Use `-C` option of tar:

    tar zxvf &lt;yourfile&gt;.tar.gz -C /usr/src/
    
and then, the content of the tar should be in:

    /usr/src/&lt;yourfile&gt;

    gunzip &lt;filename&gt;
    
then 
    
    tar -xvf &lt;tar-file-name&gt;
     

I am very new to angularJS. I am searching for accessing services from RESTful API, but I didn&#39;t get any idea. How can I do that?

How to access the services from RESTful API in my angularjs page?

Check if year is leap year in javascript

With the usage of wget command line I got a tar.gz file. I downloaded it in the root@raspberrypi. Is there any way to uncompress it in the /usr/src folder?

Uncompress tar.gz file

<p>With the usage of wget command line I got a tar.gz file. I downloaded it in the root@raspberrypi. Is there any way to uncompress it in the /usr/src folder?</p>


In the header of a Bash script, what&#39;s the difference between those two statements:

 1.  `#!/usr/bin/env bash`

 2.  `#!/usr/bin/bash`

When I consulted the `env` [man page](https://linux.die.net/man/1/env), I get this definition:

&lt;!-- language: none --&gt;

     env - run a program in a modified environment

What does it mean?


What is the difference between &quot;#!/usr/bin/env bash&quot; and &quot;#!/usr/bin/bash&quot;?

I am trying to delete empty lines using sed:

    sed &#39;/^$/d&#39;

but I have no luck with it.

For example, I have these lines:

    xxxxxx
    
    
    yyyyyy
    
    
    zzzzzz

and I want it to be like:

    xxxxxx
    yyyyyy
    zzzzzz

What should be the code for this?

Delete empty lines using sed

I want to run a python script in a CENTOS server:

    #!/usr/bin/env python
    import socket
    try:    
    	import thread 
    except ImportError:
    	import _thread as thread #Py3K changed it.
    class Polserv(object):
    	def __init__(self):
    		self.numthreads = 0
    		self.tidcount   = 0
    		self.port       = 843
    		self.sock       = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    		self.sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    		self.sock.bind((&#39;100.100.100.100&#39;, self.port))
    		self.sock.listen(5)
    	def run(self):
    		while True:
    			thread.start_new_thread(self.handle, self.sock.accept()) 
    	def handle(self,conn,addr):
    		self.numthreads += 1
    		self.tidcount   += 1
    		tid=self.tidcount
    		while True:
    			data=conn.recv(2048)
    			if not data:
    				conn.close()
    				self.numthreads-=1
    				break
    			#if &quot;&lt;policy-file-request/&gt;\0&quot; in data:
    			conn.sendall(b&quot;&lt;?xml version=&#39;1.0&#39;?&gt;&lt;cross-domain-policy&gt;&lt;allow-access-from domain=&#39;*&#39; to-ports=&#39;*&#39;/&gt;&lt;/cross-domain-policy&gt;&quot;)
    			conn.close()
    			self.numthreads-=1
    			break
    		#conn.sendall(b&quot;[#%d (%d running)] %s&quot; % (tid,self.numthreads,data) )
    Polserv().run()
Im using `$ python flashpolicyd.py` and it works fine... 
The question is: How to keep this script running even after I close the terminal(console)?



How to make Python script run as service?

I installed [request module][1], and getting the error:

    module.js:340
        throw err;
              ^
    Error: Cannot find module &#39;request&#39;

i&#39;ve read all the posts about this error, and understand that this is because module requests is not globally found, but i&#39;ve already tried the 2 suggestions

&gt; npm install request -g  

should this install it in /usr/loca/bin ? because i don&#39;t see it there. 

and 

&gt; sudo npm link  
&gt;
&gt; /usr/local/lib/node_modules/request -&gt; /Users/soulsonic/dev/sandbox/node_test/request

i restarted terminal after each command, but keep getting the cannot find module  error. 

**update**

there must have been some sort of conflict in my initial directory, because &quot;npm install request&quot; was not adding &quot;request&quot; under node_modules (there 10 others in there) .. 
after switching to a new directory it just worked. 

if i run it with -g switch, i do see it bing installed to /usr/local/lib/node_modules/request. 

it seems that i just need to update my profile so that above path is automatically added. 

  [1]: https://github.com/mikeal/request

node.js: cannot find module &#39;request&#39;

I&#39;m wondering how to declare a 2D array in bash and then initialize to 0.

In C it looks like this:

    int a[4][5] = {0};

And how do I assign a value to an element? As in C:

    a[2][3] = 3;

How to declare 2D array in bash

I am not able to call `rJava` package in `R 3.0`. I got the following message

    Error: package ‘rJava’ was built before R 3.0.0: please re-install it

I am getting error when I tried to re-install `rJava` package. I have provided the output of `R CMD javareconf`
 

    Java interpreter : /usr/bin/java
    Java version     : 1.7.0_21
    Java home path   : /usr/lib/jvm/java-7-openjdk-i386/jre
    Java compiler    : /usr/lib/jvm/java-7-openjdk-i386/jre/../bin/javac
    Java headers gen.: /usr/lib/jvm/java-7-openjdk-i386/jre/../bin/javah
    Java archive tool: /usr/lib/jvm/java-7-openjdk-i386/jre/../bin/jar
    
    trying to compile and link a JNI progam 
    detected JNI cpp flags    : 
    detected JNI linker flags : 
    gcc -std=gnu99 -I/usr/share/R/include -DNDEBUG      -fpic  -O2 -pipe -g  -c conftest.c -o conftest.o
    conftest.c:1:17: fatal error: jni.h: No such file or directory
    compilation terminated.
    make: *** [conftest.o] Error 1
    Unable to compile a JNI program
    
    
    Java library path: 
    JNI cpp flags    : 
    JNI linker flags : 
    Updating Java configuration in /usr/lib/R
    Done.


I am using Ubuntu 13.04. I also tried `apt-get install r-cran-rjava` which is not helping to solve the issue. Regarding jni.h there were some solution [here.][1] But, not sure how can I use the solution here. 

  [1]: https://stackoverflow.com/questions/14529720/how-to-make-jni-h-be-found

Unable to install rJava in R 3.0 in Ubuntu 13.04

I have a `Postgres db 9.1` running on `AWS EC2`, with `ubuntu 12.04`.

I messed a lot with the instance (i.e installed all kinds of postgres X.X before i settled on 9.1).

Now after a month working on that db, I discovered that if I restart my instance `postgres` doesn&#39;t load correctly, its status says &quot;Running clusters&quot;. this will last forever until I


    sudo service postgresql restart

from terminal, and then it works again.

How do I add this line, to ubuntu startup so that each time it loads, it will restart this service, and hopefully solve my problem?

Also any other solution which might solve this.

postgres, ubuntu how to restart service on startup? get stuck on clustering after instance reboot

How do I change the MySQL root password and username in ubuntu server?  Do I need to stop the mysql service before setting any changes? 

I have a phpmyadmin setup as well, will phpmyadmin get updated automatically?

MySQL: How to reset or change the MySQL root password?

I have a software in ubuntu that requires me to run qmake  to generate the Makefile.

However, running qmake gives back this error,

    qmake: could not find a Qt installation of &#39;&#39;

I have installed what I thought to be the required packages using,

    sudo apt-get install qt4-qmake
    sudo apt-get install qt5-qmake

But the error didn&#39;t go away.

Any help on this would be gladly appreciated!

qmake: could not find a Qt installation of &#39;&#39;

I have a file containing the following lines:

      &lt;parameter name=&quot;PortMappingEnabled&quot; access=&quot;readWrite&quot; type=&quot;xsd:boolean&quot;&gt;&lt;/parameter&gt;
      &lt;parameter name=&quot;PortMappingLeaseDuration&quot; access=&quot;readWrite&quot; activeNotify=&quot;canDeny&quot; type=&quot;xsd:unsignedInt&quot;&gt;&lt;/parameter&gt;
      &lt;parameter name=&quot;RemoteHost&quot; access=&quot;readWrite&quot;&gt;&lt;/parameter&gt;
      &lt;parameter name=&quot;ExternalPort&quot; access=&quot;readWrite&quot; type=&quot;xsd:unsignedInt&quot;&gt;&lt;/parameter&gt;
      &lt;parameter name=&quot;ExternalPortEndRange&quot; access=&quot;readWrite&quot; type=&quot;xsd:unsignedInt&quot;&gt;&lt;/parameter&gt;
      &lt;parameter name=&quot;InternalPort&quot; access=&quot;readWrite&quot; type=&quot;xsd:unsignedInt&quot;&gt;&lt;/parameter&gt;
      &lt;parameter name=&quot;PortMappingProtocol&quot; access=&quot;readWrite&quot;&gt;&lt;/parameter&gt;
      &lt;parameter name=&quot;InternalClient&quot; access=&quot;readWrite&quot;&gt;&lt;/parameter&gt;
      &lt;parameter name=&quot;PortMappingDescription&quot; access=&quot;readWrite&quot;&gt;&lt;/parameter&gt;



I want to execute command on this file to extract only the parameter names as displayed in the following output:

    $sedcommand file.txt
    PortMappingEnabled
    PortMappingLeaseDuration
    RemoteHost
    ExternalPort
    ExternalPortEndRange
    InternalPort
    PortMappingProtocol
    InternalClient
    PortMappingDescription

What could be this command?

How to use sed to extract substring

I launched my program in the foreground (a daemon program), and then I killed it with `kill -9`, but I get a zombie remaining and I m not able to kill it with `kill -9`. How to kill a zombie process?

If the zombie is a dead process (already killed), how I remove it from the output of `ps aux`?

    root@OpenWrt:~# anyprogramd &amp;
    root@OpenWrt:~# ps aux | grep anyprogram
     1163 root      2552 S    anyprogramd
     1167 root      2552 S    anyprogramd
     1169 root      2552 S    anyprogramd
     1170 root      2552 S    anyprogramd
    10101 root       944 S    grep anyprogram
    root@OpenWrt:~# pidof anyprogramd
    1170 1169 1167 1163
    root@OpenWrt:~# kill -9 1170 1169 1167 1163
    root@OpenWrt:~# ps aux |grep anyprogram
     1163 root         0 Z    [anyprogramd]
    root@OpenWrt:~# kill -9 1163
    root@OpenWrt:~# ps aux |grep anyprogram
     1163 root         0 Z    [anyprogramd]



How to kill zombie process

I am new to system administration. After installing nginx [via puppet][1] on Ubuntu I get the following output:

    [alert] could not open error log file: open() &quot;/var/log/nginx/error.log&quot; failed (13: Permission denied)
    
    [warn] 1898#0: the &quot;user&quot; directive makes sense only if the master process runs with super-user privileges, ignored in /etc/nginx/nginx.conf:1
    
    [emerg] 1898#0: open() &quot;/var/log/nginx/access.log&quot; failed (13: Permission denied)

How do I get rid of all of these messages?

I don&#39;t want to use command line directly (chown / chmod) and repeat it every time I create a new server. Therefore, I am thinking of what has to be added to the puppet manifest.

What is the best sysadmin practice in this case: to change owner / permissions for /var/log/nginx or to store logs in different location? If chown / chmod is the way to go, which specific permissions would ensure the highest level of security?

I tried this, but it didn&#39;t help:

      file { &#39;/var/log/nginx&#39;:
        ensure  =&gt; directory,
        mode    =&gt; &#39;0755&#39;,
        owner   =&gt; &#39;www-data&#39;,
        group   =&gt; &#39;www-data&#39;,
        recurse =&gt; true
      }

Edited:

    vagrant@precise64:~$ ps aux | grep [n]ginx
    root      1001  0.0  0.1  62908  1388 ?        Ss   08:47   0:00 nginx: master process /usr/sbin/nginx
    www-data  1002  0.0  0.1  63260  1696 ?        S    08:47   0:00 nginx: worker process
    www-data  1003  0.0  0.1  63260  1696 ?        S    08:47   0:00 nginx: worker process
    www-data  1004  0.0  0.1  63260  1696 ?        S    08:47   0:00 nginx: worker process
    www-data  1005  0.0  0.1  63260  1696 ?        S    08:47   0:00 nginx: worker process

  [1]: https://github.com/kasperisager/puppet-nginx


Nginx: Permission denied for nginx on Ubuntu

I&#39;m thinking to install *hylafax+* version 5.5.4 which was release last month on my [Debian][1] PC.

I checked `dpkg -l | grep &quot;hylafax&quot;` and found out that the current version is 5.5.3. Then I checked `apt-cache search hylafax` and saw the packages are available, but I can&#39;t see any version number.

How can I find the version of packages available in the `apt-get`?

  [1]: http://en.wikipedia.org/wiki/Debian

How to check the version before installing a package using apt-get?

I have a **text file containing a specific date and time.** 
I want to be able to **run a script at the time specified in that file.**
How would you achieve that?
Create another script that runs in background (sort of a deamon) and checks every second if the current time is matching the time in the file?
Is there another way?
The machine is a **linux** server , Debian wheezy.
Thanks in advance

How to run a script at a certain time on Linux?

I&#39;m running an instance of Debian on Amazon EC2 with Node.js installed. If I run the code below:

    http = require(&#39;http&#39;);
    
    http.createServer(function (request, response){
      response.writeHead(200, {&#39;Content-Type&#39;:&#39;text/plain&#39;});
      response.end(&#39;Hello World\n&#39;);
    }).listen(80);
    console.log(&quot;Running server at port 80&quot;);

I get the output below which tells me there&#39;s another process listening at port 80:

    Running server at port 80
    
    events.js:72
            throw er; // Unhandled &#39;error&#39; event
                  ^
    Error: listen EACCES
        at errnoException (net.js:901:11)
        at Server._listen2 (net.js:1020:19)
        at listen (net.js:1061:10)
        at Server.listen (net.js:1127:5)
        at Object.&lt;anonymous&gt; (/home/admin/nodetests/nodetest.js:6:4)
        at Module._compile (module.js:456:26)
        at Object.Module._extensions..js (module.js:474:10)
        at Module.load (module.js:356:32)
        at Function.Module._load (module.js:312:12)
        at Function.Module.runMain (module.js:497:10)

Now when I check to see if there&#39;s a process (as root in case anything is hidden) listening on port 80 using: 

    netstat -tupln

I get the below output, which tells me theres nothing listening at port 80: 

    Active Internet connections (only servers)
    Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
    tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      1667/sshd       
    tcp6       0      0 :::22                   :::*                    LISTEN      1667/sshd

I should note that the debian has port 80 open as an inbound rule if that makes a difference. 

My question is: What am I doing wrong? How come I can&#39;t identify the process listening to port 80? Why is it blocked in Debian? What steps should I take to get the code running correctly?   

Content Type	Original Author	Original Content on Stackoverflow
Question	dali1985	View Question on Stackoverflow
Solution 1 - Linux	qingchen	View Answer on Stackoverflow
Solution 2 - Linux	dratewka	View Answer on Stackoverflow
Solution 3 - Linux	Satya	View Answer on Stackoverflow

Uncompress tar.gz file

Linux Problem Overview

Linux Solutions

Solution 1 - Linux

Solution 2 - Linux

Solution 3 - Linux

Check if year is leap year in javascript

How to access the services from RESTful API in my angularjs page?

Attributions