This project about understanding multiprocessing.
Program executed as follows:

./pipex file1 cmd1 cmd2 ... cmdN file2

where cmd are shell command with their parameters.

It behave the same as the shell command:

$> < file1 cmd1 | cmd2 | ... | cmdN > file2

Program supports << and >> when the first parameter is "hede_doc".

This:

$> ./pipex here_doc LIMITER cmd cmd1 file

behaves like this:

$> cmd << LIMITER | cmd1 >> file

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