大约有 40,000 项符合查询结果（耗时：0.0751秒） [XML]
How can I check if a program exists from a Bash script?
...type or command are way cheaper), you can also rely on the builtins to actually do what you want, while the effects of external commands can easily vary from system to system.
Why care?
Many operating systems have a which that doesn't even set an exit status, meaning the if which foo won't even wor...
How to check if APK is signed or “debug build”?
... java.security.cert.CertificateException and android.content.pm.Signature. All other classes don't present multiple matches for me
– Christian García
Nov 29 '12 at 13:55
...
difference between fork and branch on github
If I fork a project that's hosted on github. Do I fork all the branches? How do I know which branch my fork is based on? In other words which branch will be downloaded to my PC?
...
Add Foreign Key to existing table
...
To add a foreign key (grade_id) to an existing table (users), follow the following steps:
ALTER TABLE users ADD grade_id SMALLINT UNSIGNED NOT NULL DEFAULT 0;
ALTER TABLE users ADD CONSTRAINT fk_grade_id FOREIGN KEY (grade_id) REFERENCES grades(id);
...
instantiate a class from a variable in PHP?
...you work with namespace, put the current namespace into the string: $var = __NAMESPACE__ . '\\' . $var . 'Class';
– bastey
Sep 2 '13 at 13:28
...
The Ruby %r{ } expression
...
%r{} is equivalent to the /.../ notation, but allows you to have '/' in your regexp without having to escape them:
%r{/home/user}
is equivalent to:
/\/home\/user/
This is only a syntax commodity, for legibility.
Edit:
Note that you can use almost any non-alphabet...
Uninstall / remove a Homebrew package including all its dependencies
I have a Homebrew formula that I wish to uninstall/remove along with all its dependencies, skipping packages whom other packages depend upon (a.k.a. Cascading package removal in Package manager parlance).
...
Could not load file or assembly 'System.Data.SQLite'
I've installed ELMAH 1.1 .Net 3.5 x64 in my ASP.NET project and now I'm getting this error (whenever I try to see any page):
...
How to copy text from Emacs to another application on Linux
When I cut (kill) text in Emacs 22.1.1 (in its own window on X, in KDE, on Kubuntu), I can't paste (yank) it in any other application.
...
When should I use @classmethod and when def method(self)?
...fine functions in classes. The author seems to use them both very intentionally. The first one is one I myself use a lot:
3...