Learn how to use the file test operators.
- [Voiceover] Perl provides a large number of…file test operators.…These are used for testing the status of…an object in the file system, like a file.…For example, here I'm using the -e operator…to see if a file exists.…Down here on line nine,…you see there's an if statement and…in the if statement I have -e and a file name.…So -e is the file test operator that tests if a file exists.…The file test operator takes one argument:…it can be a file name, a file handle, or a directory handle.…
We'll cover handles when we cover file IO…later on in the course,…but if I go ahead and run this, without opening the file…or anything like that, it just checks the file system…to see if the file exists.…If it does, it returns true, as in this case it does.…If I change this file name to a file name that doesn't exist…and I go ahead and I run that, you'll notice my result is…No such file or directory.…That's the error given in the special error variable,…$!…If the file test returns false, it checks to see with…the else, it checks to see if there is an error message.…
Watch to learn the details of the Perl syntax, from variables, conditionals, loops, and data structures to regular expressions, functions, and references. A quick-start guide is included for experienced developers who want to get up and running with Perl 5 fast, and the entire course is recommended for both new and experienced programmers alike. Later chapters cover file handling and reusing code with Perl modules, plus Perl best coding practices.
- Understanding Perl's general syntax and the anatomy of a Perl script
- Writing statements and expressions
- Creating assignments
- Working with variables and strings
- Using data types effectively
- Defining logical flow with conditionals and loops
- Using special variables
- Using Perl operators
- Performing simple Perl programming tasks with expressions
- Matching data
- Defining and calling functions
- Using references
- Handling files in the file I/O
- Using built-in functions
- Reusing code with modules
- Coding with Perl best practices
Skill Level Intermediate
1. Setting Up
About Perl3m 36s
2. Quick Start
3. Basic Syntax
4. Values and Variables
7. Special Variables
9. Regular Expressions
11. References and Structures
12. File I/O
13. Built-In Functions
15. Best Practices
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