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Appending a line to a file only if it does not already exist
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Just keep it simple :)
grep + echo should suffice:
grep -qxF 'include "/configs/projectname.conf"' foo.bar || echo 'include "/configs/projectname.conf"' >> foo.bar
-q be quiet
-x match the whole line
-F pattern is a plain st...
c++11 Return value optimization or move? [duplicate]
...recisely when copy elision is allowed.
Your second version actively prohibits copy elision. The first version is universally better.
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What does “all” stand for in a makefile?
I read some tutorials concerning Makefiles but for me it is still unclear for what the target "all" stands for and what it does.
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Xcode: Build Failed, but no error messages
...uilding fine for the last three months, but suddenly, when I try to build, it says "Build failed", but does not show any errors on the triangle exclamation mark tab, nor does it give a reason when it pops up build failed.
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Unusual shape of a textarea?
.... I think this one is currently (in 2013) the one which can be compatible with the largest number of browsers, because it doesn't need any CSS3 properties. However, the method will not work on browsers which doesn't support contentdeditable, be careful.
Solution with a div contenteditable
As propo...
Correct Bash and shell script variable capitalization
I run across many shell scripts with variables in all caps, and I've always thought that there is a severe misunderstanding with that. My understanding is that, by convention (and perhaps by necessity long ago), environment variables are in all-caps.
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Defining an abstract class without any abstract methods
Can I define an abstract class without adding an abstract method?
12 Answers
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If isset $_POST
I have a form on one page that submits to another page. There, it checks if the input mail is filled. If so then do something and if it is not filled, do something else. I don't understand why it always says that it is set, even if I send an empty form. What is missing or wrong?
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Getting the location from an IP address [duplicate]
I want to retrieve information like the city, state, and country of a visitor from their IP address, so that I can customize my web page according to their location. Is there a good and reliable way to do this in PHP? I am using JavaScript for client-side scripting, PHP for server-side scripting, an...
What is pip's equivalent of `npm install package --save-dev`?
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There isn't an equivalent with pip.
Best way is to pip install package && pip freeze > requirements.txt
You can see all the available options on their documentation page.
If it really bothers you, it wouldn't be too difficult to write a ...