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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....
C++ Dynamic Shared Library on Linux
...were for a plugin system, you would use MyClass as a base class and define all the required functions virtual. The plugin author would then derive from MyClass, override the virtuals and implement create_object and destroy_object. Your main application would not need to be changed in any way.
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C++ Best way to get integer division and remainder
... experiment with g++ 6.3.0 on x86_64 revealed that with no optimization at all, you get two idivl instructions, but with -O1 or greater, you get one. As the manual says, “Without any optimization option … Statements are independent”.
– Tom Zych
Oct 15 '17...
Importing from a relative path in Python
...his method is still commonly used in some situations, where you aren't actually ever 'installing' your package. For example, it's popular with Django users.
You can add Common/ to your sys.path (the list of paths python looks at to import things):
import sys, os
sys.path.append(os.path.join(os.p...
What is __pycache__?
...'s files, respectively.
As a programmer, you can largely just ignore it... All it does is make your program start a little faster. When your scripts change, they will be recompiled, and if you delete the files or the whole folder and run your program again, they will reappear (unless you specificall...
What is the fastest way to send 100,000 HTTP requests in Python?
...rogram correctly. Has anyone come across a similar problem? I guess generally I need to know how to perform thousands of tasks in Python as fast as possible - I suppose that means 'concurrently'.
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How to draw a line in android
...rself just simple and clean add the line in xml.
<View
android:layout_width="match_parent"
android:layout_height="1dp"
android:background="@android:color/black" />
The example code I provided will generate a line that fills the screen in width and has a height of one dp.
If you have ...
Dependent DLL is not getting copied to the build output folder in Visual Studio
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@MikeK Adding it to the main project (which doesn't actually directly depend on it) is an even bigger hack, imo. Then you have to manage it two places ("manage" as in upgrade or remove). With this hack, at least you get a nice compile time error reminding you to remove this hack w...
How does the const constructor actually work?
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Const constructor creates a "canonicalized" instance.
That is, all constant expressions begin canonicalized, and later these "canonicalized" symbols are used to recognize equivalence of these constants.
Canonicalization:
A process for converting data that has more than one possible rep...
Left align two graph edges (ggplot)
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Using cowplot package:
A <- ggplot(CO2, aes(x=Plant)) + geom_bar() +coord_flip()
B <- ggplot(CO2, aes(x=Type)) + geom_bar() +coord_flip()
library(cowplot)
plot_grid(A, B, ncol=1, align="v")
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