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How to add /usr/local/bin in $PATH on Mac
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While you can do this, it's not the OS X way. Paths on OS X are built using /usr/libexec/path_helper, called from the default /etc/profile. Start at man path_helper then add your paths in files in /etc/paths.d. You will find that pretty much every path setting ...
In Typescript, How to check if a string is Numeric
...y to convert a string to a number is with Number, not parseFloat.
Number('1234') // 1234
Number('9BX9') // NaN
You can also use the unary plus operator if you like shorthand:
+'1234' // 1234
+'9BX9' // NaN
Be careful when checking against NaN (the operator === and !== don't work as expected wi...
What is a mutex?
...ople hoilding the mu.. chicken are competing threads. The Moderator is the OS. When people requests the chicken, they do a lock request. When you call mutex.lock(), your thread stalls in lock() and makes a lock request to the OS. When the OS detects that the mutex was released from a thread, it mere...
How can I shuffle the lines of a text file on the Unix command line or in a shell script?
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You can use shuf. On some systems at least (doesn't appear to be in POSIX).
As jleedev pointed out: sort -R might also be an option. On some systems at least; well, you get the picture. It has been pointed out that sort -R doesn't really shuffle but instead sort items according to their hash ...
What's the meaning of Base SDK, iOS deployment target, Target, and Project in xcode
...base SDK to 7, what does it mean? It could mean that the app would run on iOS 7. But that's what iOS deployment target is for.
...
How to call Base Class's __init__ method from the child class? [duplicate]
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123
You could use super(ChildClass, self).__init__()
class BaseClass(object):
def __init__(se...
what happens when you type in a URL in browser [closed]
...is is an extremely rough and oversimplified sketch, assuming the simplest possible HTTP request (no HTTPS, no HTTP2, no extras), simplest possible DNS, no proxies, single-stack IPv4, one HTTP request only, a simple HTTP server on the other end, and no problems in any step. This is, for most contempo...
What is memory fragmentation?
...and you can't, even though you appear to have enough memory free. Another possible consequence is the inability of the process to release memory back to the OS (because each of the large blocks it has allocated from the OS, for malloc etc. to sub-divide, has something left in it, even though most of...
Google Tag Manager 入门指南 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...Of(“/jp/”) == 0) { … }
通配符,如:文章的地址:/article_123:
If (/article_\d+/.test(a)) { … } // 这儿用正则表达式来匹配末尾的数字。
实际的匹配条件会有很多种,这对于没有代码基础的网站分析人员可真是一种挑战啊,另外写...
How to remove a field completely from a MongoDB document?
... looks like this:
{
name: 'book',
tags: [
{
words: ['abc','123'],
lat: 33,
long: 22
}, {
words: ['def','456'],
lat: 44,
long: 33
}
]
}
To remove the column words from the embedded document, do this:
db.example.update(
{'tags': {'$exists':...
