the requested PHP extension curl is missing from your system

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Updating dependencies (including require-dev)
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  Problem 1
    - guzzle/guzzle v3.9.3 requires ext-curl * -> the requested PHP extension curl is missing from your system.
    - guzzle/guzzle v3.9.2 requires ext-curl * -> the requested PHP extension curl is missing from your system.
    - guzzle/guzzle v3.9.1 requires ext-curl * -> the requested PHP extension curl is missing from your system.
    - guzzle/guzzle v3.9.0 requires ext-curl * -> the requested PHP extension curl is missing from your system.
    - guzzle/guzzle v3.8.1 requires ext-curl * -> the requested PHP extension curl is missing from your system.
    - guzzle/guzzle v3.8.0 requires ext-curl * -> the requested PHP extension curl is missing from your system.
    - guzzle/guzzle v3.7.4 requires ext-curl * -> the requested PHP extension curl is missing from your system.
    - guzzle/guzzle v3.7.3 requires ext-curl * -> the requested PHP extension curl is missing from your system.
    - guzzle/guzzle v3.7.2 requires ext-curl * -> the requested PHP extension curl is missing from your system.
    - guzzle/guzzle v3.7.1 requires ext-curl * -> the requested PHP extension curl is missing from your system.
    - guzzle/guzzle v3.7.0 requires ext-curl * -> the requested PHP extension curl is missing from your system.
    - guzzle/guzzle 3.9.x-dev requires ext-curl * -> the requested PHP extension curl is missing from your system.
    - Installation request for guzzle/guzzle ~3.7 -> satisfiable by guzzle/guzzle[3.9.x-dev, v3.7.0, v3.7.1, v3.7.2, v3.7.3, v3.7.4, v3.8.0, v3.8.1, v3.9.0, v3.9.1, v3.9.2, v3.9.3].

  To enable extensions, verify that they are enabled in your .ini files:
    - /etc/php5/cli/php.ini
    - /etc/php5/cli/conf.d/05-opcache.ini
    - /etc/php5/cli/conf.d/10-pdo.ini
    - /etc/php5/cli/conf.d/20-json.ini
    - /etc/php5/cli/conf.d/20-readline.ini
  You can also run `php --ini` inside terminal to see which files are used by PHP in CLI mode.

sudo apt-get install php5-curl