execute commands in sub-processes

 The Symfony Process Component helps with executing commands in
 sub-processes by providing easy access to standard and error output
 in real-time. It is especially handy for dealing with long running
 sub-processes due to its feature to run them asynchronously, while
 still providing access to their full and incremental output. It
 additionally supports signals, provides the PID of a sub-process
 and allows the definition of process timeouts.
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 Symfony is a PHP framework, a set of tools and a development methodology.