Invoking an external command in Python is a two step process:

from subprocess import call
call(["ls","-1"])

The earning potential of a software developer largely depends on their knowledge, their chosen area of expertise, experience and flexibility to relocate if necessary.  In the ever changing landscape of Information Technology, many argue that the way to make more money is to specialize in a technology that fewer people are using.  As an example, there are tons of Java programmers out there, but nowhere near enough in lesser known languages such as Perl or Python.  However, there are plenty of opportunities for folks who are willing to burn the midnight oil to gain skills in these niche disciplines.

Because the Information Technology Industry is a rapidly evolving entity, gunning for the "Next Big Thing" is constantly an arm’s length away.  For this reason, developers looking to get requisite knowledge to successfully compete can, for the most part, expect to resign their weekends for the LOVE of code and studying.   And, it’s fair to say that a stick-to-itiveness to teach yourself how to code can be more important than any degree when job prospecting.  Sam Nichols, a mobile developer at SmugMug, puts it this way: “Build a table, build a computer, build a water gun, build a beer bong, build things that will take a week and build things that need to be done in 40 minutes before the party. Making stuff is what this field is all about and getting experience building things, especially with others, especially when it breaks and fails along the way can help with perspective and resiliency.”

Software developers already skilled at writing code are readily able to translate that knowledge to web development. The fact that the information technology sector has shifted largely to web-based infrastructure and software application as system (SaaS) database and operating system capabilities, means that software developers have a wide variety of opportunity in the web development segment of the consulting and job market.

If you are a software developer seeking to increase your earning potential, gaining expertise in  Web development  enhances your ability to attract new opportunities. The more creative a software developer, the far better chance they will have at benefitting from current market demand for new technologies and software innovation. Customization is hot right now, and software developers involved in the creation of updates and unique features to SaaS can add extra value to their portfolio with very little time and effort involved.

 In order for software developers to stay abreast of their field, continuing education and is required to ensure that technical skills are up-to-date. Gaining knowledge in design of computer applications is one of the main objectives in the development and planning of software products.
Once adequate knowledge has been acquired, many software developers can use those insights to develop custom software for a client as a consultant.

Memory management is always a priority in pretty much any programming language you would want to use. In the lower level languages such as C, there are a number of functions which help you manage the memory your application uses, but they are not the easiest to use. Some of the more modern programming languages such as Python, Ruby, Perl, and of course the subject of this article, Javascript all have a built in feature called garbage collection.

Garbage collection essentially means that the languages compiler will automatically free the memory being occupied by unused variables and objects, but there is no telling when this could occur. It is purely down to the compiler to decide when the garbage collection process should be initiated.