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Assigning default values to shell variables with a single command in bash
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Very close to what you posted, actually:
FOO=${VARIABLE:-default} # If variable not set or null, use default.
Or, which will assign default to VARIABLE as well:
FOO=${VARIABLE:=default} # If variable not set or null, set it to...
Combining multiple git repositories
...ackup of your phd directory: I don't want to be held responsible for your losing years of hard work! ;-)
$ cp -r phd phd-backup
Move the content of phd/code to phd/code/code, and fix the history so that it looks like it has always been there (this uses git's filter-branch command):
$ cd phd/code...
How can i use iptables on centos 7? [closed]
I installed CentOS 7 with minimal configuration (os + dev tools). I am trying to open 80 port for httpd service, but something wrong with my iptables service ... what's wrong with it? What am I doing wrong?
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How can I run PowerShell with the .NET 4 runtime?
...PowerShell (the engine) runs fine under .NET 4.0. PowerShell (the console host and the ISE) do not, simply because they were compiled against older versions of .NET. There's a registry setting that will change the .NET framework loaded systemwide, which will in turn allow PowerShell to use .NET 4.0...
What is the difference between exit and return? [duplicate]
...g is in the main() function, as a return from main performs an exit().
In most C implementations, main is a real function called by some startup code that does something like int ret = main(argc, argv); exit(ret);. The C standard guarantees that something equivalent to this happens if main returns,...
SVG fill color transparency / alpha?
Is it possible to set a transparency or alpha level on SVG fill colours?
5 Answers
5
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How to encode a URL in Swift [duplicate]
...erSet())
Use stringByAddingPercentEscapesUsingEncoding: Deprecated in iOS 9 and OS X v10.11
var address = "American Tourister, Abids Road, Bogulkunta, Hyderabad, Andhra Pradesh, India"
var escapedAddress = address.stringByAddingPercentEscapesUsingEncoding(NSUTF8StringEncoding)
let urlpath = NSS...
How to detect Windows 64-bit platform with .NET?
...-bit .NET Framework 2.0 on 64-bit Windows (it would return 32-bit).
As Microsoft's Raymond Chen describes, you have to first check if running in a 64-bit process (I think in .NET you can do so by checking IntPtr.Size), and if you are running in a 32-bit process, you still have to call the Win API fu...
Replacing some characters in a string with another character
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On *BSD (and thus, OSX), sed -E is (basically) equivalent to sed -r on many Linux distros, If you use sed 's/[xyz][xyz]*/_/g' you don't need the option. Of course, this is equivalent to tr -s xyz _ so no real need for sed here.
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Postgres could not connect to server
After I did brew update and brew upgrade, my postgres got some problem. I tried to uninstall postgres and install again, but it didn't work as well.
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