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How to write a bash script that takes optional input arguments?
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You could use the default-value syntax:
somecommand ${1:-foo}
The above will, as described in Bash Reference Manual - 3.5.3 Shell Parameter Expansion [emphasis mine]:
If parameter is unset or null, the expansion of word is substituted. Otherwise, the value of paramet...
Real life example, when to use OUTER / CROSS APPLY in SQL
I have been looking at CROSS / OUTER APPLY with a colleague and we're struggling to find real life examples of where to use them.
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“Content is not allowed in prolog” when parsing perfectly valid XML on GAE
...ing bug for the last 48 hours, so I thought I'd finally throw in the towel and try asking here before I throw my laptop out the window.
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How to upgrade PostgreSQL from version 9.6 to version 10.1 without losing data?
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Assuming you've used home-brew to install and upgrade Postgres, you can perform the following steps.
Stop current Postgres server:
launchctl unload ~/Library/LaunchAgents/homebrew.mxcl.postgresql.plist
Initialize a new 10.1 database:
initdb /usr/local/var/postgre...
Specify sudo password for Ansible
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You can pass variable on the command line via --extra-vars "name=value". Sudo password variable is ansible_sudo_pass. So your command would look like:
ansible-playbook playbook.yml -i inventory.ini --user=username \
--extra-var...
How to change Navigation Bar color in iOS 7?
... you set the translucent property to NO.
Availability
Available in iOS 7.0 and later.
Declared In
UINavigationBar.h
Code
NSArray *ver = [[UIDevice currentDevice].systemVersion componentsSeparatedByString:@"."];
if ([[ver objectAtIndex:0] intValue] >= 7) {
// iOS 7.0 or later
self.navig...
How to do case insensitive string comparison?
... @jpmc26: Yes; msdn.microsoft.com/en-us/library/bb386042.aspx and en.wikipedia.org/wiki/Capital_%E1%BA%9E
– SLaks
May 27 '14 at 23:44
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What does Docker add to lxc-tools (the userspace LXC tools)?
... "lxc" refers to capabilities of the linux kernel (specifically namespaces and control groups) which allow sandboxing processes from one another, and controlling their resource allocations.
On top of this low-level foundation of kernel features, Docker offers a high-level tool with several powerful...
When to use Preorder, Postorder, and Inorder Binary Search Tree Traversal strategies
...ven contemplated using anything but Inorder traversal (while I am aware of and know how easy it is to adapt a program to use pre/post-order traversal).
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Type Checking: typeof, GetType, or is?
...y_a_dog = new Dog();
Foo(probably_a_dog); // this calls Foo<Animal> and returns "Animal"
Foo<Animal>(probably_a_dog); // this is exactly the same as above
Foo<Dog>(probably_a_dog); // !!! This will not compile. The parameter expects a Dog, you cannot pass in an Animal.
Foo(defini...