无法安装composer - 缺少json扩展名

Question

I'm trying to install composer on my Ubuntu 13.10 machine but the following error occurs:

Some settings on your machine make Composer unable to work properly.
Make sure that you fix the issues listed below and run this script again:

The json extension is missing.
Install it or recompile php without --disable-json

php --version gives me PHP 5.5.3-1ubuntu2 (cli) so I think it should have the json extension installed.

Answer 1

just install the module:

sudo apt-get install php5-json

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EDIT - Reason:

See Heanzo Beanzo Comment:

It has been removed in recent packages due to a license conflict see bug on php.net .