arguments

Ruby command line arguments

Ruby FAQ: How do I read command line arguments in a Ruby script (Ruby command line args)?

To read command line args in a Ruby script, use the special Ruby array ARGV to get the information you need. Here are a few examples.

1) Getting the number of command line args

To get the number of command line arguments passed in to your Ruby script, check ARGV.length, like this:

By Alvin Alexander on November 19, 2011

Scala functions - named arguments and default arguments

A nice feature of Scala is that in addition to letting you call and define functions just like you do in Java, you can also use both named arguments and default arguments. In this brief tutorial we'll look at both of these language features.

With Scala's named arguments (parameters), you can specify the names of function or method arguments when calling the method. Here's an example:

By Alvin Alexander on November 1, 2012

How to read shell script command line arguments

Unix/Linux shell script args FAQ: How do I access Unix or Linux shell script command line arguments?

If you're just expecting one or two parameters to be passed into a Unix or Linux shell script, and these parameters aren't options/flags to your script (like "-a" or "-f"), you can access the shell script arguments through variables named $1, $2, etc.

Here's a short example where I'm expecting two shell script command line arguments. If either of these command line arguments is blank, I display a usage statement and exit my script:

By Alvin Alexander on May 3, 2013

How to read Perl command-line arguments

Perl FAQ: How do I read command-line arguments in Perl?

If you want to handle simple Perl command line arguments, such as filenames and strings, this tutorial is for you. If you want to handle command-line options (flags) in your Perl scripts (like "-h" or "--help"), this new Perl getopts command line options/flags tutorial is what you need.

By Alvin Alexander on March 1, 2013

Java sound - A command line Java program to play a sound file (in headless mode)

As part of my ongoing HAL 9000 voice obsession, I downloaded a bunch of "HAL 9000" sound files last night. But, when you double-click a sound file on Mac OS X, it automatically plays through iTunes, which is good for some things, but bad for what I wanted to do. So, I wrote a quick little "Java sound" program to read the name of a sound file from the command line, and then play the sound file.

By Alvin Alexander on October 17, 2012

Bash shell script - how to prompt and read user input

Unix/Linux bash shell script FAQ: How do I prompt a user for input from a shell script (Bash shell script), and then read the input the user provides?

Answer: I usually use the shell script "read" function to read input from a shell script. Here are two slightly different versions of the same shell script. This first version prompts the user for input only once, and then dies if the user doesn't give a correst Y/N answer:

By Alvin Alexander on August 31, 2011

PHP args - How to read command line arguments in PHP

PHP command line args FAQ: How do I read command line arguments in PHP?

Answer: You just need to access the PHP argv array, as shown in this example:

By Alvin Alexander on September 5, 2010

How to access arguments to a Perl subroutine or function

Perl question: How do I access the arguments that have been passed to my subroutine or function?

Answer: The special array @_ holds the values that are passed into a subroutine/function, and you use that array to access those arguments. The first argument is represented by the variable $_[0], the second argument is represented by $_[1], and so on.

It may also help to know that number of elements passed in to your subroutine is given by the value of scalar(@_).

By Alvin Alexander on August 8, 2011
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