大约有 48,000 项符合查询结果（耗时：0.0675秒） [XML]
Check Whether a User Exists
...
You can also check user by id command.
id -u name gives you the id of that user.
if the user doesn't exist, you got command return value ($?)1
And as other answers pointed out: if all you want is just to check if the user exists, use if with id directly, as i...
What is the use case of noop [:] in bash?
...ver'
done
It's traditional to use : when the shell syntax requires a command but you have nothing to do.
while keep_waiting; do
: # busy-wait
done
The : builtin dates all the way back to the Thompson shell, it was present in Unix v6. : was a label indicator for the Thompson shell's goto state...
What's the best way to set a single pixel in an HTML5 canvas?
...
There are two best contenders:
Create a 1×1 image data, set the color, and putImageData at the location:
var id = myContext.createImageData(1,1); // only do this once per page
var d = id.data; // only do this once per page
d[0] = r;
d[1] = g;
d[2] = b;
d[3] = a;
...
Aliases in Windows command prompt
...ith the following steps,
Create a .bat or .cmd file with your DOSKEY commands.
Run regedit and go to HKEY_CURRENT_USER\Software\Microsoft\Command Processor
Add String Value entry with the name AutoRun and the full path of your .bat/.cmd file.
For example, %USERPROFILE%\alias.cmd, replacing the i...
Maven build failed: “Unable to locate the Javac Compiler in: jre or jdk issue”
...
You could try updating the JDK Eclipse is using, as follows:
Add and set the JRE in menu Window → Preferences... → Java → Installed JREs:
JRE type: Standard VM JRE
Name: jdk1.6.0_18
JRE home directory: C:\Program Files (x86)\Java\jdk1.6.0_18
If this is not the case, it's possible ...
Traits in PHP – any real world examples/best practices? [closed]
...its have been one of the biggest additions for PHP 5.4. I know the syntax and understand the idea behind traits, like horizontal code re-use for common stuff like logging, security, caching etc.
...
Proper REST response for empty table?
...fused as an author of a client for your application if I got a 200 one day and a 404 the next day just because someone happened to remove a couple of users. What am I supposed to do? Is my URL wrong? Did someone change the API and neglect to leave a redirection.
Why not 204 (No Content) ?
Here's a...
Merging: Hg/Git vs. SVN
I often read that Hg (and Git and...) are better at merging than SVN but I have never seen practical examples of where Hg/Git can merge something where SVN fails (or where SVN needs manual intervention). Could you post a few step-by-step lists of branch/modify/commit/...-operations that show where S...
In PowerShell, how do I define a function in a file and call it from the PowerShell commandline?
...
Try this on the PowerShell command line:
. .\MyFunctions.ps1
A1
The dot operator is used for script include.
share
|
improve this answer
|
...
Can every recursion be converted into iteration?
...u always turn a recursive function into an iterative one? Yes, absolutely, and the Church-Turing thesis proves it if memory serves. In lay terms, it states that what is computable by recursive functions is computable by an iterative model (such as the Turing machine) and vice versa. The thesis does ...