PHP JSON extension not avaliable

yes-no

　　According to php.net, “there is no installation needed to use [json_encode() and json_decode()]; they are part of the PHP Core“. While it’s certainly true that they are part of the source code, many of the binary packages available for RPM-based platforms (like Red Hat, CentOS and Fedora) have them disabled by default.
　　There are a number of extensions (PEAR and otherwise) available as RPMs in the official repositories, but sadly not php-json. To enable these functions on CentOS (and by nature, RHEL) 5, the process is simple but not immediately obvious:

• Make sure you have php, pear and the necessary development packages installed: $ sudo yum install php php-pear php-devel $ sudo yum install gcc make
  
• Use PECL to download the json package: $ sudo pecl download json
  
• Owing to some odd default memory settings we can’t download and install the package with PECL, we have to use PEAR: $ sudo pear install json-1.2.1.tgz 　　PEAR will then trundle through and handle the configure, make and make install commands for you
  
  
• Create a new file in /etc/php.d called json.ini, containing the following: ; php-json package - http://pecl.php.net/package/json extension=json.so
  
• Reload apache: $ sudo service httpd>
  
• Test your work: $ php -r 'var_dump(function_exists("json_encode"));' 　　All being well, that’ll return bool(true)
  
  

　　…and there you have it.
　　Note: There’s a chance you’ll run in to an error that looks like this:
/bin/sh: bad interpreter: Permission denied Cannot find autoconf. Please check your autoconf installation and the $PHP_AUTOCONF environment variable is set correctly and then rerun this script. 　　… most likely, this is because your temporary partition is mounted with ‘noexec’, check the output of mount and look for the line that refers to /tmp to confirm the presence of ‘noexec’ in the mount options. In this instance you’ll either have to re-mount /tmp without noexec (by removing it from /etc/fstab) or untar, phpize, configure, make and make install manually.