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What is the best way to ensure only one instance of a Bash script is running? [duplicate]
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If the script is the same across all users, you can use a lockfile approach. If you acquire the lock, proceed else show a message and exit.
As an example:
[Terminal #1] $ lockfile -r 0 /tmp/the.lock
[Terminal #1] $
[Terminal #2] $ lockfile -r 0 /tmp/the....
Iterate a list as pair (current, next) in Python
...(b, None)
return itertools.izip(a, b)
How this works:
First, two parallel iterators, a and b are created (the tee() call), both pointing to the first element of the original iterable. The second iterator, b is moved 1 step forward (the next(b, None)) call). At this point a points to s0 and b...
Specifying rails version to use when creating a new application
I have two versions of rails (2.1.0 and 2.2.2) installed in my computer.
7 Answers
7
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Android ACTION_IMAGE_CAPTURE Intent
...works just fine if we leave out the EXTRA_OUTPUT extra and returns the small Bitmap image. However, if we putExtra(EXTRA_OUTPUT,...) on the intent before starting it, everything works until you try to hit the "Ok" button in the camera app. The "Ok" button just does nothing. The camera app stays ...
Coalesce function for PHP?
...HP 7 introduced a real coalesce operator:
echo $_GET['doesNotExist'] ?? 'fallback'; // prints 'fallback'
If the value before the ?? does not exists or is null the value after the ?? is taken.
The improvement over the mentioned ?: operator is, that the ?? also handles undefined variables without...
Get IP address of visitors using Flask for Python
...emote_addr)
When proxies, such as nginx, forward addresses, they typically include the original IP somewhere in the request headers.
Update See the flask-security implementation. Again, review the documentation about ProxyFix before implementing. Your solution may vary based on your particular...
Django: Get model from string?
...d in 1.9) in favor of the the new application loading system.
-- Scott Woodall
Found it. It's defined here:
from django.db.models.loading import get_model
Defined as:
def get_model(self, app_label, model_name, seed_cache=True):
...
Autoreload of modules in IPython [duplicate]
Is there a way to have IPython automatically reload all changed code? Either before each line is executed in the shell or failing that when it is specifically requested to. I'm doing a lot of exploratory programming using IPython and SciPy and it's quite a pain to have to manually reload each module...
What is the reason why “synchronized” is not allowed in Java 8 interface methods?
...t seem sensible to extend this semantics to default methods as well; after all, they are instance methods with a receiver too. (Note that synchronized methods are entirely a syntactic optimization; they're not needed, they're just more compact than the corresponding synchronized block. There's a r...
Making a WinForms TextBox behave like your browser's address bar
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First of all, thanks for answers! 9 total answers. Thank you.
Bad news: all of the answers had some quirks or didn't work quite right (or at all). I've added a comment to each of your posts.
Good news: I've found a way to make it wo...