Recent Notes
Displaying keyword search results 1 - 10
Created by voodoo on March 24, 2013 13:44:47
Last update: March 29, 2013 13:08:31
Use getpwnam group of functions. Example code:
#include <sys/types.h>
#include <pwd.h>
#inc...
For gid, use getgrnam
Created by magnum on November 03, 2012 08:57:35
Last update: November 03, 2012 08:57:35
Code snippet to check user name and password in C in Linux
#include <sys/types.h>
#include <pwd.h>
#inc...
Created by voodoo on September 25, 2012 19:33:02
Last update: September 25, 2012 19:33:02
This a step-by-step example of how to create the files for GNU automake. Put the C source file in directory src ( cat src/hello.c ):
#include <config.h> #include <stdio.h> ... Run autoscan to generate configure.scan . Rename configure.scan : mv configure.scan configure.ac Edit autoscan.ac . Update this line: AC_INIT([FULL-PACKAGE-NAME], [VERSION] , [BUG-REP... Add this line after AC_INIT : AM_INIT_AUTOMAKE([foreign -Wall -Werror]) Add this line before AC_OUTPUT : AC_CONFIG_FILES([Makefile src/Makefile]) Create file Makefile.am ( cat Makefile.am ): SUBDIRS = src Create file src/Makefile.am ( cat src/Makefile.am ): bin_PROGRAMS = hello hello_SOURCES = hello.c Run these commands: $ aclocal $ autoheader $ automake --add-miss... The file configure is generated after autoconf is run. Build with: $ ./configure $ make Create tarball for distribution with: $ make dist...
Created by magnum on September 11, 2012 12:38:00
Last update: September 11, 2012 12:38:00
From bind man page:
SYNOPSIS
#include <sys/types.h>
...
The bind call assigns an address and a port to a socket. That's it. There's no mention of client or server, so it can be used on a client socket or a server socket. But it's necessary for a server socket, otherwise clients do not know how to contact the server.
For a client socket, the call is optional. When a client connects to a server or sends a message for the first time, a dynamic port is assigned to the client if there's no port assigned to it. If a port is bind beforehand, there's no dynamic assignment.
Test code:
int print_sock_info(int sockfd) {
struct so...
Prints:
Local addr: 0.0.0.0, port: 0
Local addr: 0.0.0....
Created by Fang on April 16, 2012 13:18:40
Last update: April 16, 2012 13:18:40
Simply call pageContext.setAttribute() to export a variable from within a JSP custom tag:
public class MyCustomVarTag extends TagSupport {
...
The availability of the exported variable can be limited in the TLD:
<tag>
<name>setVar</name>
<tag-class...
The availability scopes are:
Value Availability
NESTED Between the start tag and the end tag.
AT_BEGIN From the start tag until the scope of any enclosing tag. If there’s no enclosing tag, then to the end of the page.
AT_END After the end tag until the scope of any enclosing tag. If there’s no enclosing tag, then to the end of the page.
Created by Fang on April 16, 2012 12:58:35
Last update: April 16, 2012 12:58:35
To implement a JSP custom tag with dynamic attributes (for example, to pass-thru arbitrary attributes not handled by the JSP tag):
Set the dynamic-attributes element to true in the TLD:
<tag>
<name>mark</name>
<tag-class>c...
The tag handler must implement javax.servlet.jsp.tagext.DynamicAttributes :
package com.example.jsp;
import java.io.*;
...
Created by magnum on January 30, 2012 18:13:52
Last update: January 30, 2012 18:13:52
There are two ways you cat get the name of a host from its ip address: getnameinfo and gethostbyaddr . The former is IPV6 compatible.
Using getnameinfo :
#include <sys/types.h>
#include <sys/socket.h>
...
Using gethostbyaddr :
#include <sys/types.h>
#include <sys/socket.h>
...
Created by Fang on January 28, 2012 13:24:09
Last update: January 28, 2012 13:31:22
This is a simple JSP custom tags library with tag body. Just like the JSF counterpart , it splits a string and repeats the body for each word, i.e., with this markup:
<%@ taglib uri="http://custom.tag.com/demo" prefix...
output:
<html>
<body>
<p>Hello Tigger!</p>
<p>H...
With Maven, this is the directory structure:
./src
./src/main
./src/main/resources
./s...
There are three files to write:
pom.xml :
<project xmlns="http://maven.apache.org/POM/4.0.0"...
src/main/java/tagdemo/IterateTag.java :
package tagdemo;
import java.io.IOException...
src/main/resources/META-INF/demotag.tld :
<?xml version="1.0" encoding="UTF-8"?>
<!DO...
Build with:
mvn clean install
To use it as a dependency in other Maven projects:
<dependency>
<groupId>tag-demo</groupId>
...
Created by Fang on December 01, 2011 18:54:54
Last update: December 01, 2011 18:54:54
Use the varStatus attribute with the ui:repeat tag to get the iteration index:
<ui:repeat varStatus="status" var="item" value="#{...
The varStatus attribute specifies the name of the exported request scoped variable for the status of the iteration.The object is a POJO with the following read-only JavaBeans properties. This scoped variable has nested visibility.
begin of type Integer
end of type Integer
index of type int
step of type Integer
even of type boolean
odd of type boolean
first of type boolean
last of type boolean
Created by Fang on November 22, 2011 10:40:16
Last update: November 22, 2011 10:40:16
This is an example that uses tag handler, UI component and renderer together to support a custom taglib. The main purpose is to show how these components play together.
The tag renders
<ui:param name="extra" value="el interpreted"/>
...
as
<h3>my:foreach</h3>
<ul class="css class" extra...
These are the files:
The tag handler ( src/main/java/com/example/ForeachTagHandler.java ):
package com.example;
import java.util.Map;
...
The UI component ( src/main/java/com/example/UIForeach.java ):
package com.example;
import java.io.IOExcep...
The renderer ( src/main/java/com/example/ForeachRenderer.java ):
package com.example;
import java.io.IOExcep...
Faces config ( src/main/resources/META-INF/faces-config.xml ):
<?xml version="1.0" encoding="UTF-8"?>
<faces-c...
Taglib config ( src/main/resources/META-INF/foreach.taglib.xml ):
<?xml version="1.0" encoding="UTF-8"?>
<facelet...
