There isn&#39;t any semantic difference. The backtick syntax is the older and less powerful version. See [man bash][1], section &quot;Command Substitution&quot;.

If your shell supports the `$()` syntax, prefer it because it can be nested.

  [1]: https://linux.die.net/man/1/bash


I am currently working on an application that requires high-performance conversion of an unpadded byte array to either a PNG or JPEG. The image format doesn&#39;t matter, just as long as it&#39;s fast.

I have tried the .NET libraries and the performance is very bad. Can anyone recommend a good freeware library for this?

EDIT: the byte[] is an 8bit grayscale bitmap

Converting a byte array to PNG/JPG

I need to know: What is the time complexity of HashMap.containsKey() in java?


What is the time complexity of HashMap.containsKey() in java?

I see two different forms in Bash scripts which seem to do the same:

```lang-none
`some command`
```

and

```lang-none
$(some command)
```

What is the difference between the two, and when should I use each one of them?




What is the difference between backticks and $() in a Bash script?

I see two different forms in Bash scripts which seem to do the same:
<pre><code class="hljs language-bash">`some command`
</code></pre>
and
<pre><code class="hljs language-shell">$(some command)
</code></pre>
What is the difference between the two, and when should I use each one of them?

I have a scanning server I wrote in cgi/bash and want to be able to convert a bunch of images (all in one folder) to a pdf from the command line. How can that be done?

How can I convert a series of images to a PDF from the command line on linux?

I&#39;m on OSX and I need to put something like this, `alias blah=&quot;/usr/bin/blah&quot;` in a config file but I don&#39;t know where the config file is. 


How do I create a Bash alias?

I have made [Bash][1] scripts before and they all ran fine without `#!/bin/bash` at the beginning.

What&#39;s the point of putting it in? Would things be any different?

Also, how do you pronounce `#`? I know that `!` is pronounced as &quot;bang.&quot;

How is `#!` pronounced?

  [1]: http://en.wikipedia.org/wiki/Bash_%28Unix_shell%29


Why do you need to put #!/bin/bash at the beginning of a script file?

I just want to check if one parameter was supplied in my bash script or not. 

I found [this][1], but all the solutions seem to be unnecessarily complicated.

What&#39;s a simple solution to this simple problem that would make sense to a beginner?


  [1]: https://stackoverflow.com/questions/699576/validating-parameters-to-a-bash-script

How to check that a parameter was supplied to a bash script

I&#39;ve looked around for an answer to this one but couldn&#39;t find one.

I have written a simple script that does initial server settings and I&#39;d like it to remove/unlink itself from the root directory on completion. I&#39;ve tried a number of solutions i googled ( for example /bin/rm $test.sh)   but the script always seems to remain in place. Is this possible? Below is my script so far.

    #! /bin/bash
    cd /root/
    wget -r -nH -np --cut-dirs=1 http://myhost.com/install/scripts/
    rm -f index.html* *.gif */index.html* */*.gif robots.txt
    ls -al /root/
    
    if [ -d /usr/local/psa ]
    	then
            echo plesk &gt; /root/bin/INST_SERVER_TYPE.txt
    	chmod 775 /root/bin/*
    	/root/bin/setting_server_ve.sh
    	rm -rf /root/etc | rm -rf /root/bin | rm -rf /root/log | rm -rf /root/old
    	sed -i &quot;75s/false/true/&quot; /etc/permissions/jail.conf
            exit 1;
    elif [ -d /var/webmin ]
    	then
    	echo webmin &gt; /root/bin/INST_SERVER_TYPE.txt
    	chmod 775 /root/bin/*
    	/root/bin/setting_server_ve.sh
    	rm -rf /root/etc | rm -rf /root/bin | rm -rf /root/log | rm -rf /root/old
    	sed -i &quot;67s/false/true/&quot; /etc/permissions/jail.conf
            break
    	exit 1;
    else
    	echo no-gui &gt; /root/bin/INST_SERVER_TYPE.txt
    	chmod 775 /root/bin/*
    	/root/bin/setting_server_ve.sh
    	rm -rf /root/etc | rm -rf /root/bin | rm -rf /root/log | rm -rf /root/old
    	sed -i &quot;67s/false/true/&quot; /etc/permissions/jail.conf
            break
    	exit 1;
    fi	



self-deleting shell script

There are two ways to capture the output of command line in `bash`:

 1. Legacy Bourne shell backticks ``` `` ```:

        var=`command`

 2. `$()` syntax (which as far as I know is Bash specific, or at least not supported by non-POSIX old shells like original Bourne)

        var=$(command)

Is there any benefit to using the second syntax compared to backticks? Or are the two fully 100% equivalent?


What is the benefit of using $() instead of backticks in shell scripts?

In JavaScript, a backtick&lt;sup&gt;&amp;dagger;&lt;/sup&gt; seems to work the same as a single quote. For instance, I can use a backtick to define a string like this:

    var s = `abc`;

Is there a way in which the behavior of the backtick actually differs from that of a single quote?

---
&lt;sup&gt;&amp;dagger; Note that among programmers, &quot;backtick&quot; is one name for what is more generally called the [grave accent][1]. Programmers also sometimes use the [alternate names][2] &quot;backquote&quot; and &quot;backgrave&quot;. Also, [on Stack Overflow][3] and elsewhere, other common spellings for &quot;backtick&quot; are &quot;back-tick&quot; and &quot;back tick&quot;.&lt;/sup&gt;

  [1]: https://en.wikipedia.org/wiki/Grave_accent
  [2]: https://en.wikipedia.org/wiki/Grave_accent#Use_in_programming
  [3]: https://stackoverflow.com/search?q=back-tick



Usage of the backtick character (`) in JavaScript

What are the backticks used for in the snippet below? 

Why add them around the `fun is(amount:Int ):Boolean { ... }`?

    verifier.`is`(amount)

Content Type	Original Author	Original Content on Stackoverflow
Question	Misha Moroshko	View Question on Stackoverflow
Solution 1 - Bash	thiton	View Answer on Stackoverflow

What is the difference between backticks and $() in a Bash script?

Bash Problem Overview

Bash Solutions

Solution 1 - Bash

What is the time complexity of HashMap.containsKey() in java?

Converting a byte array to PNG/JPG

Attributions