The program must be executed as follows:
./pipex file1 cmd1 cmd2 file2

And behave like the shell command:
$> < file1 cmd1 | cmd2 > file2

It must take 4 arguments:
• file1 and file2 are file names.
• cmd1 and cmd2 are shell commands with their parameters.

• Handle REDIRECTION
• Handle PIPES
• Handle files
• Output Error on STDERR
• Output the right output status (echo $?)
• Handle right orders as the sh handles the order list of commands and files to read (bonus of bonus, a preparation for the Minishell, the tip to handle correctly this is that bash handles each command asynchronously depending if the command needs STDIN or not. Ex: ls is a command that do not need an input, but cat may need)

Examples

$> ./pipex infile "ls -l" "wc -l" outfile ------------------------- OK
Should behave like: < infile ls -l | wc -l > outfile
$> ./pipex infile "grep a1" "wc -w" outfile ------------------ OK
Should behave like: < infile grep a1 | wc -w > outfile
$> ./pipex infile "cat -e" "tr ' ' '_'" outfile
Should behave like: < infile cat -e | tr ' ' '_' > outfile

• Validate Arguments