If you want the text to mean anything, you're going to have to parse it. The Ruby options are terminated by the first word on the command line that doesn't start with a hyphen, or by the special flag ``--'' (two hyphens). Parsing command-line arguments. For example, ARGV[0] returns the first argument passed to the Ruby script. Programming languages C C uses argv to process command-line arguments. Different command-line argument parsing methods are used by different programming languages to parse command-line arguments. Parses command line arguments argv in order when environment variable POSIXLY_CORRECT is set, and in permutation mode otherwise. It looks something like this: Defining the options Start by requiring optparse, and initializing a new OptionParser object with a block that defines which options the parser accepts. When a block is given, each non-option argument is yielded. Parses command line arguments argv in order. The first phase is turning any command-line arguments into a data structure that I can easily consult during the actual program. When optional into keyword argument is provided, the parsed option values are stored there via []= method (so it can be Hash, or OpenStruct, or other similar object). Learn how to parse command line options in your Ruby scripts with the OptionParser class, available in the Ruby standard library. Passing in arguments via the command line is an extremely basic programming task, and a necessity for anyone trying to write a simple Command-Line Interface (CLI). Let's do a quick overview of the process! The usual way So here I am, maintaining the command line arguments, which in turn, will be variables, in four different places. Clint is an alternative Ruby command line argument parser that's very good for programs using the subcommand pattern familiar from git(1), svn(1), apt-get(8), and many others. Command-line arguments are just text. Also, the time argument is nil if no argument is provided to the--time option. # File lib/optparse.rb, line 1441 def parse ( * argv ) argv = argv [ 0 ]. Every time I need to write a Bash script which accepts command line arguments, I go back to this great answer in StackOverflow - How do I parse command line arguments in Bash. For dirt-simple argument parsing… Fortunately, there are several good libraries that can help you with the parsing. Returns the … In addition, it separates option declarations from usage and help messages becuase the author feels like that's a better idea. Over the years, a somewhat standard syntax for command-line arguments has emerged. Here, Ill use OptionParser to write cat2.rb, a second Ruby version of cat that supports a few of the real cats command-line arguments. 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