这两个时期被排除，从而导致软件不能正常运行，甚至是提前中止。
|
||||
|
||||
想到了吗？我说的就是内存相关的错误。手动调试这些错误不仅耗时，而且很难发现并纠正。值得一提的是，这种错误非常地常见，特别是在一些软件里，这些软件是用C/C++这类允许[手动管理内存][2]的语言编写的。
|
||||
|
||||
幸运的是，现行有一些编程工具能够帮你找到软件程序中这些内存相关的错误。在这些工具集中，我评定了五款Linux可用的，流行、免费并且开源的内存调试器：Dmalloc、Electric Fence、 Memcheck、 Memwatch以及Mtrace。日常编码过程中我已经把这五个调试器用了个遍，所以这些点评是建立在我的实际体验之上的。
|
||||
|
||||
### [Dmalloc][3] ###
|
||||
|
||||
**开发者**：Gray Watson
|
||||
|
||||
**点评版本**：5.5.2
|
||||
|
||||
**Linux支持**：所有种类
|
||||
|
||||
**许可**：知识共享署名-相同方式共享许可证3.0
|
||||
|
||||
Dmalloc是Gray Watson开发的一款内存调试工具。它实现成库，封装了标准内存管理函数如**malloc(), calloc(), free()**等，使得程序员得以检测出有问题的代码。
|
||||
|
||||
|
||||
Dmalloc
|
||||
|
||||
如同工具的网页所列，这个调试器提供的特性包括内存泄漏跟踪、[重复释放(double free)][4]错误跟踪、以及[越界写入(fence-post write)][5]检测。其它特性包括文件/行号报告、普通统计记录。
|
||||
|
||||
#### 更新内容 ####
|
||||
|
||||
5.5.2版本是一个[bug修复发行版][6]，同时修复了构建和安装的问题。
|
||||
|
||||
#### 有何优点 ####
|
||||
|
||||
Dmalloc最大的优点是可以进行任意配置。比如说，你可以配置以支持C++程序和多线程应用。Dmalloc还提供一个有用的功能：运行时可配置，这表示在Dmalloc执行时，可以轻易地使能或者禁能它提供的特性。
|
||||
|
||||
你还可以配合[GNU Project Debugger (GDB)][7]来使用Dmalloc，只需要将dmalloc.gdb文件（位于Dmalloc源码包中的contrib子目录里）的内容添加到你的主目录中的.gdbinit文件里即可。
|
||||
|
||||
另外一个优点让我对Dmalloc爱不释手的是它有大量的资料文献。前往官网的[Documentation标签][8]，可以获取任何内容，有关于如何下载、安装、运行，怎样使用库，和Dmalloc所提供特性的细节描述，及其输入文件的解释。里面还有一个章节介绍了一般问题的解决方法。
|
||||
|
||||
#### 注意事项 ####
|
||||
|
||||
跟Mtrace一样，Dmalloc需要程序员改动他们的源代码。比如说你可以（必须的）添加头文件**dmalloc.h**，工具就能汇报产生问题的调用的文件或行号。这个功能非常有用，因为它节省了调试的时间。
|
||||
|
||||
除此之外，还需要在编译你的程序时，把Dmalloc库（编译源码包时产生的）链接进去。
|
||||
|
||||
然而，还有点更麻烦的事，需要设置一个环境变量，命名为**DMALLOC_OPTION**，以供工具在运行时配置内存调试特性，以及输出文件的路径。可以手动为该环境变量分配一个值，不过初学者可能会觉得这个过程有点困难，因为你想使能的Dmalloc特性是存在于这个值之中的——表示为各自的十六进制值的累加。[这里][9]有详细介绍。
|
||||
|
||||
一个比较简单方法设置这个环境变量是使用[Dmalloc实用指令][10]，这是专为这个目的设计的方法。
|
||||
|
||||
#### 总结 ####
|
||||
|
||||
Dmalloc真正的优势在于它的可配置选项。而且高度可移植，曾经成功移植到多种操作系统如AIX、BSD/OS、DG/UX、Free/Net/OpenBSD、GNU/Hurd、HPUX、Irix、Linux、MS-DOG、NeXT、OSF、SCO、Solaris、SunOS、Ultrix、Unixware甚至Unicos（运行在Cray T3E主机上）。虽然Dmalloc有很多东西需要学习，但是它所提供的特性值得为之付出。
|
||||
|
||||
### [Electric Fence][15] ###
|
||||
|
||||
**开发者**：Bruce Perens
|
||||
|
||||
**点评版本**：2.2.3
|
||||
|
||||
**Linux支持**：所有种类
|
||||
|
||||
**许可**：GNU 通用公共许可证 (第二版)
|
||||
|
||||
Electric Fence是Bruce Perens开发的一款内存调试工具，它以库的形式实现，你的程序需要链接它。Electric Fence能检测出[栈][11]内存溢出和访问已经释放的内存。
|
||||
|
||||
|
||||
Electric Fence
|
||||
|
||||
顾名思义，Electric Fence在每个申请的缓存边界建立了fence（防护），任何非法内存访问都会导致[段错误][12]。这个调试工具同时支持C和C++编程。
|
||||
|
||||
|
||||
#### 更新内容 ####
|
||||
|
||||
2.2.3版本修复了工具的构建系统，使得-fno-builtin-malloc选项能真正传给[GNU Compiler Collection (GCC)][13]。
|
||||
|
||||
#### 有何优点 ####
|
||||
|
||||
我喜欢Electric Fence首要的一点是（Memwatch、Dmalloc和Mtrace所不具有的），这个调试工具不需要你的源码做任何的改动，你只需要在编译的时候把它的库链接进你的程序即可。
|
||||
|
||||
其次，Electric Fence实现一个方法，确认导致越界访问(a bounds violation)的第一个指令就是引起段错误的原因。这比在后面再发现问题要好多了。
|
||||
|
||||
不管是否有检测出错误，Electric Fence经常会在输出产生版权信息。这一点非常有用，由此可以确定你所运行的程序已经启用了Electric Fence。
|
||||
|
||||
#### 注意事项 ####
|
||||
|
||||
另一方面，我对Electric Fence真正念念不忘的是它检测内存泄漏的能力。内存泄漏是C/C++软件最常见也是最难隐秘的问题之一。不过，Electric Fence不能检测出堆内存溢出，而且也不是线程安全的。
|
||||
|
||||
基于Electric Fence会在用户分配内存区的前后分配禁止访问的虚拟内存页，如果你过多的进行动态内存分配，将会导致你的程序消耗大量的额外内存。
|
||||
|
||||
Electric Fence还有一个局限是不能明确指出错误代码所在的行号。它所能做只是在监测到内存相关错误时产生段错误。想要定位行号，需要借助[The Gnu Project Debugger (GDB)][14]这样的调试工具来调试你启用了Electric Fence的程序。
|
||||
|
||||
最后一点，Electric Fence虽然能检测出大部分的缓冲区溢出，有一个例外是，如果所申请的缓冲区大小不是系统字长的倍数，这时候溢出（即使只有几个字节）就不能被检测出来。
|
||||
|
||||
#### 总结 ####
|
||||
|
||||
尽管有那么多的局限，但是Electric Fence的优点却在于它的易用性。程序只要链接工具一次，Electric Fence就可以在监测出内存相关问题的时候报警。不过，如同前面所说，Electric Fence需要配合像GDB这样的源码调试器使用。
|
||||
|
||||
|
||||
### [Memcheck][16] ###
|
||||
|
||||
**开发者**：[Valgrind开发团队][17]
|
||||
|
||||
**点评版本**：3.10.1
|
||||
|
||||
**Linux支持**：所有种类
|
||||
|
||||
**许可**：通用公共许可证
|
||||
|
||||
[Valgrind][18]是一个提供好几款调试和Linux程序性能分析工具的套件。虽然Valgrind和编写语言各不相同（有Java、Perl、Python、Assembly code、ortran、Ada等等）的程序配合工作，但是它所提供的工具大部分都意在支持C/C++所编写的程序。
|
||||
|
||||
Memcheck作为内存错误检测器，是一款最受欢迎的Memcheck工具。它能够检测出诸多问题诸如内存泄漏、无效的内存访问、未定义变量的使用以及栈内存分配和释放相关的问题等。
|
||||
|
||||
#### 更新内容 ####
|
||||
|
||||
工具套件(3.10.1)的[发行版][19]是一个副版本，主要修复了3.10.0版本发现的bug。除此之外，从主版本backport一些包，修复了缺失的AArch64 ARMv8指令和系统调用。
|
||||
|
||||
#### 有何优点 ####
|
||||
|
||||
同其它所有Valgrind工具一样，Memcheck也是基本的命令行实用程序。它的操作非常简单：通常我们会使用诸如prog arg1 arg2格式的命令来运行程序，而Memcheck只要求你多加几个值即可，就像valgrind --leak-check=full prog arg1 arg2。
|
||||
|
||||
|
||||
Memcheck
|
||||
|
||||
（注意：因为Memcheck是Valgrind的默认工具所以无需提及Memcheck。但是，需要在编译程序之初带上-g参数选项，这一步会添加调试信息，使得Memcheck的错误信息会包含正确的行号。）
|
||||
|
||||
我真正倾心于Memcheck的是它提供了很多命令行选项（如上所述的--leak-check选项），如此不仅能控制工具运转还可以控制它的输出。
|
||||
|
||||
举个例子，可以开启--track-origins选项，以查看程序源码中未初始化的数据。可以开启--show-mismatched-frees选项让Memcheck匹配内存的分配和释放技术。对于C语言所写的代码，Memcheck会确保只能使用free()函数来释放内存，malloc()函数来申请内存。而对C++所写的源码，Memcheck会检查是否使用了delete或delete[]操作符来释放内存，以及new或者new[]来申请内存。
|
||||
|
||||
Memcheck最好的特点，尤其是对于初学者来说的，是它会给用户建议使用那个命令行选项能让输出更加有意义。比如说，如果你不使用基本的--leak-check选项，Memcheck会在输出时建议“使用--leak-check=full重新运行，查看更多泄漏内存细节”。如果程序有未初始化的变量，Memcheck会产生信息“使用--track-origins=yes，查看未初始化变量的定位”。
|
||||
|
||||
Memcheck另外一个有用的特性是它可以[创建抑制文件(suppression files)][20]，由此可以忽略特定不能修正的错误，这样Memcheck运行时就不会每次都报警了。值得一提的是，Memcheck会去读取默认抑制文件来忽略系统库（比如C库）中的报错，这些错误在系统创建之前就已经存在了。可以选择创建一个新的抑制文件，或是编辑现有的(通常是/usr/lib/valgrind/default.supp)。
|
||||
|
||||
Memcheck还有高级功能，比如可以使用[定制内存分配器][22]来[检测内存错误][21]。除此之外，Memcheck提供[监控命令][23]，当用到Valgrind的内置gdbserver，以及[客户端请求][24]机制（不仅能把程序的行为告知Memcheck，还可以进行查询）时可以使用。
|
||||
|
||||
#### 注意事项 ####
|
||||
|
||||
毫无疑问，Memcheck可以节省很多调试时间以及省去很多麻烦。但是它使用了很多内存，导致程序执行变慢（[由资料可知][25]，大概花上20至30倍时间）。
|
||||
|
||||
除此之外，Memcheck还有其它局限。根据用户评论，Memcheck明显不是[线程安全][26]的；它不能检测出 [静态缓冲区溢出][27]；还有就是，一些Linux程序如[GNU Emacs][28]，目前还不能使用Memcheck。
|
||||
|
||||
如果有兴趣，可以在[这里][29]查看Valgrind详尽的局限性说明。
|
||||
|
||||
#### 总结 ####
|
||||
|
||||
无论是对于初学者还是那些需要高级特性的人来说，Memcheck都是一款便捷的内存调试工具。如果你仅需要基本调试和错误核查，Memcheck会非常容易上手。而当你想要使用像抑制文件或者监控指令这样的特性，就需要花一些功夫学习了。
|
||||
|
||||
虽然罗列了大量的局限性，但是Valgrind（包括Memcheck）在它的网站上声称全球有[成千上万程序员][30]使用了此工具。开发团队称收到来自超过30个国家的用户反馈，而这些用户的工程代码有的高达2.5千万行。
|
||||
|
||||
### [Memwatch][31] ###
|
||||
|
||||
**开发者**：Johan Lindh
|
||||
|
||||
**点评版本**：2.71
|
||||
|
||||
**Linux支持**：所有种类
|
||||
|
||||
**许可**：GNU通用公共许可证
|
||||
|
||||
Memwatch是由Johan Lindh开发的内存调试工具，虽然它主要扮演内存泄漏检测器的角色，但是它也具有检测其它如[重复释放跟踪和内存错误释放][32]、缓冲区溢出和下溢、[野指针][33]写入等等内存相关问题的能力（根据网页介绍所知）。
|
||||
|
||||
Memwatch支持用C语言所编写的程序。可以在C++程序中使用它，但是这种做法并不提倡（由Memwatch源码包随附的Q&A文件中可知）。
|
||||
|
||||
#### 更新内容 ####
|
||||
|
||||
这个版本添加了ULONG_LONG_MAX以区分32位和64位程序。
|
||||
|
||||
#### 有何优点 ####
|
||||
|
||||
跟Dmalloc一样，Memwatch也有优秀的文献资料。参考USING文件，可以学习如何使用Memwatch，可以了解Memwatch是如何初始化、如何清理以及如何进行I/O操作的，等等不一而足。还有一个FAQ文件，旨在帮助用户解决使用过程遇到的一般问题。最后还有一个test.c文件提供工作案例参考。
|
||||
|
||||
|
||||
Memwatch
|
||||
|
||||
不同于Mtrace，Memwatch的输出产生的日志文件（通常是memwatch.log）是人类可阅读格式。而且，Memwatch每次运行时总会拼接内存调试输出到此文件末尾，而不是进行覆盖（译改）。如此便可在需要之时，轻松查看之前的输出信息。
|
||||
|
||||
同样值得一提的是当你执行了启用Memwatch的程序，Memwatch会在[标准输出][34]中产生一个单行输出，告知发现了错误，然后你可以在日志文件中查看输出细节。如果没有产生错误信息，就可以确保日志文件不会写入任何错误，多次运行的话能实际节省时间。
|
||||
|
||||
另一个我喜欢的优点是Memwatch同样在源码中提供一个方法，你可以据此获取Memwatch的输出信息，然后任由你进行处理（参考Memwatch源码中的mwSetOutFunc()函数获取更多有关的信息）。
|
||||
|
||||
#### 注意事项 ####
|
||||
|
||||
跟Mtrace和Dmalloc一样，Memwatch也需要你往你的源文件里增加代码：你需要把memwatch.h这个头文件包含进你的代码。而且，编译程序的时候，你需要连同memwatch.c一块编译；或者你可以把已经编译好的目标模块包含起来，然后在命令行定义MEMWATCH和MW_STDIO变量。不用说，想要在输出中定位行号，-g编译器选项也少不了。
|
||||
|
||||
还有一些没有具备的特性。比如Memwatch不能检测出往一块已经被释放的内存写入操作，或是在分配的内存块之外的读取操作。而且，Memwatch也不是线程安全的。还有一点，正如我在开始时指出，在C++程序上运行Memwatch的结果是不能预料的。
|
||||
|
||||
#### 总结 ####
|
||||
|
||||
Memcheck可以检测很多内存相关的问题，在处理C程序时是非常便捷的调试工具。因为源码小巧，所以可以从中了解Memcheck如何运转，有需要的话可以调试它，甚至可以根据自身需求扩展升级它的功能。
|
||||
|
||||
### [Mtrace][35] ###
|
||||
|
||||
**开发者**: Roland McGrath and Ulrich Drepper
|
||||
|
||||
**点评版本**: 2.21
|
||||
|
||||
**Linux支持**：所有种类
|
||||
|
||||
**许可**：GNU通用公共许可证
|
||||
|
||||
Mtrace是[GNU C库][36]中的一款内存调试工具，同时支持Linux C和C++程序，检测由malloc()和free()函数的不对等调用所引起的内存泄漏问题。
|
||||
|
||||
|
||||
Mtrace
|
||||
|
||||
Mtrace实现为对mtrace()函数的调用，跟踪程序中所有malloc/free调用，在用户指定的文件中记录相关信息。文件以一种机器可读的格式记录数据，所以有一个Perl脚本（同样命名为mtrace）用来把文件转换并展示为人类可读格式。
|
||||
|
||||
#### 更新内容 ####
|
||||
|
||||
[Mtrace源码][37]和[Perl文件][38]同GNU C库(2.21版本)一起释出，除了更新版权日期，其它别无改动。
|
||||
|
||||
#### 有何优点 ####
|
||||
|
||||
Mtrace最优秀的特点是非常简单易学。你只需要了解在你的源码中如何以及何处添加mtrace()及其对立的muntrace()函数，还有如何使用Mtrace的Perl脚本。后者非常简单，只需要运行指令mtrace <program-executable> <log-file-generated-upon-program-execution>（例子见开头截图最后一条指令）。
|
||||
|
||||
Mtrace另外一个优点是它的可收缩性，体现在，不仅可以使用它来调试完整的程序，还可以使用它来检测程序中独立模块的内存泄漏。只需在每个模块里调用mtrace()和muntrace()即可。
|
||||
|
||||
最后一点，因为Mtrace会在mtace()（在源码中添加的函数）执行时被触发，因此可以很灵活地[使用信号][39]动态地（在程序执行周期内）使能Mtrace。
|
||||
|
||||
#### 注意事项 ####
|
||||
|
||||
因为mtrace()和mauntrace()函数（在mcheck.h文件中声明，所以必须在源码中包含此头文件）的调用是Mtrace运行（mauntrace()函数并非[总是必要][40]）的根本，因此Mtrace要求程序员至少改动源码一次。
|
||||
|
||||
了解需要在编译程序的时候带上-g选项（[GCC][41]和[G++][42]编译器均由提供），才能使调试工具在输出展示正确的行号。除此之外，有些程序（取决于源码体积有多大）可能会花很长时间进行编译。最后，带-g选项编译会增加了可执行文件的内存（因为提供了额外的调试信息），因此记得程序需要在测试结束，不带-g选项重新进行编译。
|
||||
|
||||
使用Mtrace，你需要掌握Linux环境变量的基本知识，因为在程序执行之前，需要把用户指定文件（mtrace()函数用以记载全部信息）的路径设置为环境变量MALLOC_TRACE的值。
|
||||
|
||||
Mtrace在检测内存泄漏和尝试释放未经过分配的内存方面存在局限。它不能检测其它内存相关问题如非法内存访问、使用未初始化内存。而且，[有人抱怨][43]Mtrace不是[线程安全][44]的。
|
||||
|
||||
### 总结 ###
|
||||
|
||||
不言自明，我在此讨论的每款内存调试器都有其优点和局限。所以，哪一款适合你取决于你所需要的特性，虽然有时候容易安装和使用也是一个决定因素。
|
||||
|
||||
要想捕获软件程序中的内存泄漏，Mtrace最适合不过了。它还可以节省时间。由于Linux系统已经预装了此工具，对于不能联网或者不可以下载第三方调试调试工具的情况，Mtrace也是极有助益的。
|
||||
|
||||
另一方面，相比Mtrace,，Dmalloc不仅能检测更多错误类型，还你呢个提供更多特性，比如运行时可配置、GDB集成。而且，Dmalloc不像这里所说的其它工具，它是线程安全的。更不用说它的详细资料了，这让Dmalloc成为初学者的理想选择。
|
||||
|
||||
虽然Memwatch的资料比Dmalloc的更加丰富，而且还能检测更多的错误种类，但是你只能在C语言写就的软件程序上使用它。一个让Memwatch脱颖而出的特性是它允许在你的程序源码中处理它的输出，这对于想要定制输出格式来说是非常有用的。
|
||||
|
||||
如果改动程序源码非你所愿，那么使用Electric Fence吧。不过，请记住，Electric Fence只能检测两种错误类型，而此二者均非内存泄漏。还有就是，需要了解GDB基础以最大程序发挥这款内存调试工具的作用。
|
||||
|
||||
Memcheck可能是这当中综合性最好的了。相比这里所说其它工具，它检测更多的错误类型，提供更多的特性，而且不需要你的源码做任何改动。但请注意，基本功能并不难上手，但是想要使用它的高级特性，就必须学习相关的专业知识了。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: http://www.computerworld.com/article/3003957/linux/review-5-memory-debuggers-for-linux-coding.html
|
||||
|
||||
作者：[Himanshu Arora][a]
|
||||
译者：[译者ID](https://github.com/soooogreen)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:http://www.computerworld.com/author/Himanshu-Arora/
|
||||
[1]:https://openclipart.org/detail/132427/penguin-admin
|
||||
[2]:https://en.wikipedia.org/wiki/Manual_memory_management
|
||||
[3]:http://dmalloc.com/
|
||||
[4]:https://www.owasp.org/index.php/Double_Free
|
||||
[5]:https://stuff.mit.edu/afs/sipb/project/gnucash-test/src/dmalloc-4.8.2/dmalloc.html#Fence-Post%20Overruns
|
||||
[6]:http://dmalloc.com/releases/notes/dmalloc-5.5.2.html
|
||||
[7]:http://www.gnu.org/software/gdb/
|
||||
[8]:http://dmalloc.com/docs/
|
||||
[9]:http://dmalloc.com/docs/latest/online/dmalloc_26.html#SEC32
|
||||
[10]:http://dmalloc.com/docs/latest/online/dmalloc_23.html#SEC29
|
||||
[11]:https://en.wikipedia.org/wiki/Memory_management#Dynamic_memory_allocation
|
||||
[12]:https://en.wikipedia.org/wiki/Segmentation_fault
|
||||
[13]:https://en.wikipedia.org/wiki/GNU_Compiler_Collection
|
||||
[14]:http://www.gnu.org/software/gdb/
|
||||
[15]:https://launchpad.net/ubuntu/+source/electric-fence/2.2.3
|
||||
[16]:http://valgrind.org/docs/manual/mc-manual.html
|
||||
[17]:http://valgrind.org/info/developers.html
|
||||
[18]:http://valgrind.org/
|
||||
[19]:http://valgrind.org/docs/manual/dist.news.html
|
||||
[20]:http://valgrind.org/docs/manual/mc-manual.html#mc-manual.suppfiles
|
||||
[21]:http://valgrind.org/docs/manual/mc-manual.html#mc-manual.mempools
|
||||
[22]:http://stackoverflow.com/questions/4642671/c-memory-allocators
|
||||
[23]:http://valgrind.org/docs/manual/mc-manual.html#mc-manual.monitor-commands
|
||||
[24]:http://valgrind.org/docs/manual/mc-manual.html#mc-manual.clientreqs
|
||||
[25]:http://valgrind.org/docs/manual/valgrind_manual.pdf
|
||||
[26]:http://sourceforge.net/p/valgrind/mailman/message/30292453/
|
||||
[27]:https://msdn.microsoft.com/en-us/library/ee798431%28v=cs.20%29.aspx
|
||||
[28]:http://www.computerworld.com/article/2484425/linux/5-free-linux-text-editors-for-programming-and-word-processing.html?nsdr=true&page=2
|
||||
[29]:http://valgrind.org/docs/manual/manual-core.html#manual-core.limits
|
||||
[30]:http://valgrind.org/info/
|
||||
[31]:http://www.linkdata.se/sourcecode/memwatch/
|
||||
[32]:http://www.cecalc.ula.ve/documentacion/tutoriales/WorkshopDebugger/007-2579-007/sgi_html/ch09.html
|
||||
[33]:http://c2.com/cgi/wiki?WildPointer
|
||||
[34]:https://en.wikipedia.org/wiki/Standard_streams#Standard_output_.28stdout.29
|
||||
[35]:http://www.gnu.org/software/libc/manual/html_node/Tracing-malloc.html
|
||||
[36]:https://www.gnu.org/software/libc/
|
||||
[37]:https://sourceware.org/git/?p=glibc.git;a=history;f=malloc/mtrace.c;h=df10128b872b4adc4086cf74e5d965c1c11d35d2;hb=HEAD
|
||||
[38]:https://sourceware.org/git/?p=glibc.git;a=history;f=malloc/mtrace.pl;h=0737890510e9837f26ebee2ba36c9058affb0bf1;hb=HEAD
|
||||
[39]:http://webcache.googleusercontent.com/search?q=cache:s6ywlLtkSqQJ:www.gnu.org/s/libc/manual/html_node/Tips-for-the-Memory-Debugger.html+&cd=1&hl=en&ct=clnk&gl=in&client=Ubuntu
|
||||
[40]:http://www.gnu.org/software/libc/manual/html_node/Using-the-Memory-Debugger.html#Using-the-Memory-Debugger
|
||||
[41]:http://linux.die.net/man/1/gcc
|
||||
[42]:http://linux.die.net/man/1/g++
|
||||
[43]:https://sourceware.org/ml/libc-help/2014-05/msg00008.html
|
||||
[44]:https://en.wikipedia.org/wiki/Thread_safety
|
||||
@ -0,0 +1,93 @@
|
||||
安卓编年史
|
||||
================================================================================
|
||||
|
||||
和之前完全不同的市场设计。以上是分类，特色，热门应用以及应用详情页面。
|
||||
Ron Amadeo 供图
|
||||
|
||||
这些截图给了我们冰淇淋三明治中新版操作栏的第一印象。几乎所有的应用顶部都有一条栏，带有应用图标，当前界面标题，一些功能按钮，右边还有一个菜单按钮。这个右对齐的菜单按钮被称为“更多操作”，因为里面存放着无法放置到主操作栏的项目。不过更多操作菜单并不是固定不变的，它给了操作栏节省了更多的屏幕空间——比如在横屏模式或在平板上时，更多操作菜单的项目会像通常的按钮一样显示在操作栏上。
|
||||
|
||||
冰淇凌三明治中新增了“滑动标签页”设计，替换掉了谷歌之前推行的2×3方阵导航屏幕。一个标签页栏放置在了操作栏下方，位于中间的标签显示的是当前页面，左右侧的两个标签显示的是对应的当前页面的左右侧页面。向左右滑动可以切换标签页，或者你可以点击指定页面的标签跳转过去。
|
||||
|
||||
应用详情页面有个很赞的设计，在应用截图后，会根据你关于那个应用的历史动态地重新布局页面。如果你从来没有安装过该应用，应用描述会优先显示。如果你曾安装过这个应用，第一部分将会是评价栏，它会邀请你评价该应用或者提醒你上次你安装该应用时的评价是什么。之前使用过的应用页面第二部分是“新特性”，因为一个老用户最关心的应该是应用有什么变化。
|
||||
|
||||
|
||||
最近应用和浏览器和蜂巢中的类似，但是是小号的。
|
||||
Ron Amadeo 供图
|
||||
|
||||
最近应用的电子风格外观被移除了。略缩图周围的蓝色的轮廓线被去除了，同时去除的还有背景怪异的，不均匀的蓝色光晕。它现在看起来是个中立型的界面，在任何时候看起来都很舒适。
|
||||
|
||||
浏览器尽了最大的努力把标签页体验带到手机上来。多标签浏览受到了关注，操作栏上引入的一个标签页按钮会打开一个类似最近应用的界面，显示你打开的标签页，而不是浪费宝贵的屏幕空间引入一个标签条。从功能上来说，这个和之前的浏览器中的“窗口”视图没什么差别。浏览器最佳的改进是菜单中的“请求桌面版站点”选项，这让你可以从默认的移动站点视图切换到正常站点。浏览器展示了谷歌的操作栏设计的灵活性，尽管这里没有左上角的应用图标，功能上来说和其他的顶栏设计相似。
|
||||
|
||||
|
||||
Gmail 和 Google Talk —— 它们和蜂巢中的相似，但是更小！
|
||||
Ron Amadeo 供图
|
||||
|
||||
Gmail 和 Google Talk 看起来都像是之前蜂巢中的设计的缩小版，但是有些小调整让它们在小屏幕上表现更佳。Gmail 以双操作栏为特色——一个在屏幕顶部，一个在底部。顶部操作栏显示当前文件夹，账户，以及未读消息数目，点击顶栏可以打开一个导航菜单。底部操作栏有你期望出现在更多操作中的选项。使用双操作栏布局是为了在界面显示更多的按钮，但是在横屏模式下纵向空间有限，双操作栏就是合并成一个顶部操作栏。
|
||||
|
||||
在邮件视图下，往下滚动屏幕时蓝色栏有“粘性”。它会固定在屏幕顶部，所以你一直可以看到该邮件是谁写的，回复它，或者给它加星标。一旦处于邮件消息界面，底部细长的，深灰色栏会显示你当前在收件箱（或你所在的某个列表）的位置，并且你可以向左或向右滑动来切换到其他邮件。
|
||||
|
||||
Google Talk 允许你像在 Gmail 中那样左右滑动来切换聊天窗口，但是这里显示栏是在顶部。
|
||||
|
||||
|
||||
新的拨号和来电界面，都是姜饼以来我们还没见过的。
|
||||
Ron Amadeo 供图
|
||||
|
||||
因为蜂巢只给平板使用，所以一些界面设计直接超前于姜饼。冰淇淋三明治的新拨号界面就是如此，黑色和蓝色相间，并且使用了可滑动切换的小标签。尽管冰淇淋三明治终于做了对的事情并将电话主体和联系人独立开来，但电话应用还是有它自己的联系人标签。现在有两个地方可以看到你的联系人列表——一个有着暗色主题，另一个有着亮色主题。由于实体搜索按钮不再是硬性要求，底部的按钮栏的语音信息快捷方式被替换为了搜索图标。
|
||||
|
||||
谷歌几乎就是把来电界面做成了锁屏界面的镜像，这意味着冰淇淋三明治有着一个环状解锁设计。除了通常的接受和挂断选项，圆环的顶部还添加了一个按钮，让你可以挂断来电并给对方发送一条预先定义好的信息。向上滑动并选择一条信息如“现在无法接听，一会回电”，相比于一直响个不停的手机而言这样做的信息交流更加丰富。
|
||||
|
||||
|
||||
蜂巢没有文件夹和信息应用，所以这里是冰淇淋三明治和姜饼的对比。
|
||||
Ron Amadeo 供图
|
||||
|
||||
现在创建文件夹更加方便了。在姜饼中，你得长按屏幕，选择“文件夹”选项，再点击“新文件夹”。在冰淇淋三明治中，你只要将一个图标拖拽到另一个图标上面，就会自动创建一个文件夹，并包含这两个图标。这简直不能更简单了，比寻找隐藏的长按命令容易多了。
|
||||
|
||||
设计上也有很大的改进。姜饼使用了一个通用的米黄色文件夹图标，但冰淇淋三明治直接显示出了文件夹中的头三个应用，把它们的图标叠在一起，在外侧画一个圆圈，并将其设置为文件夹图标。打开文件夹容器将自动调整大小以适应文件夹中的应用图标数目，而不是显示一个全屏的，大部分都是空的对话框。这看起来好得多得多。
|
||||
|
||||
|
||||
Youtube 转换到一个更加现代的白色主题，使用了列表视图替换疯狂的 3D 滚动视图。
|
||||
Ron Amadeo 供图
|
||||
|
||||
Youtube 经过了完全的重新设计，看起来没那么像是来自黑客帝国的产物，更像是，嗯，Youtube。它现在就是一个简单的垂直滚动的白色视频列表，就像网站的那样。在你手机上制作视频受到了重视，操作栏的第一个按钮专用于拍摄视频。奇怪的是，不同的界面左上角使用了不同的 Youtube 标志，在水平的 Youtube 标志和方形标志之间切换。
|
||||
|
||||
Youtube 几乎在所有地方都使用了滑动标签页。它们被放置在主页面以在浏览和账户间切换，放置在视频页面以在评论，介绍和相关视频之间切换。4.0 版本的应用显示出 Google+ Youtube 集成的第一个信号，通常的评分按钮旁边放置了 “+1” 图标。最终 Google+ 会完全占据 Youtube，将评论和作者页面变成 Google+ 活动。
|
||||
|
||||
|
||||
冰淇淋三明治试着让事情对所有人都更加简单。这里是数据使用量追踪，打开许多数据的新开发者选项，以及使用向导。
|
||||
Ron Amadeo 供图
|
||||
|
||||
数据使用量允许用户更轻松地追踪和控制他们的数据使用。主页面显示一个月度使用量图表，用户可以设置数据使用警告值或者硬性使用限制以避免超量使用产生费用。所有的这些只需简单地拖动橙色和红色水平限制线在图表上的位置即可。纵向的白色把手允许用户选择图表上的一段指定时间段。在页面底部，选定时间段内的数据使用量又细分到每个应用，所以用户可以选择一个数据使用高峰并轻松地查看哪个应用在消耗大量流量。当流量紧张的时候，更多操作按钮中有个限制所有后台流量的选项。设置之后只用在前台运行的程序有权连接互联网。
|
||||
|
||||
开发者选项通常只有一点点设置选项，但是在冰淇淋三明治中，这部分有非常多选项。谷歌添加了所有类型的屏幕诊断显示浮层来帮助开发者理解他们的应用中发生了什么。你可以看到 CPU 使用率，触摸点位置，还有视图界面更新。还有些选项可以更改系统功能，比如控制动画速度，后台处理，以及 GPU 渲染。
|
||||
|
||||
安卓和 iOS 之间最大的区别之一就是应用抽屉界面。在冰淇淋三明治对更加用户友好的追求下，设备第一次初始化启动会启动一个小教程，向用户展示应用抽屉的位置以及如何将应用图标从应用抽屉拖拽到主屏幕。随着实体菜单按键的移除和像这样的改变，安卓 4.0 做了很大的努力变得对新智能手机用户和转换过来的用户更有吸引力。
|
||||
|
||||
|
||||
“触摸分享”NFC 支持，Google Earth，以及应用信息，让你可以禁用垃圾软件。
|
||||
|
||||
冰淇淋三明治内置对 [NFC][1] 的完整支持。尽管之前的设备，比如 Nexus S 也拥有 NFC，得到的支持是有限的并且系统并不能利用芯片做太多事情。4.0 添加了一个“Android Beam”功能，两台拥有 NFC 的安卓 4.0 设备可以借此在设备间来回传输数据。NFC 会传输关于此事屏幕显示的数据，因此在手机显示一个网页的时候使用该功能会将该页面传送给另一部手机。你还可以发送联系人信息，方向导航，以及 Youtube 链接。当两台手机放在一起时，屏幕显示会缩小，点击缩小的界面会发送相关信息。
|
||||
|
||||
I在安卓中，用户不允许删除系统应用，以保证系统完整性。运营商和 OEM 利用该特性并开始将垃圾软件放入系统分区，经常有一些没用的应用存在系统中。安卓 4.0 允许用户禁用任何不能被卸载的应用，意味着该应用还存在于系统中但是不显示在应用抽屉里并且不能运行。如果用户愿意深究设置项，这给了他们一个简单的途径来拿回手机的控制权。
|
||||
|
||||
安卓 4.0 可以看做是现代安卓时代的开始。大部分这时发布的谷歌应用只能在安卓 4.0 及以上版本运行。4.0 还有许多谷歌想要好好利用的新 API——至少最初想要——对 4.0 以下的版本的支持就有限了。在冰淇淋三明治和蜂巢之后，谷歌真的开始认真对待软件设计。在2012年1月，谷歌[最终发布了][2] *Android Design*，一个教安卓开发者如何创建符合安卓外观和感觉的应用的设计指南站点。这是 iOS 在有第三方应用支持开始就在做的事情，苹果还严肃地对待应用的设计，不符合指南的应用都被 App Store 拒之门外。安卓三年以来谷歌没有给出任何公共设计规范文档的事实，足以说明事情有多糟糕。但随着在 Duarte 掌控下的安卓设计革命，谷歌终于发布了基本设计需求。
|
||||
|
||||
----------
|
||||
|
||||
|
||||
|
||||
[Ron Amadeo][a] / Ron是Ars Technica的评论编缉，专注于安卓系统和谷歌产品。他总是在追寻新鲜事物，还喜欢拆解事物看看它们到底是怎么运作的。
|
||||
|
||||
[@RonAmadeo][t]
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: http://arstechnica.com/gadgets/2014/06/building-android-a-40000-word-history-of-googles-mobile-os/20/
|
||||
|
||||
译者：[alim0x](https://github.com/alim0x) 校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
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://arstechnica.com/gadgets/2011/02/near-field-communications-a-technology-primer/
|
||||
[2]:http://arstechnica.com/business/2012/01/google-launches-style-guide-for-android-developers/
|
||||
[a]:http://arstechnica.com/author/ronamadeo
|
||||
[t]:https://twitter.com/RonAmadeo
|
||||
@ -0,0 +1,39 @@
|
||||
# 使用SystemBack备份你的Ubuntu/Linux Mint（系统还原）
|
||||
|
||||
系统还原对于任何一款允许用户还原电脑到之前状态（包括文件系统，安装的应用，以及系统设置）的操作系统来说，都是必备功能，可以处理系统故障以及其他的问题。有的时候安装一个程序或者驱动可能让你的系统黑屏。系统还原则让你电脑里面的系统文件（译者注：是系统文件，并非普通文件，详情请看**注意**部分）和程序恢复到之前工作正常时候的状态，进而让你远离那让人头痛的排障过程了。而且它也不会影响你的文件，照片或者其他数据。简单的系统备份还原工具[Systemback](https://launchpad.net/systemback)让你很容易地创建系统备份以及用户配置文件。如果遇到问题，你可以傻瓜式还原。它还有一些额外的特征包括系统复制，系统安装以及Live系统创建。
|
||||
|
||||
截图
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
**注意**:使用系统还原不会还原你的文件，音乐，电子邮件或者其他任何类型的私人文件。对不同用户来讲，这既是优点又是缺点。坏消息是它不会还原你意外删除的文件，不过你可以通过一个文件恢复程序来解决这个问题。如果你的计算机上没有系统还原点，那么系统还原工具就不会奏效了。（最后一句没有太理解）
|
||||
|
||||
> > >适用于Ubuntu 15.10 Wily/16.04/15.04 Vivid/14.04 Trusty/Linux Mint 14.x/其他Ubuntu衍生版，打开终端，将下面这些命令复制过去：
|
||||
|
||||
终端命令：
|
||||
|
||||
```
|
||||
sudo add-apt-repository ppa:nemh/systemback
|
||||
sudo apt-get update
|
||||
sudo apt-get install systemback
|
||||
|
||||
```
|
||||
|
||||
大功告成。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: http://www.noobslab.com/2015/11/backup-system-restore-point-your.html
|
||||
|
||||
译者：[DongShuaike](https://github.com/DongShuaike)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[1]:https://launchpad.net/systemback
|
||||
@ -0,0 +1,107 @@
|
||||
Linux 教学之物理模拟
|
||||
================================================================================
|
||||
|
||||
|
||||
[Linux 学习系列][1]的所有文章：
|
||||
|
||||
- [Linux 教学之教你练打字][2]
|
||||
- [Linux 教学之物理模拟][3]
|
||||
- [Linux 教学之教你玩音乐][4]
|
||||
- [Linux 教学之两款地理软件][5]
|
||||
- [Linux 教学之掌握数学][6]
|
||||
|
||||
引言：Linux 提供大量的教学软件和工具，面向各个年级段以及年龄段，提供大量学科的练习实践，其中大多数是可以与用户进行交互的。本“Linux 教学”系列就来介绍一些教学软件。
|
||||
|
||||
物理是一个有趣的课题，证据就是任何物理课程都可以用具体的图片演示给你看。能看到物理变化过程是一个很妙的体验，特别是你不需要到教室就能体验到。Linux 上有很多很好的科学软件来为你提供这种美妙感觉，本篇文章只着重介绍其中几种。
|
||||
|
||||
### 1. Step ###
|
||||
|
||||
[Step][7] 是一个交互型物理模拟器，KDEEdu[8]（KDE 教育）项目的一部分。没人会比它的作者更了解它的作用。在项目官网主页上写着“[Step] 是这样玩的：你放点东西进来，添加一些力（地心引力或者弹簧），然后点击‘模拟’按钮，这款软件就会为你模拟这个物体在真实世界的物理定律影响下的运动状态。你可以改变物体或力的属性（允许在模拟过程中进行修改），然后观察不同属性下产生的现象。Step 可以让你从体验中学习物理！”
|
||||
|
||||
Step 依赖 Qt 以及其他一些 KDE 所依赖的软件，正是由于像 KDEEdu 之类的项目存在，才使得 KDE 变得如此强大，当然，你可能需要忍受由此带来的庞大的桌面系统。
|
||||
|
||||
Debian 的源中包含了 step 软件，终端下运行以下命令安装：
|
||||
|
||||
sudo apt-get install step
|
||||
|
||||
在 KDE 环境下，它只需要很少的依赖，几秒钟就能安装完成。
|
||||
|
||||
Step 有个简单的交互界面，你进去后直接可以进行模拟操作。
|
||||
|
||||
|
||||
|
||||
你会发现所有物品在屏幕左边，包括不同的质点，空气，不同形状的物体，弹簧，以及不同的力（见1区域） 。如果你选中一个物体，屏幕右边会出现简短的描述信息（见2区域），以及你创造的世界的介绍（主要介绍这个世界中包含的物体）（见3区域），以及你当前选中的物体的属性（见4区域），以及你的操作历史（见5区域）。
|
||||
|
||||
|
||||
|
||||
一旦你放好了所有物体，点击下“模拟”按钮，可以看到物体与物体之间的相互作用。
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
想要更多了解 Step，按 F1 键，KDE 帮助中心会打印详细的软件操作手册。
|
||||
|
||||
### 2. Lightspeed ###
|
||||
|
||||
Lightspeed 是一个简单的基于 GTK+ 和 OpenGL 的模拟器，可以模拟一个高速移动的物体被观测到的现象。这个模拟器的理论基础是爱因斯坦的狭义相对论，在 Lightspeed 的 [srouceforge 页面][9]上，他们这样介绍：当一个物体被加速到几千公里每秒，它就会表现得扭曲和褪色；当物体被不断加速到接近光速（299,792,458 m/s）时，这个现象会越来越明显，并且在不同方向观察这个物体的扭曲方式，会得到完全不一样的结果。
|
||||
|
||||
受到相对速度影响的现象如下（LCTT 译注：都可以从“光速不变”理论推导出来）：
|
||||
|
||||
- **洛伦兹收缩** —— 物体看起来变短了
|
||||
- **多普乐红移/蓝移** —— 物体的颜色变了
|
||||
- **前灯效应** —— 物体的明暗变化（LCTT 译注：当物体接近光速移动时，会在它前进的方向强烈地辐射光子，从这个角度看，物体会变得很亮，相反，从物体背后观察，会发现它很暗）
|
||||
- **光行差效应** —— 物体扭曲变形了
|
||||
|
||||
Lightspeed 有 Debian 的源，执行下面的命令来安装：
|
||||
|
||||
sudo apt-get install lightspeed
|
||||
|
||||
用户界面非常简单，里边有一个物体（你可以从 sourceforge 下载更多形状的物体）沿着 x 轴运动（按下 A 键或在菜单栏 object 项目的 Animation 选项设置，物体就会开始运动）。
|
||||
|
||||
|
||||
|
||||
你可以滑动右边的滑动条来控制物体移动的速度。
|
||||
|
||||
|
||||
|
||||
其他一些简单的控制器可以让你获得更多的视觉效果。
|
||||
|
||||
|
||||
|
||||
点击界面并拖动鼠标可以改变物体视角，在 Camera 菜单下可以修改背景颜色或者物体的图形模式，以及其他效果。
|
||||
|
||||
### 特别推荐： Physion ###
|
||||
|
||||
Physion 是个非常有趣并且美观的物理模拟软件，比上面介绍的两款软件都好玩好看。可惜在写本文章的时候它的[官网][10]出现问题了，下载页面无法使用。
|
||||
|
||||
从他们放在 Youtube 上的视频来看，Physion 还是值得我们下载下来玩玩的。在官网恢复之前，我们只能看看演示视频了。
|
||||
|
||||
注：youtube 视频
|
||||
<iframe frameborder="0" src="//www.youtube.com/embed/P32UHa-3BfU?autoplay=1&autohide=2&border=0&wmode=opaque&enablejsapi=1&controls=0&showinfo=0" id="youtube-iframe"></iframe>
|
||||
|
||||
你有其他 Linux 下的好玩的物理模拟、演示、教学软件吗？如果有，请在评论处分享给我们。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.maketecheasier.com/linux-physics-simulation/
|
||||
|
||||
作者：[Attila Orosz][a]
|
||||
译者：[bazz2](https://github.com/bazz2)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://www.maketecheasier.com/author/attilaorosz/
|
||||
[1]:https://www.maketecheasier.com/series/learn-with-linux/
|
||||
[2]:https://www.maketecheasier.com/learn-to-type-in-linux/
|
||||
[3]:https://www.maketecheasier.com/linux-physics-simulation/
|
||||
[4]:https://www.maketecheasier.com/linux-learning-music/
|
||||
[5]:https://www.maketecheasier.com/linux-geography-apps/
|
||||
[6]:https://www.maketecheasier.com/learn-linux-maths/
|
||||
[7]:https://edu.kde.org/applications/all/step
|
||||
[8]:https://edu.kde.org/
|
||||
[9]:http://lightspeed.sourceforge.net/
|
||||
[10]:http://www.physion.net/
|
||||
Loading…
Reference in New Issue
Block a user