You must use `==` in numeric comparisons in `(( ... ))`:

    $ if (( 3 == 3 )); then echo &quot;yes&quot;; fi
    yes
    $ if (( 3 = 3 ));  then echo &quot;yes&quot;; fi
    bash: ((: 3 = 3 : attempted assignment to non-variable (error token is &quot;= 3 &quot;)

You may use either for string comparisons in `[[ ... ]]` or `[ ... ]` or `test`:

    $ if [[ 3 == 3 ]]; then echo &quot;yes&quot;; fi
    yes
    $ if [[ 3 = 3 ]]; then echo &quot;yes&quot;; fi
    yes
    $ if [ 3 == 3 ]; then echo &quot;yes&quot;; fi
    yes
    $ if [ 3 = 3 ]; then echo &quot;yes&quot;; fi
    yes
    $ if test 3 == 3; then echo &quot;yes&quot;; fi
    yes
    $ if test 3 = 3; then echo &quot;yes&quot;; fi
    yes

&quot;String comparisons?&quot;, you say?

    $ if [[ 10 &lt; 2 ]]; then echo &quot;yes&quot;; fi    # string comparison
    yes
    $ if (( 10 &lt; 2 )); then echo &quot;yes&quot;; else echo &quot;no&quot;; fi    # numeric comparison
    no
    $ if [[ 10 -lt 2 ]]; then echo &quot;yes&quot;; else echo &quot;no&quot;; fi  # numeric comparison
    no


There&#39;s a subtle difference with regards to POSIX. Excerpt from the [Bash reference](http://www.gnu.org/software/bash/manual/html_node/Bash-Conditional-Expressions.html):

 &gt; `string1 == string2`  
 &gt; True if the strings are equal.  `=` may be used in place of `==` for strict POSIX compliance.





Is there an RFC, official standard, or template for creating a User Agent string? The iphone&#39;s user-agent string seems strange...

&gt;&gt;Mozilla/5.0 (iPhone; U; __CPU iPhone OS 3_1_2 like Mac OS X__; en-us) AppleWebKit/528.18 (__KHTML, like Gecko__) Version/4.0 Mobile/7D11 Safari/528.16
 

What is the standard format for a browser&#39;s User-Agent string?

I want to take an anonymous object as argument to a method, and then iterate over its properties to add each property/value to a a dynamic `ExpandoObject`.  

So what I need is to go from 

    new { Prop1 = &quot;first value&quot;, Prop2 = SomeObjectInstance, Prop3 = 1234 }

to knowing names and values of each property, and being able to add them to the `ExpandoObject`.

How do I accomplish this?

Side note: This will be done in many of my unit tests (I&#39;m using it to refactor away a lot of junk in the setup), so performance is to some extent relevant. I don&#39;t know enough about reflection to say for sure, but from what I&#39;ve understood it&#39;s pretty performance heavy, so if it&#39;s possible I&#39;d rather avoid it...

**Follow-up question:**
As I said, I&#39;m taking this anonymous object as an argument to a method. What datatype should I use in the method&#39;s signature? Will all properties be available if I use `object`?

How do I iterate over the properties of an anonymous object in C#?

It seems that these two operators are pretty much the same - is there a difference? When should I use `=` and when `==`?

What is the difference between operator &quot;=&quot; and &quot;==&quot; in Bash?

<p>It seems that these two operators are pretty much the same - is there a difference? When should I use <code>=</code> and when <code>==</code>?</p>


Given the following command,

    echo &quot;1: &quot; | awk &#39;/1/ -F &quot;:&quot; {print $1}&#39;

why does AWK output:

    1:

?




How can I use &quot;:&quot; as an AWK field separator?

    sed &quot;s/$.*$/\t\1/&quot; $filename &gt; $sedTmpFile &amp;&amp; mv $sedTmpFile $filename

I am expecting this `sed` script to insert a `tab` in front of every line in `$filename` however it is not. For some reason it is inserting a `t` instead.

Why is sed not recognizing \t as a tab?

How can I programmatically (i.e., not using [`vi`][1]) convert DOS/Windows newlines to Unix?

The `dos2unix` and `unix2dos` commands are not available on certain systems. How can I emulate these with commands like `sed`, `awk`, and `tr`?

  [1]: https://en.wikipedia.org/wiki/Vi





How to convert DOS/Windows newline (CRLF) to Unix newline (LF) in a Bash script

How can I find out where an alias is defined on my system?  I am referring to the kind of alias that is used within a Terminal session launched from Mac OS X (10.6.3).

For example, if I enter the `alias` command with no parameters at a Terminal command prompt, I get a list of aliases that I have set, for example:

    alias mysql=&#39;/usr/local/mysql/bin/mysql&#39;

However, I have searched all over my system using Spotlight and `mdfind` in various startup files and so far can not find where this alias has been defined. ( I did it a long time ago and didn&#39;t write down where I assigned the alias).

How to find out where alias (in the bash sense) is defined when running Terminal in Mac OS X

How do I create an **unmodified** hex dump of a binary file in Linux using bash? The `od` and `hexdump` commands both insert spaces in the dump and this is not ideal.

Is there a way to simply write a long string with all the hex characters, minus spaces or newlines in the output?

How to create a hex dump of file containing only the hex characters without spaces in bash?

I know the [modulus][1] (%) operator calculates the remainder of a division. How can I identify a situation where I would need to use the modulus operator?

I know I can use the modulus operator to see whether a number is even or odd and prime or composite, but that&#39;s about it. I don&#39;t often think in terms of remainders. I&#39;m sure the modulus operator is useful, and I would like to learn to take advantage of it. 

I just have problems identifying where the modulus operator is applicable. In various programming situations, it is difficult for me to see a problem and realize &quot;Hey! The remainder of division would work here!&quot;.

  [1]: http://en.wikipedia.org/wiki/Modulo_operation


Recognizing when to use the modulus operator

I have a codebase where developers decided to use `AND` and `OR` instead of `&amp;&amp;` and `||`.

I know that there is a difference in operators&#39; precedence (`&amp;&amp;` goes before `and`), but with the given framework ([PrestaShop][1] to be precise) it is clearly not a reason.

Which version are you using? Is `and` more readable than `&amp;&amp;`? Or is there no difference?

  [1]: https://en.wikipedia.org/wiki/PrestaShop


&#39;AND&#39; vs &#39;&amp;&amp;&#39; as operator

What is the difference between `&gt;&gt;&gt;` and `&gt;&gt;` operators in Java?

Difference between &gt;&gt;&gt; and &gt;&gt;

null coalescing translates roughly to `return x, unless it is null, in which case return y`

I often need `return null if x is null, otherwise return x.y`

I can use `return x == null ? null : x.y;`

Not bad, but that `null` in the middle always bothers me -- it seems superfluous. I&#39;d prefer something like `return x :: x.y;`, where what follows the `::` is evaluated only if what precedes it is not `null`.

I see this as *almost* an opposite to null coalescence, kind of mixed in with a terse, inline null-check, but I&#39;m [*almost*] certain that there is no such operator in C#.

### Are there other languages that have such an operator? If so, what is it called? ###


*(I know that I can write a method for it in C#; I use `return NullOrValue.of(x, () =&gt; x.y);`, but if you have anything better, I&#39;d like to see that too.)*

Is there an &quot;opposite&quot; to the null coalescing operator? (…in any language?)

What is this double-colon `::`? E.g. `Foo::Bar`.

I found a [definition][1]: 

&gt; The `::` is a unary operator that allows: constants, instance methods and class methods defined within a class or module, to be accessed from anywhere outside the class or module.

What good is scope (private, protected) if you can just use `::` to expose anything?


  [1]: http://marcricblog.blogspot.com/2007/11/ruby-double-colon.html

Content Type	Original Author	Original Content on Stackoverflow
Question	Debugger	View Question on Stackoverflow
Solution 1 - Bash	Dennis Williamson	View Answer on Stackoverflow
Solution 2 - Bash	ghostdog74	View Answer on Stackoverflow

What is the difference between operator "=" and "==" in Bash?

Bash Problem Overview

Bash Solutions

Solution 1 - Bash

Solution 2 - Bash

How do I iterate over the properties of an anonymous object in C#?

What is the standard format for a browser's User-Agent string?

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