PHP

Warning: session_start()的解决方法

修改php.ini中的session.auto_start = 0 为 session.auto_start = 1

字符串运算符.
<?php
$a=my;
$b=name;
echo ($a.$b);    #把字符串$a与字符串$b连起来
?>

数组运算符+
+ 运算符把右边的数组附加到左边的数组后面，但是重复的键值不会被覆盖。
<?php
$a = array("a" => "apple", "b" => "banana");
$b = array("a" => "pear", "b" => "strawberry", "c" => "cherry");

$c = $a + $b; // Union of $a and $b
echo "Union of \$a and \$b: \n";
var_dump($c);

$c = $b + $a; // Union of $b and $a
echo "Union of \$b and \$a: \n";
var_dump($c);
?>

因为PHP需要定制，所以yum安装个人认为比较麻烦，所以跟据自己使用需要用源码包安装

从http://www.php.net下载PHP PHP4还是PHP5根据软件需要下载

以下使用PHP 5.2.5 Released安装
tar -jxvf php-5.2.5.tar.bz2
cd php-5.2.5

./configure --with-apxs2=/usr/local/apache2/bin/apxs \
--enable-mbstring --with-zlib --with-gd \
--with-jpeg-dir=/usr/local/lib --with-png-dir \
--with-mysql --with-mcrypt  --with-xsl --with-gettext\
--with-mysql-sock --with-ldap --with-mhash \
--with-imap --with-kerberos --with-imap-ssl

安装时所需支持依赖包，可以通过yum安装

make && make install
cp php.ini-dist /usr/local/lib/php.ini
安装后可以通过下面的代码测试PHP显示的相关信息
<?php phpinfo(); ?>

支持Mysql Postgres数据库

./configure --with-apxs2=/usr/local/apache2/bin/apxs --enable-mbstring --with-zlib --with-gd --with-jpeg-dir --with-png-dir --with-mysql=/usr/local/mysql --with-pgsql

This site has the repositories that will upgrade your PHP 5.1 to 5.2
 
nano -w /etc/yum.repos.d/utterramblings.repo
... and then paste the following into the editor:
[utterramblings]
name=Jason's Utter Ramblings Repo
baseurl=http://www.jasonlitka.com/media/EL$releasever/$basearch/
enabled=1
gpgcheck=1
gpgkey=http://www.jasonlitka.com/media/RPM-GPG-KEY-jlitka
NOTE: If the above URL returns a 404 then try hard-coding $releasever to your EL version ('EL4' or 'EL5') and the $basearch to whatever is appropriate ('i386' or 'x86_64').
 
For those new to linux, the nano command is for a linux editor, and once you type the 6 lines, press ctrl O to write the file and press enter to save to the file name given.
 
Once you've taken care of the above, you'll be able to easily upgrade with a simple 'up2date -u' or 'yum update'.
 
If you get dependency errors, if you do 'yum update', you might want to try just the php update by trying 'yum - y php update'.
 
Updating:
 php                     x86_64     5.2.6-jason.1    utterramblings    3.9 M
 php-cli                 x86_64     5.2.6-jason.1    utterramblings    2.7 M
 php-common              x86_64     5.2.6-jason.1    utterramblings    494 k
Updating for dependencies:
 php-devel               x86_64     5.2.6-jason.1    utterramblings    568 k
 php-gd                  x86_64     5.2.6-jason.1    utterramblings    342 k
 php-imap                x86_64     5.2.6-jason.1    utterramblings    112 k
 php-ldap                x86_64     5.2.6-jason.1    utterramblings     61 k
 php-mbstring            x86_64     5.2.6-jason.1    utterramblings    1.3 M
 php-mysql               x86_64     5.2.6-jason.1    utterramblings    275 k
 php-odbc                x86_64     5.2.6-jason.1    utterramblings    120 k
 php-pdo                 x86_64     5.2.6-jason.1    utterramblings    166 k
 php-xml                 x86_64     5.2.6-jason.1    utterramblings    336 k
 php-xmlrpc              x86_64     5.2.6-jason.1    utterramblings    135 k
 
after the initial php and its dependencies are updated you can update the rest.
 
#yum –y update –gets errors to install the list below…so just yum install each separately.
eg: #yum -y apr apr-util update
 
Updating:
 apr                     x86_64     1.2.12-2.jason.1  utterramblings    266 k
 apr-util                x86_64     1.2.12-5.jason.1  utterramblings    166 k
 ed                      x86_64     0.2-39.el5_2     updates            49 k
 httpd                   x86_64     2.2.8-jason.3    utterramblings    2.6 M
 mod_perl                x86_64     2.0.3-14.jason.1  utterramblings    5.5 M
 mysql                   x86_64     5.0.58-jason.2   utterramblings    6.5 M
 mysql-devel             x86_64     5.0.58-jason.2   utterramblings    2.9 M
 mysql-server            x86_64     5.0.58-jason.2   utterramblings     11 M
 pcre                    x86_64     7.6-jason.1      utterramblings    592 k
 php-pear                noarch     1:1.6.2-1.jason.1  utterramblings    418 k