大约有 6,000 项符合查询结果（耗时：0.0164秒） [XML]
Understanding :source option of has_one/has_many through of Rails
...'ve chosen to namespace the Dog::Breed, because we want to access Dog.find(123).breeds as a nice and convenient association.
Now, if we now want to create a has_many :dog_breeds, :through => :dogs association on Pet, we suddenly have a problem. Rails won't be able to find a :dog_breeds associati...
Converting newline formatting from Mac to Windows
...
In conclusion, simply replace every occurence of \n by \r\n.
Both unix2dos and dos2unix are not by default available on Mac OSX.
Fortunately, you can simply use Perl or sed to do the job:
sed -e 's/$/\r/' inputfile > outputfile # UNIX to DOS (adding CRs)
sed -e 's/\r$//' input...
How do I create a unique constraint that also allows nulls?
...et_AllowNull
UNIQUE (TicketID, TicketUnique);
If IssueID 1 has ticket 123, the UNIQUE constraint will be on values (123, NULL). If IssueID 2 has no ticket, it will be on (NULL, 2). Some thought will show that this constraint cannot be duplicated for any row in the table, and still allows multip...
How do I deploy Node.js applications as a single executable file? [duplicate]
Supposed I have written a Node.js application, and I now would like to distribute it. Of course, I want to make it easy for the user, hence I do not want him to install Node.js, run npm install and then manually type node app.js .
...
Why is Linux called a monolithic kernel?
...ion, etc.) are a tight knit group sharing the same space. This directly opposes a microkernel.
A microkernel prefers an approach where core functionality is isolated from system services and device drivers (which are basically just system services). For instance, VFS (virtual file system) and block...
Shell脚本编程30分钟入门 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...文本编辑器和一个能解释执行的脚本解释器就可以了。
OS
当前主流的操作系统都支持shell编程，本文档所述的shell编程是指Linux下的shell，讲的基本都是POSIX标准下的功能，所以，也适用于Unix及BSD（如Mac OS）。
Linux
Linux默认安...
Detect if device is iOS
I'm wondering if it's possible to detect whether a browser is running on iOS, similar to how you can feature detect with Modernizr (although this is obviously device detection rather than feature detection).
...
How can I find the version of the Fedora I use?
...d the login banners … I typically edit mine, and so, it seems, do many (most) corporate IT departments... :-(
– BRPocock
Dec 2 '11 at 16:05
8
...
Install autoreconf on OS X v10.7 (Lion)?
...
brew isn't included with OSX, but you can get it here: mxcl.github.com/homebrew
– RobM
Apr 25 '12 at 11:45
...
Get users by name property using Firebase
...:
Write to Firebase with a unique, known key:
ref.child('users').child('123').set({ "first_name": "rob", "age": 28 })
Append to lists with an auto-generated key that will automatically sort by time written:
ref.child('users').push({ "first_name": "rob", "age": 28 })
Listen for changes in data ...