CODEWITHSUNDEEP
rubyfileioerrno
Civatrix
Civatrix

Reputation: 2616

How to create a file in Ruby

I'm trying to create a new file and things don't seem to be working as I expect them to. Here's what I've tried:

File.new "out.txt"
File.open "out.txt"
File.new "out.txt","w"
File.open "out.txt","w"

According to everything I've read online all of those should work but every single one of them gives me this:

ERRNO::ENOENT: No such file or directory - out.txt

This happens from IRB as well as a Ruby script. What am I missing?

Upvotes: 211

Views: 275010

Answers (10)

Melanie Shebel
Melanie Shebel

Reputation: 2914

There are several different options you could try. (This is not meant to be an exhaustive list... just tiring.)

File.new

file_name = File.new("out.txt", "w")
file_name.close

File.open

File.open("out.txt", "w") do |file|
  #other stuff here
end

File.write

File.write('out.txt', 'contents here')

FileUtils.touch

require 'fileutils'
FileUtils.touch('out.txt')

IO.sysopen and IO.sysnew

fd = IO.sysopen("out.txt", "w")
file = IO.new(fd, "w")
file.puts "other stuff"
file.close

Tempfile

require 'tempfile'
tempfile = Tempfile.new('out')
tempfile.puts "some text"
tempfile.close

Pathname and open

require 'pathname'
path = Pathname.new("out.txt")
path.open("w") do |file|
  file.puts "some text"
end

Chart source: How to write to a file in Ruby (Disclosure: I wrote it)

Various methods for file creation in Ruby

Upvotes: 1

zanbri
zanbri

Reputation: 6006

Use:

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

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

... but that has the risk of forgetting to call close (such as if an exception is raised, or you return early).

Upvotes: 486

ispirett
ispirett

Reputation: 666

data = 'data you want inside the file'.

You can use File.write('name of file here', data)

Upvotes: 3

Chris Bunch
Chris Bunch

Reputation: 89793

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

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

Upvotes: 33

Nicola Mingotti
Nicola Mingotti

Reputation: 998

If the objective is just to create a file, the most direct way I see is:

 FileUtils.touch "foobar.txt"

Upvotes: 18

the Tin Man
the Tin Man

Reputation: 160553

File.new and File.open default to read mode ('r') as a safety mechanism, to avoid possibly overwriting a file. We have to explicitly tell Ruby to use write mode ('w' is the most common way) if we're going to output to the file.

If the text to be output is a string, rather than write:

File.open('foo.txt', 'w') { |fo| fo.puts "bar" }

or worse:

fo = File.open('foo.txt', 'w')
fo.puts "bar"
fo.close

Use the more succinct write:

File.write('foo.txt', 'bar')

write has modes allowed so we can use 'w', 'a', 'r+' if necessary.

open with a block is useful if you have to compute the output in an iterative loop and want to leave the file open as you do so. write is useful if you are going to output the content in one blast then close the file.

See the documentation for more information.

Upvotes: 14

GMD
GMD

Reputation: 708

Try 

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

without using the

File.new "out.txt"

Upvotes: 42

Nicholas Terry
Nicholas Terry

Reputation: 1920

The directory doesn't exist. Make sure it exists as open won't create those dirs for you.

I ran into this myself a while back.

Upvotes: 10

Alex Tamoykin
Alex Tamoykin

Reputation: 185

You can also use constants instead of strings to specify the mode you want. The benefit is if you make a typo in a constant name, your program will raise an runtime exception.

The constants are File::RDONLY or File::WRONLY or File::CREAT. You can also combine them if you like.

Full description of file open modes on ruby-doc.org

Upvotes: 0

tom
tom

Reputation: 2365

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.

Upvotes: 21

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