How to make downloads from Linux machine without GUI

Although I have been working about four years with Solaris, I am not able to do many things using only the command line.

One of the things that I had never been done via the command line is downloads on the Internet.

The magic command is wget. Just pass the download link as a parameter for the command.

I tested this command on a CentOS and it worked very well:


]# wget http://www.smartfoxserver.com/products/download.php?d=76
--2010-12-12 13:20:26--  http://www.smartfoxserver.com/products/download.php?d=76
Resolving www.smartfoxserver.com... 62.149.227.100
Connecting to www.smartfoxserver.com|62.149.227.100|:80... connected.
HTTP request sent, awaiting response... 302 Found
Location: ../download/SFSPRO_linux_1.6.6.tar.gz [following]
--2010-12-12 13:20:27--  http://www.smartfoxserver.com/download/SFSPRO_linux_1.6.6.tar.gz
Connecting to www.smartfoxserver.com|62.149.227.100|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 136461484 (130M) [application/x-gzip]
Saving to: `SFSPRO_linux_1.6.6.tar.gz'


100%[===================================================================================================================>] 136,461,484  221K/s   in 9m 2s


2010-12-12 13:29:29 (246 KB/s) - `SFSPRO_linux_1.6.6.tar.gz' saved [136461484/136461484]


I did not need anything advanced, but you can do miracles with wget, for example,download an entire site. See more details in reference [1].

Reference:
[1] http://www.simplehelp.net/2008/12/11/how-to-download-files-from-the-linux-command-line/

How to configure an error page HTTP 404 Page Not Found for Struts 2

I had the simple task of creating a page for the treatment of HTTP 404 Error Page Not Found on a project using Tomcat/Struts2/Spring.

My first idea was to try to solve this issue in struts.xml, but after some research I was directed to try to solve it in web.xml, as it is done in any Java Web project:

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1. <?xml version="1.0" encoding="ISO-8859-1"?>  
2. <web-app xmlns="http://java.sun.com/xml/ns/j2ee"  
3. xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  
4. xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"  
5. version="2.4">  
6.    <display-name>Aplicacao web simples</display-name>  
7.    <welcome-file-list>  
8.      <welcome-file>/bemvindo.jsp</welcome-file>  
9.    </welcome-file-list>  
10.     <error-page>  
11.         <error-code>404</error-code>  
12.         <location>/erro.jsp</location>  
13.     </error-page>  
14. </web-app>

That did not work. When a non existent page was accessed, the following exception was raised and the page was blank:


2010-12-08 14:50:43 Dispatcher [WARN] Could not find action or result
There is no Action mapped for namespace / and action name pan. - [unknown location]
at com.opensymphony.xwork2.DefaultActionProxy.prepare(DefaultActionProxy.java:178)
at org.apache.struts2.impl.StrutsActionProxy.prepare(StrutsActionProxy.java:61)
at org.apache.struts2.impl.StrutsActionProxyFactory.createActionProxy(StrutsActionProxyFactory.java:39)
at com.opensymphony.xwork2.DefaultActionProxyFactory.createActionProxy(DefaultActionProxyFactory.java:47)
at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:478)
at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)
at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:91)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.springframework.orm.jpa.support.OpenEntityManagerInViewFilter.doFilterInternal(OpenEntityManagerInViewFilter.java:112)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:849)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:454)
at java.lang.Thread.run(Thread.java:619)


After some more research, I was properly directed to the solution, and it really was in struts.xml. No configuration is necessary in web.xml. [1]

You just have to set a default action. So, when struts receives a request that doesn't match any action, the request will be sent to your custom error page. The struts.xml looks like this:


    <default-action-ref name="pageNotFound" />

    <action name="pageNotFound">

        <result>/pageNotFound.jsp</result>

    </action>

Links:
[1] http://struts.apache.org/2.0.14/docs/action-configuration.html
[2] http://wiki.metawerx.net/wiki/Web.xml.ErrorCode
[3] http://www.coderanch.com/t/428310/Struts/Interceptor-messes-up-action-class
[4] http://www.mkyong.com/struts2/there-is-no-action-mapped-for-namespace-and-action-name-youractionname/