There is a ruby function that checks if a file exists. This function returns true if the file exists.

Why? If you try to open a file that doesn’t exist, at best it will return an empty string and at worst it will crash your program. That would lead to unexpected results and thus you want to check if the file exists.

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File exists in ruby

Example

The following ruby code will check if the specified file exists or not.

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#!/usr/bin/ruby

#Ruby function to check if file existensts
if(File.exist?('example.txt'))
puts 'File exists'
else
puts 'File does not exist'
end

If no file root is specified, it will look for the file in the same directory as the code.
If the file exists, it will return true. If not, it will return false.

Error checking

Sometimes you want to check if a file exists before continuing the program. This leads to clean code: first check for errors, if no errors continue.

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#!/usr/bin/ruby

#Ruby function to check if file existensts
if(!File.exist?('example.txt'))
puts 'File does not exist'
end

puts 'Ruby'

Exercises

  1. Check if a file exists on your local disk
  2. Can you check if a file exists on an external disk?