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What does “export” do in shell programming? [duplicate]
...ssignment visible to subprocesses.
jcomeau@intrepid:~/rentacoder/bin2txt$ foo=bar
jcomeau@intrepid:~/rentacoder/bin2txt$ bash -c 'echo $foo'
jcomeau@intrepid:~/rentacoder/bin2txt$ export foo
jcomeau@intrepid:~/rentacoder/bin2txt$ bash -c 'echo $foo'
bar
...
Setting up foreign keys in phpMyAdmin?
I'm setting up a database using phpMyAdmin. I have two tables ( foo and bar ), indexed on their primary keys . I am trying to create a relational table ( foo_bar ) between them, using their primary keys as foreign keys.
...
Unable to install Maven on Windows: “JAVA_HOME is set to an invalid directory”
I followed the Maven tutorial to the letter but I still can't get Maven installed on Windows.
16 Answers
...
Is the order of elements in a JSON list preserved?
...e the order.
The following script will output "One", "Two", "Three":
var foo={"3":"Three", "1":"One", "2":"Two"};
for(bar in foo) {
alert(foo[bar]);
}
Whereas the following script will output "Three", "One", "Two":
var foo={"@3":"Three", "@1":"One", "@2":"Two"};
for(bar in foo) {
alert(...
Will the Garbage Collector call IDisposable.Dispose for me?
...r this:
class Program
{
static void Main(string[] args)
{
Foo foo = new Foo();
foo = null;
Console.WriteLine("foo is null");
GC.Collect();
Console.WriteLine("GC Called");
Console.ReadLine();
}
}
class Foo : IDisposable
{
public void D...
Replace a value if null or undefined in JavaScript
... // false
// Equivalent to
a = a ?? true
Object/Array Examples
let x = ["foo"]
let y = { foo: "fizz" }
x[0] ??= "bar" // "foo"
x[1] ??= "bar" // "bar"
y.foo ??= "buzz" // "fizz"
y.bar ??= "buzz" // "buzz"
x // Array [ "foo", "bar" ]
y // Object { foo: "fizz", bar: "buzz" }
Functional Exa...
JavaScript: How to pass object by value?
...ject.
var o = {};
(function(x){
var obj = Object.create( x );
obj.foo = 'foo';
obj.bar = 'bar';
})(o);
alert( o.foo ); // undefined
So any properties you add to obj will be not be added to o. Any properties added to obj with the same property name as a property in o will shadow the o...
Is it better to use std::memcpy() or std::copy() in terms to performance?
... for a simple std::copy of a POD type.
#include <algorithm>
struct foo
{
int x, y;
};
void bar(foo* a, foo* b, size_t n)
{
std::copy(a, a + n, b);
}
Here's the disassembly (with only -O optimisation), showing the call to memmove:
bar(foo*, foo*, unsigned long):
salq $3, %r...
How do I save a String to a text file using Java?
In Java, I have text from a text field in a String variable called "text".
24 Answers
...
How to delete a file or folder?
...ling.
EXAMPLE for os.path.isfile
#!/usr/bin/python
import os
myfile="/tmp/foo.txt"
## If file exists, delete it ##
if os.path.isfile(myfile):
os.remove(myfile)
else: ## Show an error ##
print("Error: %s file not found" % myfile)
###Exception Handling
#!/usr/bin/python
import os
## Get...