There is an implementation of gzip that is multithreaded, [pigz][1]. Since it is compressing one file on multiple threads, it should be able to read from disk more efficiently, compared to compressing multiple files at once.


  [1]: http://www.zlib.net/pigz/

If you are on Linux, you can use GNU&#39;s xargs to launch as many processes as you have cores.

    CORES=$(grep -c &#39;^processor&#39; /proc/cpuinfo)
    find /source -type f -print0 | xargs -0 -n 1 -P $CORES gzip -9

 - find -print0 / xargs -0 protects you from whitespace in filenames
 - xargs -n 1 means one gzip process per file
 - xargs -P specifies the number of jobs
 - gzip -9 means maximum compression



You might want to consider checking [GNU parallel][1]. I also found this [video on youtube][2] which seems to do what you are looking for.


  [1]: http://www.gnu.org/software/parallel/
  [2]: http://www.youtube.com/watch?v=OpaiGYxkSuQ

I&#39;m fairly new to Git, and still getting the hang of it. I just recently started working with branches and am running into some questions.

I have two development systems, an Ubuntu desktop and an MacBookPro. I did a bunch of work in a new `organizations` branch on the Ubuntu system and performed commits and pushed to my remote repo. At this point, I had these branches:

    tauren@ubuntu:/projects$ git branch
      accounting
      master
    * organizations

    tauren@ubuntu:/projects$ git branch -r
      origin/accounting
      origin/master
      origin/organizations
      origin/superstar

Then I switched to the MBP to pull the new branch:

    tauren@osx:/projects$ git branch
      accounting
    * master

    tauren@osx:/projects$ git branch -r
      origin/HEAD -&gt; origin/master
      origin/accounting
      origin/master
      origin/superstar

    tauren@osx:/projects$ git pull
       2e20a14..ef35730  accounting -&gt; origin/accounting
       271a1a5..7e947ab  master     -&gt; origin/master
     * [new branch]      organizations -&gt; origin/organizations

    tauren@osx:/projects$ git branch
    * accounting
      master

    tauren@osx:/projects$ git branch -r
      origin/HEAD -&gt; origin/master
      origin/accounting
      origin/master
      origin/organizations
      origin/superstar

So my questions are these:

1. Why does the MBP have a branch `origin/HEAD -&gt; origin/master`, but the Ubuntu system doesn&#39;t? What is that branch?
2. Does `git pull` automatically pull all new remote branches? I thought I had to tell it the name of new branches to pull. As you can see, it pulled the remote `organizations` branch on the commmand `git pull`.






Git branch named origin/HEAD -&gt; origin/master

I have a column in one of my tables which has been assigned an index. It is preventing me from having two of the same ID number. 

I am assuming the reason it is not letting me have two entries of the same ID is because it has been set to be Unique.

I am wondering how do I remove this rule so that I can insert the same ID number several times.

Cheers

phpMyAdmin Removing an index

I have a set of servers filled each with a bunch of files that can be gzipped.  The servers all have different numbers of cores.  How can I write a bash script to launch a gzip for each core and make sure the gzips are not zipping the same file?

Gzip with all cores

<p>I have a set of servers filled each with a bunch of files that can be gzipped.  The servers all have different numbers of cores.  How can I write a bash script to launch a gzip for each core and make sure the gzips are not zipping the same file?</p>


I have a large __file A__ (consisting of emails), one line for each mail. I also have another __file B__ that contains another set of mails.

Which command would I use to remove all the addresses that appear in file B from the file A.

So, if file A contained:

    A
    B
    C

and file B contained:

    B    
    D
    E

Then file A should be left with:

    A
    C

Now I know this is a question that might have been asked more often, but I only found [one command online](http://www.thelinuxblog.com/remove-lines-that-are-in-another-file/) that gave me an error with a bad delimiter.

Any help would be much appreciated! Somebody will surely come up with a clever one-liner, but I&#39;m not the shell expert.

How to remove the lines which appear on file B from another file A?

From what I&#39;ve read it&#39;s used to fix bugs in the CPU without modifying the BIOS.
From my basic knowledge of Assembly I know that assembly instructions are split into microcodes internally by the CPU and executed accordingly. But intel somehow gives access to make some updates while the system is up and running.

Anyone has more info on them? Is there any documentation regarding what can it be done with microcodes and how can they be used?

------
EDIT: 
I&#39;ve read the wikipedia article: didn&#39;t figure out how can I write some on my own, and what uses it would have.

What is Intel microcode?

GNU Screen seems to freeze. Unable to enter user input.  

I was using GNU screen and when I pressed the screen it became unresponsive. I can execute all the GNU screen commands, but can&#39;t enter user input. I don&#39;t want to kill this screen as I have important work and I don&#39;t want to lose it.

The GNU screen is unresponsive, seems blocked

The following grep expression successfully lists all the .exe and .html files in the current directory and sub directories.  

    ls -R |grep -E .*[\.exe]$\|.*[\.html]$  

How do I invert this result to list those that aren&#39;t a .html or .exe instead. (That is, `!=`.)


How to invert a grep expression

I want to find the non-readable files in my directory (eg the files with g-r).  So I tried this:

`find . -perm -g-r`

It shows me all of the files??  So I tried this:

`find . -perm -g+r`

And it showed me only the readable files.  It appears that `-perm -g-r` matches all files.  I&#39;m using CentOS 5.5.  Am I doing something wrong?  It doesn&#39;t look like `-perm -g-r` does anything useful.

Using `find -perm` to find when a permission is not set

I&#39;m building a Shell Script that has a `if` function like this one:

    if jarsigner -verbose -keystore $keyst -keystore $pass $jar_file $kalias
    then
        echo $jar_file signed sucessfully
    else
        echo ERROR: Failed to sign $jar_file. Please recheck the variables
    fi
    
    ...

I want the execution of the script to finish after displaying the error message. How I can do this?

Exit a Script On Error

It&#39;s frustrating when I do something like `man bindkey` and i get:

&lt;pre&gt;
BUILTIN(1)                BSD General Commands Manual               BUILTIN(1)

NAME
     builtin, !, %, ., :, @, {, }, alias, alloc, bg, bind, bindkey, break, breaksw, builtins, case, cd, chdir, command,
     complete, continue, default, dirs, do, done, echo, echotc, elif, else, end, endif, endsw, esac, eval, exec, exit,
     export, false, fc, fg, filetest, fi, for, foreach, getopts, glob, goto, hash, hashstat, history, hup, if, jobid,
     jobs, kill, limit, local, log, login, logout, ls-F, nice, nohup, notify, onintr, popd, printenv, pushd, pwd, read,
     readonly, rehash, repeat, return, sched, set, setenv, settc, setty, setvar, shift, source, stop, suspend, switch,
     telltc, test, then, time, times, trap, true, type, ulimit, umask, unalias, uncomplete, unhash, unlimit, unset,
     unsetenv, until, wait, where, which, while -- shell built-in commands

SYNOPSIS
     builtin [-options] [args ...]

DESCRIPTION
     Shell builtin commands are commands that can be executed within the running shell&#39;s process.  Note that, in the
&lt;/pre&gt;

Is there an easy way to access the documentation for such commands?


How can I read documentation about built in zsh commands?

I am writing a bash shell script to display if a process is running or not.

So far, I got this:

    printf &quot;%-50s %s\n&quot; $PROC_NAME [UP]

The code gives me this output:

    JBoss                                              [DOWN]
    
    GlassFish                                          [UP]
    
    verylongprocessname                                [UP]

I want to pad the gap between the two fields with a &#39;-&#39; or &#39;*&#39; to make it more readable. How do I do that without disturbing the alignment of the fields?

The output I want is:

    JBoss -------------------------------------------  [DOWN]
    
    GlassFish ---------------------------------------  [UP]
    
    verylongprocessname -----------------------------  [UP]



Padding characters in printf

I am writing a bash script that needs to get the header (first 10 bytes) of a file and then in another section get everything except the first 10 bytes.  These are binary files and will likely have `\0`&#39;s and `\n`&#39;s throughout the first 10 bytes.  It seems like most utilities work with ASCII files.  What is a good way to achieve this task?

How to get only the first ten bytes of a binary file

Is there any way to check if InputStream has been gzipped?
Here&#39;s the code:

    public static InputStream decompressStream(InputStream input) {
		try {
			GZIPInputStream gs = new GZIPInputStream(input);
			return gs;
		} catch (IOException e) {
			logger.info(&quot;Input stream not in the GZIP format, using standard format&quot;);
			return input;
		}
	}

I tried this way but it doesn&#39;t work as expected - values read from the stream are invalid.
EDIT:
Added the method I use to compress data: 

    public static byte[] compress(byte[] content) {
		ByteArrayOutputStream baos = new ByteArrayOutputStream();
		try {
			GZIPOutputStream gs = new GZIPOutputStream(baos);
			gs.write(content);
			gs.close();
		} catch (IOException e) {
			logger.error(&quot;Fatal error occured while compressing data&quot;);
			throw new RuntimeException(e);
		}
		double ratio = (1.0f * content.length / baos.size());
		if (ratio &gt; 1) {
			logger.info(&quot;Compression ratio equals &quot; + ratio);
			return baos.toByteArray();
		}
		logger.info(&quot;Compression not needed&quot;);
		return content;

	}

How to check if InputStream is Gzipped?

I&#39;ve been looking for ways of making my site load faster and one way that I&#39;d like to explore is making greater use of Cloudfront.

Because Cloudfront was originally not designed as a custom-origin CDN and because it didn&#39;t support gzipping, I have so far been using it to host all my images, which are referenced by their Cloudfront cname in my site code, and optimized with far-futures headers.

CSS and javascript files, on the other hand, are hosted on my own server, because until now I was under the impression that they couldn&#39;t be served gzipped from Cloudfront, and that the gain from gzipping (about 75 per cent) outweighs that from using a CDN (about 50 per cent): Amazon S3 (and thus Cloudfront) did not support serving gzipped content in a standard manner by using the HTTP Accept-Encoding header that is sent by browsers to indicate their support for gzip compression, and so they were not able to Gzip and serve components on the fly.

Thus I was under the impression, until now, that one had to choose between two alternatives:

1. move all assets to the Amazon CloudFront and forget about GZipping;

2. keep components self-hosted and configure our server to detect incoming requests and perform on-the-fly GZipping as appropriate, which is what I chose to do so far.

There _were_ workarounds to solve this issue, but essentially these **didn&#39;t work**. [[link](http://www.alfajango.com/blog/how-to-combine-gzip-plus-cdn-for-fastest-page-loads/)].

Now, it seems Amazon Cloudfront supports custom origin, and that **it is now possible to use the standard HTTP Accept-Encoding method for serving gzipped content if you are using a Custom Origin**  [[link](http://www.nomitor.com/blog/2010/11/10/gzip-support-for-amazon-web-services-cloudfront/)].

I haven&#39;t so far been able to implement the new feature on my server.  The blog post I linked to above, which is the only one I found detailing the change, seems to imply that you can only enable gzipping (bar workarounds, which I don&#39;t want to use), if you opt for custom origin, which I&#39;d rather not: I find it simpler to host the coresponding fileds on my Cloudfront server, and link to them from there. Despite carefully reading the documentation, I don&#39;t know:

*  whether the new feature means the files should be hosted on my own domain server _via_ custom origin, and if so, what code setup will achieve this;

* how to configure the css and javascript headers to make sure they are served gzipped from Cloudfront.


Serving gzipped CSS and JavaScript from Amazon CloudFront via S3

&lt;!-- language: lang-python --&gt;

    plaintext = input(&quot;Please enter the text you want to compress&quot;)
    filename = input(&quot;Please enter the desired filename&quot;)
    with gzip.open(filename + &quot;.gz&quot;, &quot;wb&quot;) as outfile:
        outfile.write(plaintext) 

The above python code is giving me following error:

&lt;!-- language: lang-none --&gt;

    Traceback (most recent call last):
      File &quot;C:/Users/Ankur Gupta/Desktop/Python_works/gzip_work1.py&quot;, line 33, in &lt;module&gt;
        compress_string()
      File &quot;C:/Users/Ankur Gupta/Desktop/Python_works/gzip_work1.py&quot;, line 15, in compress_string
        outfile.write(plaintext)
      File &quot;C:\Python32\lib\gzip.py&quot;, line 312, in write
        self.crc = zlib.crc32(data, self.crc) &amp; 0xffffffff
    TypeError: &#39;str&#39; does not support the buffer interface


TypeError: &#39;str&#39; does not support the buffer interface

I have used `?unzip` in the past to get at contents of a zipped file using R.  This time around, I am having a hard time extracting the files from a .gz file which can be found [here][1].

I have tried `?gzfile` and `?gzcon` but have not been able to get it to work.  Any help you can provide will be greatly appreciated.


  [1]: http://sourceforge.net/projects/chadwick/files/chadwick-0.5/0.5.3/chadwick-0.5.3.tar.gz/download

Decompress gz file using R

I would like to gzip compress a file on my server using PHP.  Does anyone have an example that would input a file and output a compressed file?

Content Type	Original Author	Original Content on Stackoverflow
Question	User1	View Question on Stackoverflow
Solution 1 - Linux	David Yaw	View Answer on Stackoverflow
Solution 2 - Linux	Demosthenex	View Answer on Stackoverflow
Solution 3 - Linux	Gangadhar	View Answer on Stackoverflow

Gzip with all cores

Linux Problem Overview

Linux Solutions

Solution 1 - Linux

Solution 2 - Linux

Solution 3 - Linux

phpMyAdmin Removing an index

Git branch named origin/HEAD -> origin/master

Attributions