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How to create a file in Ruby

Tags:

file

io

ruby

errno

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What is file in Ruby?

A File is an abstraction of any file object accessible by the program and is closely associated with class IO . File includes the methods of module FileTest as class methods, allowing you to write (for example) File. exist?("foo") .


Use:

File.open("out.txt", [your-option-string]) {|f| f.write("write your stuff here") }

where your options are:

  • r - Read only. The file must exist.
  • w - Create an empty file for writing.
  • a - Append to a file.The file is created if it does not exist.
  • r+ - Open a file for update both reading and writing. The file must exist.
  • w+ - Create an empty file for both reading and writing.
  • a+ - Open a file for reading and appending. The file is created if it does not exist.

In your case, 'w' is preferable.

OR you could have:

out_file = File.new("out.txt", "w")
#...
out_file.puts("write your stuff here")
#...
out_file.close

Try

File.open("out.txt", "w") do |f|     
  f.write(data_you_want_to_write)   
end

without using the

File.new "out.txt"

Try using "w+" as the write mode instead of just "w":

File.open("out.txt", "w+") { |file| file.write("boo!") }

OK, now I feel stupid. The first two definitely do not work but the second two do. Not sure how I convinced my self that I had tried them. Sorry for wasting everyone's time.

In case this helps anyone else, this can occur when you are trying to make a new file in a directory that does not exist.