Book Image

Julia 1.0 Programming - Second Edition

By : Ivo Balbaert
Book Image

Julia 1.0 Programming - Second Edition

By: Ivo Balbaert

Overview of this book

The release of Julia 1.0 is now ready to change the technical world by combining the high productivity and ease of use of Python and R with the lightning-fast speed of C++. Julia 1.0 programming gives you a head start in tackling your numerical and data problems. You will begin by learning how to set up a running Julia platform, before exploring its various built-in types. With the help of practical examples, this book walks you through two important collection types: arrays and matrices. In addition to this, you will be taken through how type conversions and promotions work. In the course of the book, you will be introduced to the homo-iconicity and metaprogramming concepts in Julia. You will understand how Julia provides different ways to interact with an operating system, as well as other languages, and then you'll discover what macros are. Once you have grasped the basics, you’ll study what makes Julia suitable for numerical and scientific computing, and learn about the features provided by Julia. By the end of this book, you will also have learned how to run external programs. This book covers all you need to know about Julia in order to leverage its high speed and efficiency for your applications.
Table of Contents (17 chapters)
Title Page
Copyright and Credits
Packt Upsell

Running shell commands

To interact with the operating system from within the Julia REPL, there are a few helper functions available, as follows:

  • pwd(): this function prints the current directory, for example, "d:\\test"
  • cd("d:\\test\\week1"): this function helps to navigate to subdirectories
  • ;: in the interactive shell, you can also use shell mode using the ; modifier, for example: ; cd folder: navigates to folder

However, what if you want to run a shell command by using the operating system (the OS)? Julia offers efficient shell integration through the run function, which takes an object of type Cmd, defined by enclosing a command string in backticks (``).



The following are some examples for Linux or macOS X (at the time of writing: September 2018):

# Code in Chapter 9\shell.jl: 
cmd = `echo Julia is smart` 
   typeof(cmd) #> Cmd  
   run(cmd) # returns Julia is smart
   run(`date`) #> Sat Jul 14 09:44:50 GMT 2018 
   cmd = `cat file1.txt` 
   run(cmd) # prints the contents of file1.txt...