Pipex It must take 4 arguments: • file1 and file2 are file names. • cmd1 and cmd2 are shell commands with their parameters. How does it work? in Linux: $make $./pipex infile "ls -l" "wc -l" outfile or $> ./pipex infile "grep a1" "wc -w" outfile prototype：< file1 cmd1 | cmd2 > file2
